Abstract
The diacetate complexes trans-[Ru(κ1-OAc)2(PPh3)2(NN)] (NN = ethylenediamine (en) (1), 2-(aminomethyl)pyridine (ampy) (2), 2-(aminomethyl)pyrimidine (ampyrim) (3)) have been isolated in 76–88% yield by reaction of [Ru(κ2-OAc)2(PPh3)2] with the corresponding nitrogen ligands. The ampy-type derivatives 2 and 3 undergo isomerization to the thermodynamically most stable cationic complexes [Ru(κ1-OAc)(PPh3)2(NN)]OAc (2a and 3a) and cis-[Ru(κ1-OAc)2(PPh3)2(NN)] (2b and 3b) in methanol at RT. The trans-[Ru(κ1-OAc)2(P2)2] (P2 = dppm (4), dppe (5)) compounds have been synthesized from [Ru(κ2-OAc)2(PPh3)2] by reaction with the suitable diphosphine in toluene at 95 °C. The complex cis-[Ru(κ1-OAc)2(dppm)(ampy)](6) has been obtained from [Ru(κ2-OAc)2(PPh3)2] and dppm in toluene at reflux and reaction with ampy. The derivatives trans-[Ru(κ1-OAc)2P2(NN)] (7–16; NN = en, ampy, ampyrim, 8-aminoquinoline; P2 = dppp, dppb, dppf, (R)-BINAP) can be easily synthesized from [Ru(κ2-OAc)2(PPh3)2] with a diphosphine and treatment with the NN ligands at RT. Alternatively these compounds have been prepared from trans-[Ru(OAc)2(PPh3)2(NN)] by reaction with the diphosphine in MEK at 50 °C. The use of (R)-BINAP affords trans-[Ru(κ1-OAc)2((R)-BINAP)(NN)] (NN = ampy (11), ampyrim (15)) isolated as single stereoisomers. Treatment of the ampy-type complexes 8–15 with methanol at RT leads to isomerization to the cationic derivatives [Ru(κ2-OAc)P2(NN)]OAc (8a–15a; NN = ampy, ampyrim; P2 = dppp, dppb, dppf, (R)-BINAP). Similarly to 2, the dipivalate trans-[Ru(κ1-OPiv)2(PPh3)2(ampy)] (18) is prepared from [Ru(κ2-OPiv)2(PPh3)2] (17) and ampy in CHCl3. The pincer acetate [Ru(κ1-OAc)(CNNOMe)(PPh3)2] (19) has been synthesized from [Ru(κ2-OAc)2(PPh3)2] and HCNNOMe ligand in 2-propanol with NEt3 at reflux. In addition, the dppb pincer complexes [Ru(κ1-OAc)(CNN)(dppb)] (CNN = AMTP (20), AMBQPh (21)) have been obtained from [Ru(κ2-OAc)2(PPh3)2], dppb, and HAMTP or HAMBQPh with NEt3, respectively. The acetate NN and pincer complexes are active in transfer hydrogenation with 2-propanol and hydrogenation with H2 of carbonyl compounds at S/C values of up to 10000 and with TOF values of up to 160000 h–1.
Introduction
The ever-increasing need to produce valuable organic compounds by industry requires the development of new and more efficient homogeneous transition-metal catalysts. Selective transformations can be achieved through an appropriate choice of ligands at the metal, leading to well-designed catalysts characterized by high productivity. Polydentate nitrogen and phosphine ligands have been extensively employed with the aim to obtain robust and catalytically active species. More recently, the use of carboxylates as ancillary ligands has been demonstrated to be particularly promising in many catalytic processes, since carboxylate may play a non-innocent role, acting as a proton acceptor for H–H and C–H splitting reactions1 and stabilizing monomeric species on account of the facile switching capability from a mono- to a bidentate mode of coordination. Furthermore, carboxylates are labile ligands that can dissociate easily, allowing a free site for substrate coordination and formation of the catalytically active species. With regard to ruthenium, which has been widely employed in homogeneous catalysis for its high performance and versatility,2 it is worth mentioning that ruthenium carboxylates have been shown to catalyze the hydrogenation (HY) of olefins3 and carbonyl compounds.4 These types of complexes can also promote alcohol dehydrogenation5 and the cycloisomerization of alkynols to five- to seven-membered endocyclic enol ethers.6 Ruthenium carboxylate catalysts have been found to activate C–H bonds,7 promote functionalization reactions,8 efficiently direct C–H/C–O bond arylations with phenols in water,9 and react with aldehydes.10 Ruthenium phosphine carboxylate complexes have been reported to catalyze the hydrogenation of carboxylic acids and their derivatives to alcohols,11 while the employment of BINAP-Ru(II) dicarboxylates12 afforded the asymmetric hydrogenation of unsaturated carboxylic acids to the corresponding saturated products.13 Furthermore, [Ru(O2CR)2(CO)2(PPh3)2] (R = CH2OCH3, iPr, tBu, 2-cC4H3O, Ph) were successfully applied as catalysts in the addition of carboxylic acids to propargylic alcohols to give the corresponding β-oxo esters used in the pharma industry.14 Among organic transformations entailing ruthenium catalysts, the reduction of carbonyl compounds via HY15 and transfer hydrogenation (TH)16 are environmentally benign methods and core processes accepted by the industry for the synthesis of alcohols. Several highly efficient ruthenium catalysts have been developed for both TH and HY, namely [RuCl(η6-arene)(TsDPEN)]12,17 and trans-[RuCl2P2(diamine)] (P2 = diphosphine) complexes, which represent a milestone for these types of catalytic processes.18 The employment of the ampy12 ligand in place of diamines has resulted in the isolation of cis-[RuCl2P2(ampy)] derivatives that show high catalytic activity for enantioselective TH and HY.19 In addition, the related pincer CNN complexes [RuCl(CNN)P2], containing functionalized ampy ligands, have proved to be exceptionally productive catalysts for TH and HY, including those of biomass-derived carbonyl compounds.20 The replacement of the chloride in trans-[RuCl2P2(diamine)] with sterically hindered carboxylates as anionic ligands has resulted in the highly efficient catalysts [Ru(OCOR)2P2(en)]12 (P2 = dppe, xantphos;12 R = tBu, Ph, 1-adamantyl) for the selective HY of aldehydes under base-free or acidic conditions.21
During our studies aiming to expand the use of ruthenium carboxylates in catalysis, we have found that the cationic monocarbonyl derivatives [RuX(CO)P2(NN)]X22 (X = Cl, OAc; NN = en, ampy: P2 = dppb, dppf),12 the trifluoroacetate [Ru(OCOCF3)2(dppb)(XCH2CH2X)]23 (X = NH2, OH) derivatives, and the mixed acetate acetylacetonate complex [Ru(OAc)(acac)(dppb)(ampy)]24 have been proven to be highly active catalysts in the TH and HY reductions. The pincer CNN ruthenium acetate complex [Ru(OAc)(AMTP)(dppb)]12 has shown the highest activity in TH with a TOF value ot up to 3.8 × 106 h–1, consistent with the easier substitution of the carboxylate vs Cl in protic media.25 Acetate ruthenium compounds in combination with carbene ligands, namely [RuBr(OAc)(PPh3)(P-aNHC)] and [Ru(OAc)(P-aNHC)2]Br (P-aNHC = phosphine-abnormal-NHC ligands), have displayed high rates and productivities in TH and in fast Oppenauer-type oxidation reactions (TOFs of up to 600000 h–1).26 With regard to other applications, ruthenium carboxylate complexes have been described as efficient photosensitizers for TiO2 semiconductor solar cells.27 New anticancer agents have been prepared by employing ruthenium carboxylate complexes with the aim of obtaining compounds with good solubility in the culture medium.28 We have recently reported the synthesis of a new class of cationic carboxylate ruthenium complexes, [Ru(κ1-OCOR)(CO)(dppb)(phen)](OCOR)12 (R = Me, tBu), that display high cytotoxic activity against anaplastic thyroid cancer cell lines, with EC50 values much lower than that of cisplatin, leading to an increment of apoptosis and decrease in cancer cell aggressiveness.29
This paper discloses a convenient procedure for the preparation of a series of neutral trans/cis and cationic carboxylate ruthenium complexes containing bidentate nitrogen and phosphine ligands through straightforward syntheses by starting from the [Ru(κ2-OCOR)2(PPh3)2] (R = Me, tBu) precursors. Pincer CNN acetate complexes have also been easily obtained through this synthetic route. The carboxylate ruthenium complexes show activity in TH and HY reactions, allowing the reduction of carbonyl compounds at S/C values of up to 10000 and TOF values of up to 160000 h–1.
Results and Discussion
Synthesis of Diacetate Ruthenium Complexes with PPh3 and NN Ligands
Treatment of [Ru(κ2-OAc)2(PPh3)2] with 1 equiv of en in methyl ethyl ketone (MEK) at room temperature for 45 min affords the complex trans,cis-[Ru(κ1-OAc)2(PPh3)2(en)] (1), isolated in 84% yield (Scheme 1).
Scheme 1. Synthesis of Diacetate Ruthenium Complexes with PPh3 and NN Ligands.
The 1H NMR spectrum of 1 in CDCl3 displays two broad singlets at δ 5.31 and 2.67 for the amino and the methylene groups of the en ligand, respectively, with a singlet at δ 1.67 for the methyl acetate. In a fashion similar to that for 1, the derivative trans,cis-[Ru(κ1-OAc)2(PPh3)2(ampy)] (2) is synthesized in high yield (85%) by the reaction of [Ru(κ2-OAc)2(PPh3)2] with ampy at room temperature in MEK or dichloromethane (Scheme 1 and methods 1 and 2 in the Experimental Section). Alternatively, 2 has been obtained in 76% yield through a one-pot reaction from [RuCl2(PPh3)3], NaOAc and ampy in acetone via the intermediate [Ru(κ2-OAc)2(PPh3)2] (method 3). The 31P{1H} NMR spectrum of 2 in CD2Cl2 exhibits two doublets at δ 44.6 and 39.4 with a 2J(P,P) value of 31.3 Hz, whereas the methylene protons of the ampy appear in the 1H NMR spectrum as a broad multiplet at δ 4.18 and the NH2 signal is at δ 6.70. This downfield chemical shift is consistent with the presence of a NH···O=C hydrogen-bond interaction of the NH2 protons with the two acetate ligands, in contrast with the related complexes trans-[Ru(κ1-OAc)2P2(ampy)] (P2 = DiPPF, DCyPF)12 containing a bulky diphosphine,30 in which only one NH interacts with an acetate group.31
Recently, we reported that trans-[Ru(κ1-OAc)2(DiPPF)2(NN)] derivatives, displaying the bulky diphosphine DiPPF, are quickly obtained from [Ru(κ2-OAc)2(DiPPF)] and NN (en, ampy) at low temperature.31 While the en complex is thermally stable, the ampy compound undergoes rapid isomerization at room temperature to the thermodynamically most stable cationic and cis complexes in methanol. Accordingly, dissolution of 2 in methanol at RT for 24 h afforded a mixture of the cationic cis-[Ru(κ2-OAc)(PPh3)2(ampy)]OAc (2a) and cis,cis-[Ru(κ1-OAc)2(PPh3)2(ampy)] (2b) in a 3:2 molar ratio (method 1), isolated in 85% yield (Scheme 1). Alternatively, the same mixture is formed from [Ru(κ1-OAc)2(PPh3)2] and ampy in methanol at RT and was isolated in 83% yield (method 2). Attempts to isomerize 2 to 2a,b in toluene at 100 °C failed, leading to decomposition with release of PPh3, as inferred from 31P{1H} NMR analysis. The 31P{1H} NMR spectrum of 2a,b in CD3OD displays two doublets at δ 60.2 and 47.1 (2J(P,P) = 32.6 Hz) for the cationic complex 2a and two doublets at δ 65.0 and 49.0 (2J(P,P) = 29.3 Hz) for the cis isomer 2b. The doublet at δH 7.98 (3J(H,H) = 5.7 Hz) and the multiplet a δH 8.20 are for the ortho pyridine signals of 2a and 2b, respectively. The diastereotopic methylene protons of the ampy ligand appear as two doublets at δ 4.10 and 3.92 (d, 2J(H,H) = 16.1 Hz) for the cationic complex 2a, while the cis derivative 2b displays these signals at δ 4.48 and 4.42. Control 1H NMR experiments show that adding sodium acetate (1.0 and 3.5 equiv) to the 2a,b mixture in CD3OD showed a progressive increase in the signal at δ 1.93 attributed to the free acetate of the cationic derivative 2a, confirming the proposed structure (see Figure S10 in the Supporting Information), as observed for [Ru(κ2-OAc)(PPh3)(NN)(CO)]OAc (NN = en, ampy).22 Finally, in the 13C{1H} NMR spectrum the carbonyl acetate carbon atoms of the cationic 2a are at δ 190.3 and 180.3, while the acetate resonances of the cis derivative 2b are at δ 191.7 and 190.4.
The reaction of [Ru(κ2-OAc)2(PPh3)2] with ampyrim12 leads to species similar to those observed with ampy. Thus, the complex trans,cis-[Ru(κ1-OAc)2(PPh3)2(ampyrim)] (3) is quickly obtained from [Ru(κ2-OAc)2(PPh3)2] and ampyrim in MEK at room temperature and isolated in 88% yield (Scheme 1). Complex 3 isomerizes in methanol at RT within 48 h, leading to a 2:1 mixture of the cationic complexes cis-[Ru(κ2-OAc)(PPh3)2(ampyrim)]OAc (3a) and cis,cis-[Ru(κ1-OAc)2(PPh3)2(ampyrim)] (3b), isolated in 78% yield (Scheme 1). The 31P{1H} NMR spectroscopic data of 3a,b resemble those of the analogue ampy derivatives 2a,b, with two doublets at δ 58.8 and 47.7 with 2J(P,P) = 32.8 Hz for 3a and at δ 64.3 and 49.0 with 2J(P,P) = 28.0 Hz for 3b.
Synthesis of Diacetate Ruthenium Complexes with Diphosphines and NN Ligands
The synthesis of Ru acetate complexes with the ligands dppm and dppe12 has been reported by Wong et al. by starting from [Ru(κ2-OAc)2(PPh3)2] and the diphosphines in toluene at reflux for 12 h. With dppm the cationic [Ru(κ2-OAc)(dppm)]OAc was isolated, whereas with dppe a mixture of the three isomers cis- and trans-[Ru(κ1-OAc)2(dppe)2] and the cationic [Ru(κ2-OAc)(dppe)]OAc were formed and were separated by fractional crystallization.32 A reexamination of this procedure under milder reaction conditions show that the trans-[Ru(κ1-OAc)2(P2)2] (P2 = dppm (4), dppe (5)) derivatives (δP −5.9 and 44.7, respectively) have been obtained as single products in 68% and 71% yields, respectively, by treatment of [Ru(κ2-OAc)2(PPh3)2] with 2 equiv of dppm or dppe in toluene at 95 °C for 20 min (eq 1).
 |
1 |
The reaction of [Ru(κ2-OAc)2(PPh3)2] with 1 equiv of dppm in MEK at room temperature afforded a mixture of trans-[Ru(κ1-OAc)2(dppm)2] (4) and the unreacted precursor. Addition of an excess of ampy (1.2 equiv) at RT results in a partial decoordination of dppm from 4, with the formation of trans-[Ru(κ1-OAc)2(dppm)(ampy)] in the presence of 4 in a 2:1 molar ratio, as inferred from NMR analysis (see Figures S23 and S24 in the Supporting Information). Interestingly, the thermodynamically most stable isomer, cis-[Ru(κ1-OAc)2(dppm)(ampy)] (6), has been isolated in 76% yield from [Ru(κ2-OAc)2(PPh3)2] and dppm (1 equiv) in toluene at reflux (4 h), followed by reaction with ampy at 95 °C for 12 h, via the intermediate [Ru(κ1-OAc)2(dppm)(PPh3)] species32 (Scheme 2).
Scheme 2. Synthesis of cis-[Ru(κ1-OAc)2(dppm)(ampy)] (6).
The 31P{1H} NMR spectrum of 6 in CDCl3 displays two doublets at δ 23.4 and 7.9 with 2J(P,P) = 94.4 Hz, whereas the methylene protons of the ampy ligand give a doublet of doublets at δH 3.58 (2J(H,H) = 16.1 Hz and 3J(H,H) = 5.0 Hz) and a multiplet at δH 3.32. A 15N–1H HSQC 2D NMR analysis reveals that the NH2 signals are at δ 9.74 and 1.13 ppm, consistent with the presence of one NH···O hydrogen bond interaction with one acetate. The 1H NMR spectrum of 6 in CD3OD shows two resonances at δ 2.03 and 1.66 for the methyl groups, indicating that the OAc ligands are coordinated, as was also confirmed by addition of NaOAc (1.0–3.5 equiv) to 6 (δH 1.92 for the free OAc) (see Figure S27 in the Supporting Information). Attempts to isolate the analogous dppe derivative by the reaction of [Ru(κ2-OAc)2(PPh3)2] with dppe in toluene and treatment with ampy failed, resulting in the formation of two [Ru(OAc)2(dppe)(ampy)] species in the presence of uncharacterized complexes (see Figures S31 and S32 in the Supporting Information). The employment of diphosphines with a longer backbone leads to the isolation of trans diphosphine/NN derivatives at room temperature. The reaction of [Ru(κ2-OAc)2(PPh3)2] with dppf in CH2Cl2 at RT for 1 h, followed by reaction with en for 30 min, affords the complex trans-[Ru(κ1-OAc)2(dppf)(en)] (7), isolated in 90% yield (Scheme 3).
Scheme 3. Synthesis of Neutral trans-[Ru(κ1-OAc)2P2(NN)] (P2 = Diphosphine) Complexes.
An X-ray diffraction experiment carried out for 7 shows that this complex crystallizes in a distorted-octahedral geometry with two trans acetate groups (Figure 1).
Figure 1.
ORTEP style plot of compound 7 in the solid state (CCDC 2058063). Ellipsoids are drawn at the 50% probability level. The phenyl groups are simplified as wireframes for clarity (as well as disorder of one phenyl group is not shown). Selected bond lengths (Å) and angles (deg): Ru1–O1 2.109(3), Ru1–O3 2.118(3), Ru1–N1 2.164(4), Ru1–N2 2.155(3), Ru1–P1 2.2934(11), Ru1–P2 2.2816(11), O1–Ru1–O3 174.90(10), O1–Ru1–N2 87.73(13), O3–Ru1–N2 92.89(13), O1–Ru1–N1 89.91(13), O3–Ru1–N1 85.28(13), N2–Ru1–N1 77.99(13), O1–Ru1–P2 92.37(8), O3–Ru1–P2 92.69(8), N2–Ru1–P2 89.74(9), N1–Ru1–P2 167.42(10), N2–Ru1–P2 89.74(9), N1–Ru1–P2 167.42(10), O1–Ru1–P1 95.44(8), O3–Ru1–P1 83.23(8), N2–Ru1–P1 171.04(10), N1–Ru1–P1 93.61(10), P2–Ru1–P1 98.48(4). Hydrogen-bond distances measured for O2···H1A and O4···H2A are 1.913 and 2.019 Å, respectively.
Complex 7 displays Ru–O (2.109(3), 2.118(3) Å) distances in line with the data reported for analogous monodentate diacetate ruthenium complexes,32,33 with the Ru–N (2.164(4), 2.155(3) Å) distances being slightly shorter in comparison to those of the related dichloride compound trans-[RuCl2(dppf)(en)] (Ru–N 2.167(3), 2.171(3) Å)) and consistent with the strong trans influence exerted by the diphosphine.32,34 The O1–Ru1–O3 angle is almost linear (174.90(10)°) and is greater with respect to that of the analogous chloride compound (Cl–Ru–Cl angle of 166.31(4)°). The solid-state study of 7 also revealed the presence of intramolecular hydrogen-bond interactions between the C=O acetate oxygen atoms with the axial N–H protons of the en ligand with O···H distances of 1.913 and 2.019 Å.23,33 The 1H NMR spectrum of 7 in solution (CD2Cl2) displays one triplet at δ 2.64 for the two CH2N groups and one broad signal for the four NH hydrogens, shifted to low field at δ 4.92, consistent with a hydrogen-bond interaction with the acetate. The ampy derivative trans-[Ru(κ1-OAc)2(dppp)(ampy)] (8) (85% yield) has been prepared from [Ru(κ2-OAc)2(PPh3)2] and dppp12 in CH2Cl2, followed by treatment with ampy at RT (Scheme 3, method 1). Alternatively, 8 (93% yield) has been obtained in acetone (method 2) and also by reaction of 2 with dppp in MEK (50 °C, 20 h), by PPh3 substitution (61% yield) (method 3). The 31P{1H} NMR spectrum of 8 displays two doublets at δ 47.8 and 33.1 with 2J(P,P) = 49.l Hz, while the NH2 protons give a broad singlet at δH 6.27, indicating a NH···O hydrogen bond. The diacetate derivatives trans-[Ru(κ1-OAc)2(dppb)(ampy)] (9) and trans-[Ru(κ1-OAc)2(dppf)(ampy)] (10) have been synthesized in 61–88% yields by the reaction of Ru(κ2-OAc)2(PPh3)2] with the corresponding diphosphine (dppb, dppf) and ampy in CH2Cl2 or acetone, following the procedure described for 8. Complexes 9 and 10 have also been prepared by starting from 2 and the diphosphine dppb or dppf, respectively, and isolated in 70–73% yield. Treatment of (R)-BINAP with [Ru(κ2-OAc)2(PPh3)2] in toluene at reflux for 24 h, followed by reaction with ampy (RT, 1 h), afforded trans-[Ru(κ1-OAc)2((R)-BINAP)(ampy)] (11) in 59% yield as a single stereoisomer (Scheme 3). The 31P{1H} NMR spectrum of 11 in CD2Cl2 exhibits two doublets at δ 54.9 and 40.9 with 2J(P,P) = 36.9 Hz, whereas the 1H NMR spectrum reveals two broad signals for the NH2 protons interacting with the acetate ligands at δ 6.91 and 5.06, as inferred from a 1H–15N HSQC 2D NMR analysis (see Figure S61 in the Supporting Information). In analogy to the ampy complexes, the ampyrim derivatives trans-[Ru(κ1-OAc)2P2(ampyrim)] (P2 = dppp (12), dppb (13), dppf (14)) have been isolated in good yield (77–85%) by reaction of [Ru(κ2-OAc)2(PPh3)2] with diphosphine and ampyrim in CH2Cl2 at RT (method 1 for 12–14). Alternatively, 12–14 have been prepared from 3 and a diphosphine in MEK at 50 °C (57–80% yields) (Scheme 3). Complex 12 shows two doublets at δP 47.9 and 32.6 with 2J(P,P) = 50.1 Hz, whereas the multiplets at δH 8.52 and 8.41 are ascribed to NCH protons of the pyrimidine. The chiral complex trans-[Ru(κ1-OAc)2((R)-BINAP)(ampyrim)] (15) (63% yield) has been synthesized from [Ru(κ2-OAc)2(PPh3)2] and (R)-BINAP in toluene at reflux and treatment with ampyrim in acetone at RT. Through a one-pot reaction trans-[Ru(κ1-OAc)2(dppb)(8-aminoquinoline)] (16) (90% yield) is obtained from [Ru(κ2-OAc)2(PPh3)2], dppb, and 8-aminoquinoline in CH2Cl2 at RT (Scheme 3). Complex 16 displays two doublets at δP 50.5 and 37.2 (2J(P,P) = 36.7 Hz), whereas the multiplet at δH 9.23 is attributed to the proton in position 2 of the 8-aminoquinoline, shifted to low field in comparison to the free ligand (δ 8.77),35 while the broad singlet at δH 8.24 is ascribed to the amino group.
The trans acetate derivatives trans-[Ru(κ1-OAc)2P2(NN)], bearing ampy-type ligands, isomerize to the thermodynamically most stable cationic complexes [Ru(κ2-OAc)P2(NN)]OAc in methanol, without formation of the neutral cis derivative. Thus, [Ru(κ2-OAc)(dppp)(ampy)]OAc (8a) is obtained in 90% yield by dissolution of 8 in MeOH at room temperature (Scheme 4).
Scheme 4. Synthesis of Cationic [Ru(κ2-OAc)P2(NN)]OAc (P2 = Diphosphine) Complexes.
Complex 8a shows in the 31P{1H} NMR spectrum in CD3OD two doublets at δ 55.2 and 36.7 with 2J(P,P) = 48.4 Hz. The doublet at δH 8.09 (3J(H,H) = 5.7 Hz) is ascribed to the ortho pyridine proton, while the two singlets at δH 1.52 and 1.92 are assigned to the methyl group of the coordinated and free acetates, respectively. The cationic complexes [Ru(κ2-OAc)P2(ampy)]OAc(P2 = dppb (9a), dppf (10a)) have been prepared from 9 and 10 in methanol at RT and isolated in 95–98% yields (Scheme 4). The 31P{1H} NMR spectra show the typical doublet patterns for the two complexes at δP 58.2 and 46.0 (2J(P,P) = 37.2 Hz) and at δP 59.9 and 49.5 (2J(P,P) = 35.4 Hz) for 9a and 10a, respectively. The 1H NMR spectra of these complexes in CD3OD show diastereotopic CH2N protons (δ 4.03 and 3.60, with 2J(H,H) = 16.4 Hz for 9a) and a singlet at δ 1.92 for the methyl group of the free acetate, as for 8a. The coordinated acetate ligands of 9a and 10a appear as doublets at δC 189.7 and 190.8, while the free acetate appears at δC 180.4. In a similar way the cationic ampyrim derivatives [Ru(κ2-OAc)P2(ampyrim)]OAc (P2 = dppp (12a), dppb (13a), dppf (14a)) have been quantitatively isolated (87–98% yield) from the corresponding trans isomers in CH3OH, the NMR data resembling those of the analogous ampy complexes. The isomerization of the BINAP derivatives 11 and 15 in methanol at RT leads to the cationic [Ru(κ2-OAc)((R)-BINAP)(NN)]OAc (NN = ampy (11a), ampyrim (15a)) in 86–96% yields as a mixture of two isomers in about a 2:1 molar ratio for 11a and 1:1 for 15a, respectively (Scheme 4), as inferred from NMR measurements in CD3OD. Complex 11a shows a two doublets at δP 61.1 and 52.4 (2J(P,P) = 38.8 Hz) for the major isomer and two doublets at δP 68.3 and 58.1 (2J(P,P) = 38.7 Hz) for the minor species. Finally, the two singlets at δH 1.50 and 1.41 are assigned to the methyl acetate ligands of the two isomers, whereas the signal at δH 1.92 is assigned to the free acetate.
Synthesis of Dipivalate Ruthenium Complexes with PPh3 and ampy
The precursor [Ru(κ2-OPiv)2(PPh3)2] (17) has been isolated in 75% yield by treatment of [RuCl2(PPh3)3] with sodium pivalate in tert-butyl alcohol at 70 °C by a slight modification of the synthesis reported by Wilkinson3d (Scheme 5).
Scheme 5. Synthesis of the Pivalate 17 and the ampy Derivative 18.
Reaction of 17 with ampy in chloroform at RT affords the pivalate ruthenium derivative trans,cis-[Ru(κ1-OPiv)2(PPh3)2(ampy)]12 (18), isolated in 85% yield (Scheme 5). Complex 18 shows two 31P{1H} NMR doublets at δ 45.8 and 38.5 with 2J(P,P) = 30.5 Hz. The ampy NCH2 protons appear as a broad multiplet at δH 4.03, with the NH2 signal superimposed on those of the aromatic protons, in agreement with a NH···O interaction, whereas the pivalate CO groups give a doublet at δC 188.2 (3J(C,P) = 1.3 Hz).
Synthesis of Pincer CNN Ruthenium Acetate Complexes
The pincer acetate complex [Ru(κ1-OAc)(CNNOMe)(PPh3)2] (19) has been easily prepared in 75% yield by treatment of [Ru(κ2-OAc)2(PPh3)2] with the ligand HCNNOMe 12 in the presence of the weak base NEt3 (10 equiv) in 2-propanol at reflux, through the elimination of acetic acid and cyclometalation (Scheme 6).
Scheme 6. Synthesis of Pincer CNN Ruthenium Acetate Complexes.
The 31P{1H} NMR spectrum of 19 in CD2Cl2 shows two doublets at δ 57.2 and 52.9 with 2J(P,P) = 33.3 Hz, whereas the signals of the NH2 group are at δH 8.86 and 1.92. The low-field resonance is consistent with an intramolecular NH···O hydrogen bond interaction with the acetate ligand (see Figure 117 in the Supporting Information). The singlet at δ 7.68 is attributed to the CH proton close to the ortho-metalated carbon atom, while the diastereotopic CH2N gives a doublet of doublets at δ 4.09 (2J(H,H) = 17.3 Hz and 3J(H,H) = 6.0 Hz) and a multiplet at δ 3.42. Finally, the cyclometalated carbon appears at δC 185.5 (dd with 2J(C,P) = 14.3 and 8.4 Hz), whereas the signal at δ 180.1 can be attributed to the carboxylate CO group. Accordingly, the diphosphine pincer complex [Ru(κ1-OAc)(AMTP)(dppb)] (20) (85% yield) has been obtained from [Ru(κ2-OAc)2(dppb)] with HAMTP12 and NEt3 in 2-propanol at reflux (Scheme 6). Alternatively, 20 can be prepared (46% yield) directly from [Ru(κ2-OAc)2(PPh3)2], dppb, and HCNN, through a one-pot reaction. Notably, this new route is more straightforward for preparative scope, with respect to that described, involving the protonation with HOAc of the air- and moisture-sensitive isopropoxide [Ru(OiPr)(AMTP)(dppb)], which equilibrates with the hydride complex [RuH(AMTP)(dppb)].25 Similarly to 20, the benzo[h]quinoline CNN derivative [Ru(κ1-OAc)(AMBQPh)(dppb)] (21) (59% yield) was obtained from [Ru(κ2-OAc)2(dppb)], HAMBQPh,12 and NEt3 in 2-propanol at reflux (Scheme 6). Conversely, 21 (65% yield) can also be synthesized by a one-pot reaction from [Ru(κ2-OAc)2(PPh3)2], dppb, and HAMBQPh. In CD2Cl221 shows two doublets at δP 59.8 and 44.9 with 2J(P,P) = 37.9 Hz, while the NH2 resonances are at δH 8.61 and 0.98, consistent with a N–H···O interaction as for 19 and 20.25 Finally, the broad singlet at δC 180.4 is assigned to the carboxylate, a value close to that of the doublet of doublets at δC 180.3 with 2J(C,P) = 16.1 and 8.8 Hz for the Ru–C atom.
Catalytic Reduction of Carbonyl Compounds via TH and HY Reactions
The acetate complexes display good to high catalytic activity in the reduction of the C=O bond with 2-propanol in the presence of base and H2 under pressure (S/C = 1000–10000) (Scheme 7).
Scheme 7. TH and HY of Ketones and Aldehydes Catalyzed by Ruthenium Diacetate Complexes 7–11, 16, and 21.
The ethylenediamine dppf derivative 7 displays poor activity in the TH of model substrate acetophenone a (0.1 M) in 2-propanol at reflux with NaOiPr (2 mol %), affording 1-phenylethanol (59% of conversion) in 20 h at S/C = 2000 (Table 1, entry 1). Conversely, the related ampy complex 10 shows a significantly higher activity with S/C = 10000, leading to 90% of the alcohol in 3 h (TOF = 28000 h–1; entry 7). The ampy compounds 8 and 9, bearing the dppp and dppb ligands, give 95% and 87% conversion of a in 3 and 20 h, respectively, at S/C = 10000 (entries 2 and 3). The use of a higher amount of 9 (S/C = 2000) leads to a dramatic increase in the activity (90% conversion in 10 min, TOF = 11000 h–1; entry 4), thus indicating that the dppb derivative undergoes easier deactivation with respect to the ferrocenyl diphosphine complex.
Table 1. Catalytic TH of Acetophenone a (0.1 M) with Complexes 7–11 and 21 (S/C = 2000–10000) and NaOiPr (2 mol %) in 2-Propanol at 82 °C.
| entry | complex | S/C | time | conversiona (%) | TOFb (h–1) |
|---|---|---|---|---|---|
| 1 | 7 | 2000 | 20 h | 59 | 70 |
| 2 | 8 | 10000 | 4 h | 95 | 5200 |
| 3 | 9 | 10000 | 20 h | 87 | 1200 |
| 4 | 9 | 2000 | 10 min | 90 | 11000 |
| 5 | 9a | 10000 | 20 h | 87 | 1300 |
| 6 | 9a | 2000 | 20 min | 93 | 21000 |
| 7 | 10 | 10000 | 3 h | 90 | 28000 |
| 8 | 11 | 2000 | 5 h | 94 | 6400c |
| 9 | 21 | 10000 | 20 min | 97 | 160000 |
Conversions have been determined by GC analyses.
Turnover frequency (moles of ketone converted to alcohol per mole of catalyst per hour) at 50% conversion.
30% ee.
The cationic dppb derivative 9a shows an activity (87% and 93% conv. at S/C 10000 and 2000) comparable with that of 9, suggesting that under these catalytic conditions the neutral trans9 and the cationic 9a lead to the same catalytically active species (Table 1, entries 3–6). Use of the (R)-BINAP complex 11 (S/C = 2000) affords 94% conversion in 5 h, but with poor enantioselectivity (30% ee; entry 8), while the 8-aminoquinoline derivative 16 gives incomplete reduction (29% conversion in 5 h). Finally, the pincer complex 21 was proven to be highly efficient in the TH of a, giving quantitative conversion in 20 min at S/C = 10000 and TOF = 160000 h–1 (entry 9), a value comparable to that observed using the corresponding chloride-containing complex.20b,20c,25 Catalysts 8, 10, and the pincer 21 were tested in the reduction of (bulky) ketones. Thus, 8 and 10 (at S/C = 5000) catalyze the quantitative reduction of tert-butyl phenyl ketone b to 2,2-dimethyl-1-phenyl-1-propanol in 18 and 20 h, respectively (Table 2, entries 1 and 2), whereas the pincer CNN compound 21 leads to 90% conversion in 18 h, with rates lower than those observed for the TH of a (entry 3). Benzophenone c was converted to benzhydrol (86 and 78% yields) at S/C = 10000 in 18–20 h with 8 and 10 (entries 4 and 5), whereas with the pincer 21 the reaction is faster with 85% conversion in 2 h (entry 6). Complex 8 catalyzes the TH of d, leading to cyclohexanol (98% conversion) at S/C = 5000 in 1.5 h (TOF = 19000 h–1, entry 7), while with 10 and 21, substrate d is quantitatively reduced in 10 and 5 min, respectively, with TOF values of 30000 and 150000 h–1, which much of the same values obtained for a (entries 8 and 9). Complexes 8 and 10 promote the reduction of (−)-menthone e to (+)-neomenthol as the main isomer in 58 and 65% yields, in addition to (+)-isomenthol, (−)-menthol, and (+)-neoisomenthol (entries 10 and 11).
Table 2. Catalytic TH of Carbonyl Compounds (0.1 M) to Alcohols with Complexes 8, 10, and 21 (S/C = 2000–10000) and NaOiPr (2 mol %) in 2-Propanol at 82 °C.
| entry | substrate | complex | S/C | time | conversiona (%) | TOFb (h–1) |
|---|---|---|---|---|---|---|
| 1 | b | 8 | 5000 | 20 h | 96 | 700 |
| 2 | b | 10 | 5000 | 18 h | 98 | 1800 |
| 3 | b | 21 | 5000 | 18 h | 99 | 2500 |
| 4 | c | 8 | 10000 | 20 h | 86 | 1800 |
| 5 | c | 10 | 10000 | 18 h | 78 | 19000 |
| 6 | c | 21 | 10000 | 2 h | 85 | 59000 |
| 7 | d | 8 | 5000 | 1.5 h | 98 | 19000 |
| 8 | d | 10 | 5000 | 10 min | 98 | 30000 |
| 9 | d | 21 | 5000 | 5 min | 99 | 150000 |
| 10 | e | 8 | 2000 | 20 h | 86c | 1100 |
| 11 | e | 10 | 2000 | 18 h | 98d | 7000 |
Conversions have been determined by GC analyses.
Turnover frequency (moles of ketone converted to alcohol per mole of catalyst per hour) at 50% conversion.
Mixture of diastereoisomeric alcohols: (+)-neomenthol (58%), (+)-isomenthol (11%), (−)-menthol (15%), (+)-neoisomenthol (16%).
Mixture of diastereoisomeric alcohols: (+)-neomenthol (65%), (+)-isomenthol (11%), (−)-menthol (15%), (+)-neoisomenthol (9%).
A comparison of the activity of the acetate vs the analogous chloride complexes show that the latter undergo a slightly shorter induction period for the formation of the catalytically active species with NaOiPr, whereas the productivity depends on the stereoelectronic properties of the diphosphine, dppf being strongly beneficial to achieving efficient TH.19a,19d
Complexes 7, 9, 10, and 19 were also studied in the hydrogenation (HY) of ketones and aldehydes (2 M) at 20–30 atm of H2 pressure and 40–70 °C in ethanol or methanol with KOtBu at S/C values of up to 10000 (Scheme 7). The HY reactions have been carried out in a catalyst screening system (eight-vessels Endeavor Biotage system), which allows parallel reactions to be followed.
The en and ampy derivatives 7 and 10 catalyze the quantitative HY of a at 40 °C under 30 atm of H2 pressure with S/C = 10000 in EtOH (Table 3, entries 1 and 2), whereas the pincer 19 shows low activity (40% conversion) at 70 °C (entry 3). Complex 9 catalyzes the HY of benzaldehyde f with low conversion (55%) at 50 °C in MeOH (S/C = 1000) (entry 4). Conversely, 9 promotes the complete HY of trans-cinnamaldehyde g, affording cinnamyl alcohol (93%) as the main product of the C=O reduction and 3-phenylpropan-1-ol (6%) as a byproduct of the additional C=C HY (entry 5). In addition, the cationic isomer 9a displays very poor activity in the HY of f in MeOH with 12% conversion.
Table 3. HY of Carbonyl Compounds (2 M) with Complexes 7, 9, 10, and 19 under H2 with KOtBu (2 mol %) after 16 h.
| entry | complex | substrate | S/C | solvent | T (°C) | p(H2) (atm) | conversiona (%) | alcohola (%) | byproductsa (%) |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 7 | a | 10000 | EtOH | 40 | 30 | 99 | 99 | |
| 2 | 10 | a | 10000 | EtOH | 40 | 30 | 99 | 99 | |
| 3 | 19 | a | 10000 | EtOH | 70 | 30 | 40 | 40 | |
| 4 | 9 | f | 1000 | MeOH | 50 | 20 | 56 | 55 | |
| 5 | 9 | g | 1000 | MeOH | 50 | 20 | >99 | 93 | 6b |
The HY experiments were carried out in an eight-vessel Endeavor Biotage system, and the conversions were determined by GC analysis.
3-phenylpropan-1-ol.
With regard to the mechanism of the TH and HY reductions, it is likely that the catalytically active mono- or dihydride Ru species are obtained from the ruthenium carboxylate precursors by reaction with alkoxides or H2.36 For the TH reactions in 2-propanol, the presence of an amino group cis to the Ru carboxylate allows the easy formation of Ru–H species via a Ru amide complex and alcohol37 or via a Ru amine/alkoxide intermediate.37−40 In the HY reactions in basic alcohol media, H2 splitting leads to the formation of the ruthenium hydride active species from the carboxylate precursor through a 16-electron Ru amide complex38b,38c or via a Ru amine/alkoxide derivative.39 The CNN pincer derivatives undergo elimination of the labile carboxylate group, affording the corresponding hydride species, i.e. [RuH(CNN)(dppb)], a reaction which is facilitated by the cis NH2 function.38a,40 The low activity of the PPh3 pincer derivatives in HY may be ascribed to the formation of trans-[RuH(CNNOMe)(PPh3)2], in which the H is trans to N, with respect to the more active [RuH(CNN)(dppb)], where H is trans to P, affording a more hydridic hydride species (see Figure S127 in the Supporting Information).19d,41
Concluding Remarks
In conclusion, we have described the preparation of a class of carboxylate ruthenium complexes containing PPh3 and diphosphines in combination with bidentate NN ligands. Neutral trans and cis complexes of the formula [Ru(OCOR)2P2(NN)] and the cationic complexes [Ru(O2CR)P2(NN)](O2CR) have been isolated through straightforward syntheses from [Ru(κ2-OCOR)2(PPh3)2], a diphosphine, and NN ligands. While the trans diamine derivatives [Ru(κ1-OAc)2P2(en)] are thermally stable, the related 2-(aminomethyl)pyridine-type complexes trans-[Ru(κ1-OAc)2P2(NN)] easily undergo isomerization at room temperature to the more stable cis-[Ru(κ1-OAc)2P2(NN)] and/or the cationic [Ru(κ1-OAc)P2(NN)]OAc complexes in methanol. In addition, pincer complexes of the formula [Ru(κ1-OAc)(CNN)P2] have been obtained from [Ru(κ2-OAc)2(PPh3)2] via facile cyclometalation of HCNN ligands, and with an additional diphosphine, through a one-pot reaction. The described complexes show good to high catalytic activity in the transfer hydrogenation and hydrogenation of carbonyl compounds. Studies to extend this protocol to the preparation of ruthenium carboxylate complexes with NN and CNN pincer ligands and their application in catalytic organic transformations are currently in progress.
Experimental Section
All reactions were carried out under an argon atmosphere using standard Schlenk techniques. The solvents were carefully dried by standard methods and distilled under argon before use. The ruthenium complexes [RuCl2(PPh3)3],42 [Ru(κ2-OAc)2(PPh3)2],3d and [Ru(κ2-OAc)2(dppb)]32 and the ligands HAMTP,20h HCNNOMe,20a and HAMBQPh 20b were prepared according to literature procedures, whereas all other chemicals were purchased from Aldrich and Strem and used without further purification. NMR measurements were recorded on Bruker AC 200 and Avance III HD NMR 400 spectrometers. Chemical shifts (ppm) are relative to TMS for 1H and 13C{1H}, whereas H3PO4 was used for 31P{1H}. Infrared measurements were obtained with a Bruker Vector 22 FTIR spectrometer. Elemental analyses (C, H, N) were carried out with a Carlo Erba 1106 analyzer, whereas GC analyses were performed with a Varian CP-3380 gas chromatograph equipped with a 25 m length MEGADEX-ETTBDMS-β chiral column with hydrogen (5 psi) as the carrier gas and a flame ionization detector (FID).
Synthesis of trans,cis-[Ru(κ1-OAc)2(PPh3)2(en)] (1)
[Ru(κ2-OAc)2(PPh3)2] (100 mg, 0.134 mmol) and en (9.6 μL, 0.142 mmol, 1.06 equiv) were stirred in MEK (2 mL) at room temperature for 45 min. Addition of n-pentane (2 mL) afforded a yellow precipitate that was filtered, washed with n-pentane (2 mL), and dried under reduced pressure. Yield: 90 mg (84%). Anal. Calcd for C42H44N2O4P2Ru (803.84): C, 62.76; H, 5.52; N, 3.49. Found: C, 62.85; H, 5.60; N, 3.51. 1H NMR (200.1 MHz, CDCl3, 20 °C): δ 7.34–6.97 (m, 30H; aromatic protons), 5.31 (br s, 4H: NH2), 2.67 (br s, 4H; CH2N), 1.67 (s, 6H; OCOCH3). 31P{1H} NMR (81.0 MHz, CDCl3, 20 °C): δ 45.5 (s). 1H NMR (400.1 MHz, CD2Cl2, 25 °C): δ 7.42–7.23 (m, 18H; aromatic protons), 7.16 (t, 3J(H,H) = 7.4 Hz, 12H; aromatic protons), 5.37 (br s, 4H; NH2), 2.70 (m, 4H; NCH2CH2N), 1.71 (s, 6H; OCOCH3). 13C{1H} NMR (100.6 MHz, CD2Cl2, 25 °C): δ 182.7 (br s; OCOCH3), 136.0 (t, 1J(C,P) = 18.7 Hz; ipso-Ph), 135.6 (t, 1J(C,P) = 18.5 Hz; ipso-Ph), 134.2 (t, 2J(C,P) = 4.8 Hz; ortho-Ph), 128.8 (br s; para-Ph), 127.5 (t, 3J(C,P) = 4.4 Hz; meta-Ph), 43.9 (br s; NCH2CH2N), 25.8 (br s; OCOCH3). 31P{1H} NMR (162.0 MHz, CD2Cl2, 25 °C): δ 44.8 (s).
Synthesis of trans,cis-[Ru(κ1-OAc)2(PPh3)2(ampy)] (2)
Method 1
Complex 2 was prepared by following the procedure used for the synthesis of 1, with ampy (15.0 μL, 0.146 mmol, 1.09 equiv) in place of en. Yield: 113 mg (99%). Anal. Calcd for C46H44N2O4P2Ru (851.89): C, 64.86; H, 5.21; N, 3.29. Found: C, 64.90; H, 5.30; N, 3.31. 1H NMR (200.1 MHz, CD2Cl2, 20 °C): δ 8.45 (d, 3J(H,H) = 5.7 Hz, 1H; ortho-CH of C5H4N), 7.57–6.88 (m, 32H; aromatic protons), 6.70 (br d, 3J(H,H) = 5.4 Hz, 2H; NH2), 6.53 (pseudo-t, J(H,H) = 6.5 Hz, 1H; aromatic proton), 4.18 (m, 2H; CH2N), 1.67 (s, 6H; OCOCH3). 13C{1H} NMR (50.3 MHz, CD2Cl2, 20 °C): δ 180.9 (d, 3J(C,P) = l.6 Hz; OCOCH3), 166.5 (dd, 3J(C,P) = 2.5 Hz, 3J(C,P) = 1.4 Hz; NCCH2), 156.7 (d, 3J(C,P) = 4.0 Hz; NCH of C5H4N), 137.2–119.3 (m; aromatic carbon atoms), 51.6 (dd, 3J(C,P) = 3.5 Hz, 3J(C,P) = 2.4 Hz; CH2N), 26.1 (s; OCOCH3). 31P{1H} NMR (81.0 MHz, CD2Cl2, 20 °C): δ 44.6 (d, 2J(P,P) = 31.3 Hz), 39.4 (d, 2J(P,P) = 31.3 Hz).
Method 2
[Ru(κ1-OAc)2(PPh3)2] (37 mg, 0.050 mmol) and ampy (6.0 μL, 0.058 mmol, 1.17 equiv) were dissolved in CD2Cl2 (0.45 mL). After 5 min at room temperature quantitative formation of 2 was observed by NMR analysis.
Method 3
[RuCl2(PPh3)3] (450 mg, 0.469 mmol) and NaOAc (385 mg, 4.69 mmol, 10 equiv) were suspended in degassed acetone (5 mL), and the mixture was refluxed for 3 h, affording a bright orange precipitate of [Ru(κ2-OAc)2(PPh3)2]. When the reaction mixture was cooled to room temperature, ampy (52 μL, 0.504 mmol, 1.07 equiv) was added and the mixture was stirred for 30 min, leading to a bright yellow precipitate. After the addition of n-heptane (8 mL), the solid was filtered, washed with water (3 × 10 mL), 2-propanol (1 mL), and n-pentane (3 × 5 mL), and dried under reduced pressure. Yield: 303 mg (76%).
Synthesis of cis-[Ru(κ2-OAc)(PPh3)2(ampy)]OAc (2a) and cis,cis-[Ru(κ1-OAc)2(PPh3)2(ampy)] (2b)
Method 1
Complex 2 (20 mg, 0.023 mmol) was dissolved in CH3OH (2 mL), and the orange solution was stirred for 24 h at RT. The solvent was evaporated under reduced pressure, and the residue was dissolved in CH2Cl2 (0.5 mL). Addition of n-pentane (2 mL) gave a yellow-orange precipitate, which was filtered, washed with n-pentane (3 × 2 mL), and dried under reduced pressure. The product consists of 2a,b in a 3:2 molar ratio. Yield: 17 mg (85%). Anal. Calcd for C46H44N2O4P2Ru (851.89): C, 64.86; H, 5.21; N, 3.29. Found: C, 64.80; H, 5.17; N, 3.37. 1H NMR (400.1 MHz, CD3OD, 25 °C): δ 8.20 (m, 1H; ortho-CH of C5H4N minor isomer), 7.98 (d, 3J(H,H) = 5.7 Hz, 1H; ortho-CH of C5H4N major isomer), 7.73 (td, 3J(H,H) = 7.7 Hz, 4J(H,H) = 1.8 Hz, 1H; para-CH of C5H4N major isomer), 7.70–7.63 (m, 3H; aromatic protons both isomers), 7.62–7.49 (m, 4H; aromatic protons both isomers), 7.48–7.08 (m, 22H; aromatic protons both isomers), 6.96 (t, 3J(H,H) = 6.4 Hz, 1H; meta-CH of C5H4N major isomer), 6.73 (d, 3J(H,H) = 6.0 Hz, 1H; meta-CH of C5H4N minor isomer), 5.84 (ddd, 3J(H,H) = 7.6 Hz, 3J(H,H) = 5.8 Hz, 4J(H,H) = 1.6 Hz, 1H; meta-CH of C5H4N minor isomer), 4.48 (d, 2J(H,H) = 15.5 Hz, 1H; CH2N minor isomer), 4.42 (dd, 2J(H,H) = 15.5 Hz, 4J(H,P) = 4.6 Hz, 1H; CH2N minor isomer), 4.10 (d, 2J(H,H) = 16.1 Hz, 1H; CH2N major isomer), 3.92 (d, 2J(H,H) = 16.1 Hz, 1H; CH2N major isomer), 1.93 (s, 3H; OCOCH3 major isomer), 1.70 (s, 3H; OCOCH3 minor isomer), 1.36 (s, 3H; OCOCH3 minor isomer), 1.15 (s, 3H; OCOCH3 major isomer). 13C{1H} NMR (100.6 MHz, CD3OD, 25 °C): δ 191.7 (d, 2J(C,P) = 2.2 Hz; OCOCH3 minor isomer), 190.4 (br s; OCOCH3 minor isomer), 190.3 (br s; OCOCH3 major isomer), 180.3 (br s; OCOCH3 major isomer), 165.3 (d, 3J(C,P) = 1.6 Hz; NCCH2 minor isomer), 162.1 (d, 3J(C,P) = 1.4 Hz; NCCH2 major isomer), 160.7 (d, 3J(C,P) = 2.3 Hz; NCH of C5H4N minor isomer), 151.4 (br s; NCH of C5H4N major isomer), 138.9–121.7 (m; aromatic carbon atoms both isomers), 53.6 (d, 3J(C,P) = 2.9 Hz; CH2N major isomer), 51.2 (d, 3J(C,P) = 2.3 Hz; CH2N minor isomer), 24.3 (br s; OCOCH3 major isomer), 24.2 (m; OCOCH3 both isomers), 24.0 (d, 4J(C,P) = 1.5 Hz; OCOCH3 minor isomer). 31P{1H} NMR (162.0 MHz, CD3OD, 25 °C): δ 65.3 (d, 2J(P,P) = 29.3 Hz; minor isomer), 60.6 (d, 2J(P,P) = 32.6 Hz; major isomer), 49.4 (d, 2J(P,P) = 29.3 Hz; minor isomer), 47.4 (d, 2J(P,P) = 32.6 Hz; major isomer).
Method 2
[Ru(κ1-OAc)2(PPh3)2](20 mg, 0.0269 mmol) and ampy (3.0 μL, 0.0291 mmol, 1.08 equiv) were dissolved in CH3OH (2 mL), and the mixture was stirred for 36 h at RT. The solvent was evaporated under reduced pressure, and the residue was dissolved in CH2Cl2 (0.5 mL). Addition of n-pentane (2 mL) afforded a yellow-orange precipitate that was filtered, washed with n-pentane (3 × 2 mL), and dried under reduced pressure, leading to 2a,b in a 3:2 molar ratio. Yield: 19 mg (83%).
Synthesis of trans,cis-[Ru(κ1-OAc)2(PPh3)2(ampyrim)] (3)
Complex 3 was prepared byfollowing the procedure used for the synthesis of 1 (method 1), with ampyrim43 (16.1 μL, 0.168 mmol, 1.25 equiv) in place of en. Yield: 101 mg (88%). Anal. Calcd for C45H43N3O4P2Ru (852.87): C, 63.37; H, 5.08; N, 4.93. Found: C, 63.45; H, 5.10; N, 4.91. 1H NMR (200.1 MHz, CDCl3, 20 °C): δ 8.49 (m, 1H; RuNCH of C4H3N2), 8.36 (m, 1H; NCH of C4H3N2), 7.48–7.06 (m, 24H: aromatic protons), 7.05–6.88 (m, 6H: aromatic protons), 6.48 (pseudo-t, J(H,H) = 5.1 Hz, 1H: aromatic proton), 6.22 (m, 2H; NH2), 4.31 (m, 2H; CH2N), 1.71 (s, 6H; OCOCH3). 13C{1H} NMR (50.3 MHz, CDCl3, 20 °C): δ 180.9 (br s; OCOCH3), 176.3 (dd, 3J(CP) = 3.5 Hz, 3J(CP) = 1.4 Hz; NCCH2), 162.6 (d, 3J(CP) = 3.3 Hz; RuNCH of C4H3N2), 155.1 (s; NCH of C4H3N2), 136.3–117.6 (m; aromatic carbon atoms), 51.5 (t, 3J(CP) = 2.4 Hz; CH2N), 25.9 (s; OCOCH3). 31P{1H} NMR (81.0 MHz, CDCl3, 20 °C): δ 43.6 (d, 2J(P,P) = 32.3 Hz), 39.7 (d, 2J(P,P) = 32.3 Hz).
Synthesis of cis-[Ru(κ2-OAc)(PPh3)2(ampyrim)]OAc (3a) and cis,cis-[Ru(κ1-OAc)2(PPh3)2(ampyrim)] (3b)
Complex 3 (27 mg, 0.032 mmol) was dissolved in CH3OH (2 mL), and the orange solution was stirred for 48 h at RT. The solvent was evaporated under reduced pressure, and the residue was dissolved in CH2Cl2 (0.5 mL). Addition of n-pentane (2 mL) afforded a yellow-orange precipitate that was filtered, washed with n-pentane (3 × 2 mL), and dried under reduced pressure. The product consists of 3a,b in a 2:1 molar ratio. Yield: 21 mg (78%). Anal. Calcd for C45H43N3O4P2Ru (852.87): C, 63.37; H, 5.08; N, 4.93. Found: C, 63.35; H, 5.14; N, 4.97. 1H NMR (400.1 MHz, CD3OD, 25 °C): δ 8.82 (d, 3J(H,H) = 5.0 Hz, 1H; RuNCH of C4H3N2 minor isomer), 8.66 (dd, 1H, 3J(H,H) = 4.9 Hz, 4J(H,H) = 2.1 Hz; RuNCH of C4H3N2 major isomer), 8.25 (dt, 3J(H,H) = 5.1 Hz, 4J(H,H) = 2.4 Hz, 1H; NCH of C4H3N2 major isomer), 8.21 (dd, 3J(H,H) = 4.8 Hz, 4J(H,H) = 2.0 Hz, 1H; NCH of C4H3N2 minor isomer), 7.61 (t, 3J(H,H) = 8.6 Hz, 4H; aromatic protons major isomer), 7.43–7.33 (m, 6H; aromatic protons both isomers), 7.33–7.09 (m, 20H; aromatic protons both isomers), 7.06 (t, 3J(H,H) = 5.4 Hz, 1H; aromatic proton major isomer), 7.03 (m, 1H; aromatic proton minor isomer), 6.90 (d, 3J(H,H) = 6.3 Hz, 1H; aromatic proton minor isomer), 5.98 (t, 3J(H,H) = 5.4 Hz, 1H; aromatic proton minor isomer), 4.54–4.41 (m, 2H; CH2N minor isomer), 4.17 (d, 2J(H,H) = 17.1 Hz, 1H; CH2N major isomer), 3.96 (d, 2J(H,H) = 17.1 Hz, 1H; CH2N major isomer), 1.91 (s, 3H; OCOCH3 major isomer), 1.75 (s, 3H; OCOCH3 minor isomer), 1.36 (s, 3H; OCOCH3 minor isomer), 1.18 (s, 3H; OCOCH3 major isomer). 13C{1H} NMR (100.6 MHz, CD3OD, 25 °C): δ 192.2 (d, 2J(C,P) = 2.1 Hz; OCOCH3 minor isomer), 190.9 (br s; OCOCH3 minor isomer), 190.8 (br s; OCOCH3 major isomer), 180.0 (br s; OCOCH3 major isomer), 174.2 (d, 3J(C,P) = 1.6 Hz; NCCH2 minor isomer), 172.2 (d, 3J(C,P) = 1.5 Hz; NCCH2 major isomer), 167.0 (d, 3J(C,P) = 1.5 Hz; RuNCH of C4H3N2 minor isomer), 158.7 (s; RuNCH of C4H3N2 major isomer), 158.5 (s; NCH of C4H3N2 major isomer), 156.4 (s; NCH of C4H3N2 minor isomer), 136.4–129.4 (m; aromatic carbon atoms both isomers), 122.4 (d, J(C,P) = 1.5 Hz; aromatic carbon atom major isomer), 120.4 (br s; aromatic carbon atom minor isomer), 53.9 (d, 3J(C,P) = 2.0 Hz; CH2N major isomer), 51.7 (d, 3J(C,P) = 2.2 Hz; CH2N minor isomer), 24.3 (d, 4J(C,P) = 1.4 Hz; OCOCH3 minor isomer), 24.1 (br s; OCOCH3 both isomers), 23.9 (d, 4J(C,P) = 1.3 Hz; OCOCH3 major isomer). 31P{1H} NMR (162.0 MHz, CD3OD, 25 °C): δ 64.3 (d, 2J(P,P) = 28.0 Hz; minor isomer), 58.8 (d, 2J(P,P) = 32.8 Hz; major isomer), 49.0 (d, 2J(P,P) = 28.0 Hz; minor isomer), 47.7 (d, 2J(P,P) = 32.8 Hz; major isomer).
Synthesis of trans-[Ru(κ1-OAc)2(dppm)2] (4)
Complex 4 was prepared by following a slight modification of a procedure described for the synthesis of the cationic isomer [Ru(κ2-OAc)(dppm)2]OAc.32 [Ru(κ2-OAc)2(PPh3)2] (50.0 mg, 0.067 mmol) and dppm (51.9 mg, 0.135 mmol, 2.0 equiv) were stirred in toluene (0.75 mL) at 95 °C for 20 min. The solvent was evaporated under reduced pressure, and the residue was added to n-heptane (4 mL). The mixture was stirred for 10 min, giving a suspension, which was filtered; the solid was washed with n-heptane (2 × 1 mL) and n-pentane (2 × 1 mL) and dried under reduced pressure. Yield: 45 mg (68%). Anal. Calcd for C54H50O4P4Ru (987.96): C, 65.65; H, 5.10. Found: C, 65.70; H, 5.15. 1H NMR (200.1 MHz, CDCl3, 20 °C): δ 7.41–7.03 (m, 40H; aromatic protons), 5.84 (m, 4H; PCH2), 0.80 (s, 6H; OCOCH3). 31P{1H} NMR (81.0 MHz, CDCl3, 20 °C): δ - 5.9 (s).
Synthesis of trans-[Ru(κ1-OAc)2(dppe)2] (5)
Complex 5 was prepared by following the procedure used for the synthesis of 4, with dppe (53.8 mg, 0.135 mmol, 2.0 equiv) in place of dppm. This method presents some slight modifications in comparison to that already reported for the synthesis of 5.32 Yield: 49 mg (72%). Anal. Calcd for C56H54O4P4Ru (1016.01): C, 66.20; H, 5.36. Found: C, 66.26; H, 5.43. 1H NMR (200.1 MHz, CDCl3, 20 °C): δ 7.56–6.88 (m, 40H; aromatic protons), 3.20 (br m, 8H; PCH2CH2P), 0.80 (s, 6H; OCOCH3). 31P{1H} NMR (81.0 MHz, CDCl3, 20 °C): δ 44.7 (s).
Synthesis of cis-[Ru(κ1-OAc)2(dppm)(ampy)] (6)
[Ru(κ2-OAc)2(PPh3)2] (200 mg, 0.269 mmol) and dppm (104 mg, 0.270 mmol, 1.01 equiv) were dissolved in toluene (1 mL), and the mixture was refluxed for 4 h, until the precursor was fully converted to [Ru(κ1-OAc)2(dppm)(PPh3)] as verified by NMR analysis. ampy (31 μL, 0.300 mmol, 1.11 equiv) was added, and the solution was stirred at 95 °C for 14 h. The solvent was evaporated under reduced pressure, and the residue was added to n-heptane (6 mL). The suspension was stirred for 10 min, and the solid was filtered, washed with n-heptane (2 × 2 mL) and n-pentane (2 × 2 mL), and dried under reduced pressure. Yield: 145 mg (76%). Anal. Calcd for C35H36N2O4P2Ru (711.70): C, 59.07; H, 5.10; N, 3.94. Found C, 59.15; H, 5.18; N, 3.97. 1H NMR (200.1 MHz, CDCl3, 20 °C): δ 9.74 (m, 1H; NH2), 9.59 (m, 1H; ortho-CH of C5H4N), 8.01 (br t, 3J(H,H) = 8.1 Hz, 2H; aromatic protons), 7.92–6.86 (m, 19H; aromatic protons), 6.70 (t, 3J(H,H) = 7.5 Hz, 2H; aromatic protons), 5.84 (pseudo-q, J(H,H) = 13.1 Hz, 1H; PCH2), 5.11 (m, 1H; PCH2), 3.58 (dd, 2J(H,H) = 16.1 Hz, 3J(H,H) = 5.0 Hz, 1H; CH2N), 3.32 (m, 1H; CH2N), 2.01 (s, 3H; OCOCH3), 1.58 (s, 3H; OCOCH3), 1.13 (m, 1H; NH2). 31P{1H} NMR (81.0 MHz, CDCl3, 20 °C): δ 23.4 (d, 2J(P,P) = 94.4 Hz), 7.9 (d, 2J(P,P) = 94.4 Hz). 1H NMR (400.1 MHz, CD3OD, 20 °C): δ 9.19 (m, 1H; ortho-CH of C5H4N), 7.81 (t, 3J(H,H) = 15.3 Hz, 2H; aromatic protons), 7.64 (br t, 3J(H,H) = 16.2 Hz, 1H; aromatic proton), 7.51 (br t, 3J(H,H) = 13.6 Hz, 1H; aromatic proton), 7.44–6.90 (m, 17H; aromatic protons), 6.68 (t, 3J(H,H) = 14.9 Hz, 2H; aromatic protons), 5.92 (m, 1H; PCH2), 5.33 (m, 1H; PCH2), 3.61 (dd, 2J(H,H) = 16.2 Hz, 3J(H,H) = 5.6 Hz, 1H; CH2N), 2.35 (m, 1H; CH2N), 2.03 (s, 3H; OCOCH3), 1.66 (s, 3H; OCOCH3). 13C{1H} NMR (100.6 MHz, CD3OD, 20 °C): δ 181.5 (br s; OCOCH3), 178.4 (br s; OCOCH3), 162.5 (s; NCCH2), 154.5 (s; NCH of C5H4N), 138.5–120.1 (m; aromatic carbon atoms), 50.9 (t, 3J(C,P) = 5.6 Hz; CH2N), 27.0 (m; PCH2), 23.9 (s; OCOCH3), 22.6 (s; OCOCH3). 31P{1H} NMR (162.0 MHz, CD3OD, 20 °C): δ 21.1 (d, 2J(P,P) = 84.1 Hz), 7.4 (d, 2J(P,P) = 84.1 Hz).
Synthesis of trans-[Ru(κ1-OAc)2(dppf)(en)] (7)
[Ru(κ2-OAc)2(PPh3)2] (100 mg, 0.134 mmol) and dppf (75 mg, 0.135 mmol, 1.0 equiv) were dissolved in CH2Cl2 (1.5 mL) and stirred at room temperature for 1 h. After addition of ethylenediamine (en) (13 μL, 0.195 mmol, 1.46 equiv), the solution was stirred at room temperature for 30 min until a yellow precipitate was formed. n-Pentane (3 mL) was added to the mixture, which was stirred for 30 min and filtered, giving a yellow compound, which was washed with n-pentane (3 × 5 mL) and dried under reduced pressure. Yield: 101 mg (90%). Anal. Calcd for C40H42FeN2O4P2Ru (833.65): C, 57.63; H, 5.08; N, 3.36. Found: C, 57.65; H, 5.14; N, 3.40. 1H NMR (200.1 MHz, CD2Cl2, 20 °C): δ 7.69–7.55 (m, 8H; aromatic protons), 7.45–7.20 (m, 12H; aromatic protons), 4.92 (br s, 4H; NH2), 4.46 (m, 4H; C5H4), 4.24 (pseudo-t, J(H,H) = 1.8 Hz, 4H; C5H4), 2.64 (br t, J(H,H) = 4.6 Hz, 4H; NCH2CH2N), 1.69 (s, 6H; OCOCH3). 13C{1H} NMR (50.3 MHz, CD2Cl2, 20 °C): δ 182.0 (t, 3J(C,P) = 1.0 Hz; OCOCH3), 138.0 (pseudo-t, J(C,P) = 18.3 Hz; ipso-Ph), 134.5 (t, J(C,P) = 5.1 Hz; ortho-Ph), 129.3 (t, J(C,P) = 1.0 Hz; para-Ph), 127.7 (t, J(C,P) = 4.3 Hz; meta-Ph), 83.2 (pseudo-t, J(C,P) = 23.8 Hz; ipso-C5H4), 75.1 (t, J(C,P) = 4.0 Hz; C5H4), 71.6 (t, 3J(C,P) = 2.8 Hz; C5H4), 43.9 (m; CH2N), 26.0 (s; OCOCH3). 31P{1H} NMR (81.0 MHz, CD2Cl2, 20 °C): δ 48.3 (s).
Synthesis of trans-[Ru(κ1-OAc)2(dppp)(ampy)] (8)
Method 1
[Ru(κ2-OAc)2(PPh3)2] (100 mg, 0.134 mmol) and dppp (56.1 mg, 0.136 mmol, 1.01 equiv) were dissolved in CH2Cl2 (2 mL) and stirred at room temperature for 1 h. ampy (20 μL, 0.194 mmol, 1.45 equiv) was added to the mixture, and the resulting light orange solution was stirred for 1 h at room temperature. The solvent was removed under reduced pressure, n-pentane (5 mL) was added, and the suspension was stirred for 10 min. After filtration, the yellow product was washed with n-pentane (4 × 3 mL) and dried under reduced pressure. Yield: 84 mg (85%). Anal. Calcd for C37H40N2O4P2Ru (739.75): C, 60.07; H, 5.45; N, 3.79. Found: C, 60.12; H, 5.44; N, 3.83. 1H NMR (200.1 MHz, CD2Cl2, 20 °C): δ 8.42 (d, 3J(H,H) = 4.8 Hz, 1H; ortho-CH of C5H4N), 7.78–6.96 (m, 22H; aromatic protons), 6.71 (pseudo-t, J(H,H) = 6.5 Hz, 1H; aromatic proton), 6.28 (br s, 2H; NH2), 4.12 (br m, 2H; CH2N), 2.62–2.35 (m, 4H; PCH2), 2.30–1.80 (m, 2H; CH2), 1.68 (s, 6H; OCOCH3). 13C{1H} NMR (50.3 MHz, CD2Cl2, 20 °C): δ 180.9 (d, 3J(C,P) = 1.7 Hz; OCOCH3), 166.3 (dd, 3J(C,P) = 2.7 Hz, 3J(C,P) = 1.4 Hz; NCCH2), 154.7 (dd, 3J(C,P) = 3.9 Hz, 3J(C,P) = 0.5 Hz; NCH of C5H4N), 138.6–119.7 (m; aromatic carbon atoms), 50.5 (dd, 3J(C,P) = 3.6 Hz, 3J(C,P) = 2.0 Hz; CH2N), 27.4 (m; PCH2), 26.8 (m; PCH2), 25.2 (s; OCOCH3), 19.5 (dd, 2J(C,P) = 2.4 Hz, 2J(C,P) = 0.5 Hz; PCH2CH2). 31P{1H} NMR (81.0 MHz, CD2Cl2, 20 °C): δ 47.8 (d, 2J(P,P) = 49.1 Hz), 33.1 (d, 2J(P,P) = 49.l Hz).
Method 2
[Ru(κ2-OAc)2(PPh3)2] (200 mg, 0.269 mmol) and dppp (112 mg, 0.272 mmol) were suspended in acetone (2 mL) and stirred for 3 h at room temperature. ampy (40 μL, 0.388 mmol, 1.44 equiv) was added, and the suspension was stirred for 1 h at room temperature. The solid was filtered, washed with n-hexane (3 × 2 mL), and dried under reduced pressure. Yield: 185 mg (93%).
Method 3
trans,cis-[Ru(OAc)2(PPh3)2(ampy)] (2) (100 mg, 0.117 mmol) and dppp (49.5 mg, 0.120 mmol, 1.03 equiv) were stirred in MEK (1 mL) at 50 °C for 20 h. The solution was evaporated under reduced pressure, and the residue was added to n-heptane (5 mL). The suspension was stirred for 10 min at room temperature, and the solid was filtered, washed with n-heptane (2 × 3 mL) and n-pentane (2 × 2 mL), and dried under reduced pressure. Yield: 53 mg (61%).
Synthesis of [Ru(κ2-OAc)(dppp)(ampy)]OAc (8a)
Complex 8 (20 mg, 0.027 mmol) was dissolved in CH3OH (2 mL), and the solution was stirred at room temperature for 56 h. The solvent was evaporated under reduced pressure, and the residue was dissolved in CH2Cl2 (0.5 mL). Addition of n-pentane (2 mL) afforded a yellow-orange precipitate, which was filtered, washed with n-pentane (3 × 2 mL), and dried under reduced pressure. Yield: 18 mg (90%). Anal. Calcd for C37H40N2O4P2Ru (739.75): C, 60.07; H, 5.45; N, 3.79. Found: C, 60.10; H, 5.47; N, 3.81. 1H NMR (400.1 MHz, CD3OD, 20 °C): δ 8.09 (d, 3J(H,H) = 5.7 Hz, 1H; ortho-CH of C5H4N), 7.82 (t, 3J(H,H) = 8.8 Hz, 2H; aromatic protons), 7.76–6.94 (m, 18H; aromatic protons), 6.87 (t, 3J(H,H) = 6.8 Hz, 2H; aromatic protons), 6.80 (t, 3J(H,H) = 8.6 Hz, 1H; aromatic protons), 3.92 (d, 2J(H,H) = 16.9 Hz, 1H; CH2N), 3.29 (d, 2J(H,H) = 16.9 Hz, 1H; CH2N), 3.16–2.77 (m, 4H, PCH2), 2.74–2.35 (m, 2H, CH2), 1.92 (s, 3H; CH3CO2), 1.52 (s, 3H; CH3CO2). 13C{1H} NMR (100.6 MHz, CD3OD, 20 °C): δ 189.6 (d, 2J(C,P) = 2.8 Hz; OCOCH3), 180.4 (br s; OCOCH3), 162.9 (d, 3J(C,P) = 1.4 Hz; NCCH2), 149.9 (br s; NCH of C5H4N), 139.0–122.2 (m; aromatic carbon atoms), 53.5 (d, 3J(C,P) = 3.0 Hz; CH2N), 29.8 (dd, 1J(C,P) = 31.7 Hz, 3J(C,P) = 2.7 Hz; PCH2), 29.6 (dd, 1J(C,P) = 30.3 Hz, 3J(C,P) = 2.7 Hz; PCH2), 24.8 (br s; OCOCH3), 24.4 (s; OCOCH3), 21.9 (t, J(C,P) = 1.9 Hz; CH2). 31P{1H} NMR (162.0 MHz, CD3OD): δ 55.2 (d, 2J(P,P) = 48.4 Hz), 36.7 (d, 2J(P,P) = 48.4 Hz).
Synthesis of trans-[Ru(κ1-OAc)2(dppb)(ampy)] (9)
Method 1
Complex 9 was prepared by following the procedure used for the synthesis of 8 (method 1), with dppb (57.8 mg, 0.136 mmol, 1.01 equiv) in place of dppp. Yield: 62 mg (61%). Anal. Calcd for C38H42N2O4P2Ru (753.78): C, 60.55; H, 5.62; N, 3.72. Found: C, 60.50; H, 5.65; N, 3.70. 1H NMR (200.1 MHz, CD2Cl2, 20 °C): δ 8.95 (m, 1H; ortho-CH of C5H4N), 7.83–7.08 (m, 22H; aromatic protons), 6.81 (pseudo-t, 3J(H,H) = 6.6 Hz, 1H; aromatic proton), 6.03 (m, 2H; NH2), 4.06 (m, 2H; CH2N), 2.78 (m, 2H; PCH2), 2.25 (m, 2H; PCH2), 1.94–1.64 (m, 4H; PCH2CH2CH2), 1.53 (s, 6H; OCOCH3). 13C{1H} NMR (50.3 MHz, CD2Cl2, 20 °C): δ 181.0 (d, 3J(C,P) = 1.5 Hz; OCOCH3), 167.5 (dd, 3J(C,P) = 2.9 Hz, 3J(C,P) = 1.4 Hz; NCCH2), 154.9 (d, J(C,P) = 3.7 Hz; NCH of C5H4N), 139.4–119.9 (m; aromatic carbon atoms), 50.6 (dd, 3J(C,P) = 3.8 Hz, 3J(C,P) = 2.0 Hz; CH2N), 33.9 (dd, 1J(C,P) = 27.1 Hz, 3J(C,P) = 3.0 Hz; PCH2), 27.7 (d, 1J(C,P) = 25.3 Hz; PCH2), 26.5 (m; PCH2CH2), 25.1 (m; OCOCH3), 19.9 (m; PCH2CH2). 31P{1H} NMR (81.0 MHz, CD2Cl2, 20 °C): δ 51.1 (d, 2J(P,P) = 36.6 Hz), 36.5 (d. 2J(P,P) = 36.6 Hz).
Method 2
Complex 9 was prepared by following the procedure used for the synthesis of 8 (method 2), with dppb (115.6 mg, 0.271 mmol, 1.01 equiv) in place of dppp. Yield: 156 mg (77%).
Method 3
Complex 9 was prepared by following the procedure used for the synthesis of 8 (method 3), with dppb (51.2 mg, 0.120 mmol, 1.03 equiv) in place of dppp. Yield: 62 mg (70%).
Synthesis of [Ru(κ2-OAc)(dppb)(ampy)]OAc (9a)
Complex 9a was prepared by following the procedure used for the synthesis of 8a, employing trans-[Ru(κ1-OAc)2(dppb)(ampy)] (9) (20 mg, 0.0265 mmol) in place of 8. The solution of 9 in CH3OH was stirred for 48 h at room temperature. Yield: 19.6 mg (98%). Anal. Calcd for C38H42N2O4P2Ru (753.78): C, 60.55; H, 5.62; N, 3.72. Found: C, 60.60; H, 5.64; N, 3.76. 1H NMR (400.1 MHz, CD3OD, 20 °C): δ 8.26 (d, 3J(H,H) = 5.6 Hz, 1H; ortho-CH of C5H4N), 7.90 (ddd, 3J(H,H) = 9.6 Hz, 3J(H,H) = 7.9 Hz, 4J(H,H) = 1.6 Hz, 2H; aromatic protons), 7.77 (m, 2H; aromatic protons), 7.67 (td, 3J(H,H) = 7.7 Hz, 4J(H,H) = 1.6 Hz, 1H; aromatic proton), 7.63–7.49 (m, 6H, aromatic protons), 7.44–7.25 (m, 5H; aromatic protons), 7.22 (d, 3J(H,H) = 8.0 Hz, 1H; aromatic proton), 7.15 (t, 3J(H,H) = 6.2 Hz, 1H; aromatic proton), 7.06 (m, 1H; aromatic proton), 6.98 (td, 3J(H,H) = 7.9 Hz, 4J(H,H) = 1.6 Hz, 2H; aromatic protons), 6.87 (t, 3J(H,H) = 8.6 Hz, 2H; aromatic protons), 4.03 (d, 2J(H,H) = 16.4 Hz, 1H; CH2N), 3.60 (d, 2J(H,H) = 16.4 Hz, 1H; CH2N), 3.17–2.93 (m, 2H, PCH2), 2.46 (m, 1H; PCH2), 2.30 (m, 1H; PCH2), 2.20–1.99 (m, 2H, CH2), 1.92 (s, 3H; CH3CO2), 1.80 (pseudo-q, J(H,H) = 13.6 Hz, 1H; CH2), 1.73–1.54 (m, 1H; CH2), 1.45 (s, 3H; CH3CO2). 13C{1H} NMR (100.6 MHz, CD3OD, 20 °C): δ 189.7 (t, 2J(C,P) = 2.0 Hz; OCOCH3), 180.5 (s; OCOCH3), 162.0 (d, 3J(C,P) = 1.5 Hz; NCCH2), 150.9 (s; NCH of C5H4N), 140.4–121.5 (m; aromatic carbon atoms), 53.6 (d, 3J(C,P) = 2.9 Hz; CH2N), 31.3 (d, 1J(C,P) = 29.3 Hz; PCH2), 29.4 (pseudo-t, J(C,P) = 27.9 Hz; PCH2), 26.4 (br s; CH2), 24.7 (d; 4J(C,P) = 1.4 Hz; OCOCH3), 24.4 (s; OCOCH3), 23.6 (br s; CH2). 31P{1H} NMR (162.0 MHz, CD3OD, 20 °C): δ 58.2 (d, 2J(P,P) = 37.2 Hz), 46.0 (d, 2J(P,P) = 37.2 Hz).
Synthesis of trans-[Ru(κ1-OAc)2(dppf)(ampy)] (10)
Method 1
Complex 10 was prepared by following the procedure used for the synthesis of 8 (method 1), with dppf (75 mg, 0.135 mmol, 1.01 equiv) in place of dppp. Yield: 87 mg (74%). Anal. Calcd for C44H42FeN2O4P2Ru (881.69): C, 59.94; H, 4.80; N, 3.18. Found: C, 60.00; H, 4.85; N, 3.20. 1H NMR (200.1 MHz, CD2Cl2, 20 °C): δ 8.62 (d, 3J(H,H) = 3.1 Hz, 1H; ortho-CH of C5H4N), 7.81 (t, 3J(H,H) = 7.9 Hz, 3H; aromatic protons), 7.56 (t, 3J(H,H) = 8.8 Hz, 4H; aromatic protons), 7.49–6.92 (m, 15H; aromatic protons), 6.68 (pseudo-t, J(H,H) = 6.3 Hz, 1H; aromatic proton), 6.34 (pseudo-q, J(H,H) = 5.7 Hz, 2H; NH2), 4.68 (br s, 2H; C5H4), 4.32 (br s, 2H; C5H4), 4.15–3.88 (m, 6H; C5H4 and CH2N), 1.55 (s, 6H; OCOCH3). 13C{1H} NMR (50.3 MHz, CD2Cl2, 20 °C): δ 181.2 (d, 3J(C,P) = 1.4 Hz, OCOCH3), 167.7 (dd, 3J(C,P) = 2.9 Hz, 3J(C,P) = 1.6 Hz; NCCH2), 154.6 (d, 3J(C,P) = 3.2 Hz; NCH of C5H4N), 136.6–120.1 (m; aromatic carbon atoms), 82.7 (dd, 1J(C,P) = 43.7 Hz, 3J(C,P) = 4.0 Hz; ipso-C5H4), 81.4 (dd, 1J(C,P) = 47.3 Hz, 3J(C,P) = 2.2 Hz; ipso-C5H4), 75.5 (pseudo-t, J(C,P) = 8.0 Hz; C5H4), 72.9 (d, J(C,P) = 5.6 Hz; C5H4), 70.8 (d, J(C,P) = 4.5 Hz; C5H4), 50.7 (m; CH2N), 25.5 (s; OCOCH3). 31P{1H} NMR (81.0 MHz, CD2Cl2, 20 °C): δ 56.2 (d, 2J(P,P) = 37.8 Hz), 35.0 (d, 2J(P,P) = 37.8 Hz).
Method 2
Complex 10 was prepared by following the procedure used for the synthesis of 8 (method 2), with dppf (149 mg, 0.269 mmol, 1.0 equiv) in place of dppp. Yield: 209 mg (88%).
Method 3
Complex 10 was prepared by following the procedure used for the synthesis of 8 (method 3), with dppf (66.5 mg, 0.120 mmol, 1.03 equiv) in place of dppp. Yield: 75 mg (73%).
Synthesis of [Ru(κ2-OAc)(dppf)(ampy)]OAc (10a)
Complex 10a was prepared by following the procedure used for the synthesis of 8a, employing trans-[Ru(κ1-OAc)2(dppf)(ampy)] (10) (20 mg, 0.0227 mmol) in place of 8. The solution of 10 in CH3OH was stirred for 4 h at room temperature. Yield: 19 mg (95%). Anal. Calcd for C44H42FeN2O4P2Ru (881.69): C, 59.94; H, 4.80; N, 3.18. Found: C, 60.01; H, 4.84; N, 3.16. 1H NMR (400.1 MHz, CD3OD, 20 °C): δ 7.94 (d, 3J(H,H) = 5.7 Hz, 1H; ortho-CH of C5H4N), 7.82 (t, 3J(H,H) = 7.5 Hz, 1H; aromatic proton), 7.70–7.33 (m, 14H, aromatic protons), 7.32–7.23 (m, 4H; aromatic protons), 7.15 (t, 3J(H,H) = 8.8 Hz, 2H; aromatic protons), 7.08 (t, 3J(H,H) = 6.7 Hz, 1H; aromatic proton), 4.55 (s, 1H; C5H4), 4.52 (s, 2H; C5H4), 4.43 (s, 1H; C5H4), 4.41 (s, 2H; C5H4), 4.38 (s, 1H; C5H4), 4.24 (s, 1H; C5H4), 3.91 (d, 2J(H,H) = 16.3 Hz, 1H; CH2N), 3.60 (d, 2J(H,H) = 16.3 Hz, 1H; CH2N), 1.92 (s, 3H; OCOCH3), 1.26 (s, 3H; OCOCH3). 13C{1H} NMR (100.6 MHz, CD3OD, 20 °C): δ 190.8 (t, 2J(C,P) = 2.9 Hz; OCOCH3), 180.4 (s; OCOCH3), 162.4 (d, 3J(C,P) = 1.5 Hz; NCCH2), 151.2 (br s; NCH of C5H4N), 139.2–122.3 (m; aromatic carbon atoms), 80.6 (dd, 1J(C,P) = 55.0 Hz, 3J(C,P) = 3.6 Hz; ipso-C5H4), 78.5 (d, J(C,P) = 11.7 Hz; C5H4), 77.3 (dd, 2J(C,P) = 11.7 Hz, 3J(C,P) = 0.7 Hz; C5H4), 76.3 (dd, 1J(C,P) = 54.5 Hz, 3J(C,P) = 1.3 Hz; ipso-C5H4), 76.0 (d, J(C,P) = 15.3 Hz; C5H4), 75.9 (d, J(C,P) = 15.4 Hz; C5H4), 74.5 (pseudo-t, J(C,P) = 7.3 Hz; C5H4), 74.3 (d, J(C,P) = 7.3 Hz; C5H4), 74.0 (d, J(C,P) = 5.9 Hz; C5H4), 53.1 (d, 3J(C,P) = 2.3 Hz; CH2N), 24.4 (s; OCOCH3), 24.3 (br s; OCOCH3). 31P{1H} NMR (162.0 MHz, CD3OD, 20 °C): δ 59.9 (d, 2J(P,P) = 35.3 Hz), 49.6 (d, 2J(P,P) = 35.3 Hz).
Synthesis of trans-[Ru(κ1-OAc)2((R)-BINAP)(ampy)] (11)
[Ru(κ2-OAc)2(PPh3)2] (100 mg, 0.134 mmol) and (R)-BINAP (85 mg, 0.136 mmol, 1.01 equiv) were suspended in toluene (1.5 mL) and refluxed for 24 h. The resulting orange solution was cooled to room temperature, and ampy (20 μL, 0.194 mmol, 1.45 equiv) was added. The light orange solution obtained was stirred for 1 h at room temperature and the solvent removed under reduced pressure. Treatment of the residue with n-pentane (10 mL) led to a suspension, which was stirred for 10 min, and the yellow precipitate obtained was filtered, washed with n-pentane (3 × 5 mL), and dried under reduced pressure. Yield: 75.1 mg (59%). Anal. Calcd for C54H46N2O4P2Ru (949.99): C, 68.27; H, 4.88; N, 2.95. Found: C, 68.35; H, 4.85; N, 3.01. 1H NMR (400.1 MHz, CD2Cl2, 25 °C): δ 8.48 (m, 1H; ortho-CH of C5H4N), 8.18 (t, 3J(H,H) = 8.1 Hz, 1H; aromatic proton), 7.75–7.69 (m, 2H; aromatic protons), 7.65–7.26 (m, 16H; aromatic protons), 7.25–7.18 (m, 4H; aromatic protons), 7.03–6.91 (m, 2H; aromatic proton and NH2), 6.88 (t, 3J(H,H) = 8.0 Hz, 1H; aromatic proton), 6.84–6.76 (m, 2H; aromatic protons), 6.72 (t, 3J(H,H) = 7.1 Hz, 2H; aromatic protons), 6.62 (t, 3J(H,H) = 6.5 Hz, 1H; aromatic proton), 6.56 (d, 3J(H,H) = 8.6 Hz, 1H; aromatic proton), 6.43 (m, 3H; aromatic protons), 6.26 (d, 3J(H,H) = 8.7 Hz, 1H; aromatic proton), 5.06 (br q, 3J(H,H) = 6.6 Hz, 1H; NH2), 4.07 (dt, 2J(H,H) = 16.0 Hz, 3J(H,H) = 5.6 Hz, 1H; CH2N), 3.97 (m, 1H; CH2N), 1.83 (s, 3H; OCOCH3), 1.61 (s, 3H; OCOCH3). 13C{1H} NMR (100.6 MHz, CD2Cl2, 25 °C): δ 181.8 (d, 3J(C,P) = 1.5 Hz; OCOCH3), 181.3 (d, 3J(C,P) = 1.4 Hz; OCOCH3), 166.9 (dd, 3J(C,P) = 2.7 Hz, 3J(C,P) = 1.1 Hz; NCCH2), 155.5 (d, 3J(C,P) = 3.7 Hz; NCH of C5H4N), 139.0–119.9 (m; aromatic carbon atoms), 50.6 (t, 3J(C,P) = 2.1 Hz; CH2N), 25.8 (br s; OCOCH3), 25.2 (br s; OCOCH3). 31P{1H} NMR (162.0 MHz, CD2Cl2, 25 °C): δ 54.9 (d, 2J(P,P) = 36.9 Hz), 40.9 (d, 2J(P,P) = 36.9 Hz).
Synthesis of [Ru(κ2-OAc)((R)-BINAP)(ampy)]OAc (11a)
Complex 11a was prepared by following the procedure used for the synthesis of 8a, employing trans-[Ru(κ1-OAc)2((R)-BINAP)(ampy)] (11) (22 mg, 0.0232 mmol) in place of 8. The solution of 11 in CH3OH was stirred for 18 h at room temperature. The product consists of a 2:1 molar mixture of two stereoisomers. Yield: 21.1 mg (96%). Anal. Calcd for C54H46N2O4P2Ru (949.99): C, 68.27; H, 4.88; N, 2.95. Found: C, 68.32; H, 4.83; N, 2.99. 1H NMR (400.1 MHz, CD3OD, 25 °C): δ 8.38 (d, 3J(H,H) = 2.9 Hz, 1H; ortho-CH of C5H4N major isomer), 8.21 (d, 3J(H,H) = 3.9 Hz, 1H; ortho-CH of C5H4N minor isomer), 8.09–5.94 (m, 22H; aromatic protons both isomers), 4.39 (d, 2J(H,H) = 16.2 Hz, 1H; CH2N major isomer), 4.16 (d, 2J(H,H) = 16.2 Hz, 1H; CH2N major isomer), 4.08 (d, 2J(H,H) = 16.4 Hz, 1H; CH2N minor isomer), 3.94 (d, 2J(H,H) = 16.4 Hz, 1H; CH2N minor isomer), 1.92 (s, 3H; OCOCH3 minor and major isomers), 1.50 (s, 3H; OCOCH3 major isomer), 1.41 (s, 3H; OCOCH3 minor isomer). 13C{1H} NMR (100.6 MHz, CD3OD, 25 °C): δ 189.3 (d, 2J(C,P) = 2.4 Hz; OCOCH3 major isomer), 189.0 (d, 2J(C,P) = 2.3 Hz; OCOCH3 minor isomer), 180.4 (s; OCOCH3 both isomers), 162.4 (br s; NCCH2 minor isomer), 162.1 (br s; NCCH2 major isomer), 151.7 (br s; NCH of C5H4N minor isomer), 151.2 (br s; NCH of C5H4N major isomer), 143.0–122.2 (m; aromatic carbon atoms both isomers), 53.1 (d, 3J(C,P) = 2.2 Hz; CH2N major isomer), 52.4 (d, 3J(C,P) = 2.4 Hz; CH2N minor isomer), 24.4 (br s; OCOCH3 major isomer), 24.2 (br s; OCOCH3 minor isomer), 23.9 (d; 4J(C,P) = 3.4 Hz; OCOCH3 minor isomer), 23.8 (br s; OCOCH3 major isomer). 31P{1H} NMR (162.0 MHz, CD3OD, 25 °C): δ 68.3 (d, 2J(P,P) = 38.7 Hz; minor isomer), 61.1 (d, 2J(P,P) = 38.8 Hz; major isomer), 58.1 (d, 2J(P,P) = 38.7 Hz; minor isomer), 52.4 (d, 2J(P,P) = 38.8 Hz; major isomer).
Synthesis of trans-[Ru(κ1-OAc)2(dppp)(ampyrim)] (12)
Method 1
Complex 12 was prepared by following the procedure used for the synthesis of 8 (method 1), with ampyrim (18.7 μL, 0.195 mmol, 1.45 equiv) in place of ampy. Yield: 82 mg (82%).
Method 2
trans,cis-[Ru(κ1-OAc)2(PPh3)2(ampyrim)] (3) (100 mg, 0.117 mmol) and dppp (49.5 mg, 0.120 mmol, 1.03 equiv) were stirred in MEK (1 mL) at 50 °C for 18 h. The resulting solution was evaporated under reduced pressure and the residue added to n-heptane (5 mL). The suspension was stirred for 10 min and the solid filtered, washed with n-heptane (2 × 3 mL) and n-pentane (2 × 2 mL), and dried under reduced pressure. Yield: 49 mg (57%). Anal. Calcd for C36H39N3O4P2Ru (740.74): C, 58.37; H, 5.31; N, 5.67. Found: C, 58.35; H, 5.35; N, 5.71. 1H NMR (400.1 MHz, CD2Cl2, 25 °C): δ 8.52 (dd, 3J(H,H) = 4.5 Hz, 4J(H,H) = 1.9 Hz, 1H; RuNCH of C4H3N2), 8.41 (m, 1H; NCH of C4H3N2), 7.66 (t, 3J(H,H) = 8.0 Hz, 4H; aromatic protons), 7.47 (t, 3J(H,H) = 6.8 Hz, 2H; aromatic protons), 7.43–7.30 (m, 8H; aromatic protons), 7.27 (t, 3J(H,H) = 7.1 Hz, 2H; aromatic protons), 7.12 (t, 3J(H,H) = 6.6 Hz, 4H; aromatic protons), 6.74 (t, 3J(H,H) = 5.1 Hz, 1H; aromatic proton), 6,07 (br s, 2H; NH2), 4.28 (td, 3J(H,H) = 6.7 Hz, 4J(H,H) = 2.6 Hz, 2H; CH2N), 2.59–2.44 (m, 4H; PCH2), 2.02–1.85 (m, 2H; CH2), 1.75 (s, 6H; OCOCH3). 13C{1H} NMR (100.6 MHz, CD2Cl2, 25 °C): δ 182.3 (d, 3J(CP) = 2.2 Hz; OCOCH3), 177.8 (dd, 3J(CP) = 2.5 Hz, 3J(CP) = 1.3 Hz; NCCH2), 162.1 (d, 3J(CP) = 3.1 Hz; RuNCH of C4H3N2), 157.4 (s; NCH of C4H3N2), 138.4 (d, 1J(CP) = 41.1 Hz; ipso aromatic carbon atoms), 134.9–128.7 (m; aromatic carbon atoms), 119.8 (t, J(CP) = 1.5 Hz; aromatic carbon atom), 52.0 (t, 3J(CP) = 2.2 Hz; CH2N), 28.1 (dd, 1J(CP) = 30.1 Hz, 3J(CP) = 5.1 Hz; PCH2), 28.0 (d, 1J(CP) = 30.2 Hz; PCH2), 26.4 (s; OCOCH3), 20.7 (d, 2J(CP) = 2.2 Hz; CH2). 31P{1H} NMR (162.0 MHz, CD2Cl2, 25 °C): δ 47.9 (d, 2J(P,P) = 50.1 Hz), 32.6 (d, 2J(P,P) = 50.1 Hz).
Synthesis of [Ru(κ2-OAc)(dppp)(ampyrim)]OAc (12a)
Complex 12a was prepared by following the procedure used for the synthesis of 8a, employing trans-[Ru(κ1-OAc)2(dppp)(ampyrim)] (12) (23 mg, 0.0310 mmol) in place of 8. The solution of 12 in CH3OH was stirred for 64 h at room temperature. Yield: 20 mg (87%). Anal. Calcd for C36H39N3O4P2Ru (740.74): C, 58.37; H, 5.31; N, 5.67. Found: C, 58.32; H, 5.37; N, 5.63. 1H NMR (400.1 MHz, CD3OD, 25 °C): δ 8.93 (dd, 3J(H,H) = 4.8 Hz, 4J(H,H) = 2.9 Hz, 1H; RuNCH of C4H3N2), 8.47 (dd, 3J(H,H) = 4.8 Hz, 4J(H,H) = 1.9 Hz, 1H; NCH of C4H3N2), 7.88 (tt, 3J(H,H) = 8.5 Hz, 4J(H,H) = 1.3 Hz, 3H; aromatic protons), 7.74–7.63 (m, 5H; aromatic protons), 7.56–7.46 (m, 5H; aromatic protons), 7.43–6.97 (m, 7H; aromatic protons), 6.81 (td, 3J(H,H) = 8.2 Hz, 4J(H,H) = 3.9 Hz, 1H; aromatic proton), 4.30 (d, 2J(H,H) = 17.5 Hz, 1H; CH2N), 4.07 (d, 2J(H,H) = 17.5 Hz, 1H; CH2N), 3.12–2.99 (m, 4H; PCH2), 2.61–2.45 (m, 1H; CH2), 2.40–2.22 (m, 1H; CH2), 1.92 (s, 3H; OCOCH3), 1.49 (s, 3H; OCOCH3). 13C{1H} NMR (100.6 MHz, CD3OD, 25 °C): δ 190.3 (d, 2J(C,P) = 2.2 Hz; OCOCH3), 179.8 (br s; OCOCH3), 172.3 (d, 3J(C,P) = 1.4 Hz; NCCH2), 159.5 (s; RuNCH of C4H3N2), 158.0 (br s; NCH of C4H3N2), 137.7–128.8 (m; aromatic carbon atoms), 121.1 (br s; aromatic carbon atom), 53.9 (t, 3J(C,P) = 1.4 Hz; CH2N), 29.4 (dd, 1J(C,P) = 31.3 Hz, 3J(C,P) = 3.1 Hz; PCH2), 28.7 (d, 1J(C,P) = 34.5 Hz; PCH2), 24.5 (d, 4J(C,P) = 1.4 Hz; OCOCH3), 24.0 (br s; OCOCH3), 21.0 (br s; CH2). 31P{1H} NMR (162.0 MHz, CD3OD, 25 °C): δ 56.1 (d, 2J(P,P) = 49.2 Hz), 37.7 (d, 2J(P,P) = 49.2 Hz).
Synthesis of trans-[Ru(κ1-OAc)2(dppb)(ampyrim)] (13)
Method 1
Complex 13 was prepared by following the procedure used for the synthesis of 12 (method 1), with dppb (58.5 mg, 0.137 mmol, 1.02 equiv) in place of dppp. Yield: 78.2 mg (77%).
Method 2
Complex 13 was prepared by following the procedure used for the synthesis of 12 (method 2), with dppb (51.2 mg, 0.120 mmol, 1.03 equiv) in place of dppp. Yield: 66 mg (75%). Anal. Calcd for C37H41N3O4P2Ru (754.77): C, 58.88; H, 5.48; N, 5.57. Found: C, 58.92; H, 5.41; N, 5.51. 1H NMR (400.1 MHz, CD2Cl2, 25 °C): δ 9.00 (dt, 3J(H,H) = 5.8 Hz, 4J(H,H) = 2.9 Hz, 1H; RuNCH of C4H3N2), 8.56 (dd, 3J(H,H) = 4.8 Hz, 4J(H,H) = 2.2 Hz, 1H; NCH of C4H3N2), 7.74–7.66 (m, 4H; aromatic protons), 7.48–7.31 (m, 12H; aromatic protons), 7.23 (ddd, 3J(H,H) = 9.1 Hz, 3J(H,H) = 7.1 Hz, 4J(H,H) = 2.0 Hz, 4H; aromatic protons), 6.84 (t, 3J(H,H) = 5.2 Hz, 1H; aromatic proton), 5.79 (pseudo-q, J(H,H) = 5.4 Hz, 2H; NH2), 4.21 (td, 3J(H,H) = 6.3 Hz, 4J(H,H) = 2.8 Hz, 2H; CH2N), 2.83 (dt, 3J(H,H) = 10.0 Hz, 3J(H,H) = 6.3 Hz, 2H; PCH2), 2.30 (ddd, 3J(H,H) = 11.6 Hz, 3J(H,H) = 6.3 Hz, 4J(H,H) = 3.2 Hz, 2H; PCH2), 1.90–1.78 (m, 2H; CH2), 1.76–1.63 (m, 2H, CH2), 1.61 (s, 6H; OCOCH3). 13C{1H} NMR (100.6 MHz, CD2Cl2, 25 °C): δ 182.3 (d, 3J(CP) = 1.5 Hz; OCOCH3), 178.6 (dd, 3J(CP) = 3.3 Hz, 3J(CP) = 1.4 Hz; NCCH2), 162.5 (d, 3J(CP) = 3.5 Hz; RuNCH of C4H3N2), 157.5 (s; NCH of C4H3N2), 139.4 (d, 1J(CP) = 38.3 Hz; ipso aromatic carbon atoms), 139.0 (d, 1J(CP) = 31.9 Hz; ipso aromatic carbon atoms), 135.3–129.1 (m; aromatic carbon atoms), 119.9 (t, J(CP) = 1.4 Hz; aromatic carbon atom), 52.2 (t, 3J(CP) = 2.2 Hz; CH2N), 34.8 (dd, 1J(CP) = 27.3 Hz, 3J(CP) = 2.6 Hz; PCH2), 28.5 (d, 1J(CP) = 25.0 Hz; PCH2), 27.7 (s; CH2), 26.4 (s; OCOCH3), 21.0 (pseudo-t, J(CP) = 2.8 Hz; CH2). 31P{1H} NMR (162.0 MHz, CD2Cl2, 25 °C): δ 50.0 (d, 2J(P,P) = 37.7 Hz), 36.6 (d, 2J(P,P) = 37.7 Hz).
Synthesis of [Ru(κ2-OAc)(dppb)(ampyrim)]OAc (13a)
Complex 13a was prepared by following the procedure used for the synthesis of 8a, employing trans-[Ru(κ1-OAc)2(dppb)(ampyrim)] (13) (25 mg, 0.0331 mmol) in place of 8. The solution of 13 in CH3OH was stirred for 54 h at room temperature. Yield: 22 mg (88%). Anal. Calcd for C37H41N3O4P2Ru (754.77): C, 58.88; H, 5.48; N, 5.57. Found: C, 58.95; H, 5.44; N, 5.60. 1H NMR (400.1 MHz, CD3OD, 25 °C): δ 8.57 (dd, 3J(H,H) = 3.4 Hz, 4J(H,H) = 1.4 Hz, 1H; RuNCH of C4H3N2), 8.49 (d, 3J(H,H) = 3.7 Hz, 1H; NCH of C4H3N2), 8.00–7.84 (m, 3H; aromatic protons), 7.74 (t, 3J(H,H) = 8.6 Hz, 2H; aromatic protons), 7.67–7.48 (m, 5H; aromatic protons), 7.45–7.26 (m, 4H; aromatic protons), 7.21 (m, 2H; aromatic protons), 7.13–7.00 (m, 2H; aromatic protons), 6.91 (t, 3J(H,H) = 8.2 Hz, 2H; aromatic protons), 6,67 (t, 3J(H,H) = 8.0 Hz, 1H; aromatic proton), 4.09 (d, 2J(H,H) = 16.8 Hz, 1H; CH2N), 3.65 (d, 2J(H,H) = 16.8 Hz, 1H; CH2N), 3.19–3.03 (m, 2H; PCH2), 2.60–2.41 (m, 1H; PCH2), 2.33–2.23 (m, 1H; PCH2), 2.32–2.05 (m, 2H; CH2), 1.95–1.78 (m, 1H, CH2), 1.91 (s, 3H; OCOCH3), 1.64 (m, 1H, CH2), 1.49 (s, 3H; OCOCH3). 13C{1H} NMR (100.6 MHz, CD3OD, 25 °C): δ 190.2 (d, 2J(C,P) = 1.3 Hz; OCOCH3), 180.3 (s; OCOCH3), 172.2 (dd, 3J(C,P) = 3.5 Hz, 3J(C,P) = 1.4 Hz; NCCH2), 158.7 (s; RuNCH of C4H3N2), 158.3 (s; NCH of C4H3N2), 139.9–128.2 (m; aromatic carbon atoms), 122.0 (br s; aromatic carbon atom), 53.9 (d, 3J(C,P) = 1.5 Hz; CH2N), 29.3 (d, 1J(C,P) = 26.3 Hz; PCH2), 29.2 (d, 1J(C,P) = 30.3 Hz; PCH2), 26.6 (t, 3J(C,P) = 1.7 Hz; CH2), 24.8 (d, 4J(C,P) = 1.4 Hz; OCOCH3), 24.3 (br s; OCOCH3), 23.4 (br s; CH2). 31P{1H} NMR (162.0 MHz, CD3OD, 25 °C): δ 57.5 (d, 2J(P,P) = 37.2 Hz), 46.0 (d, 2J(P,P) = 37.2 Hz).
Synthesis of trans-[Ru(κ1-OAc)2(dppf)(ampyrim)] (14)
Method 1
Complex 14 was prepared by following the procedure used for the synthesis of 12 (method 1), with dppf (76.0 mg, 0.137 mmol, 1.02 equiv) in place of dppp. Yield: 101 mg (85%).
Method 2
Complex 14 was prepared by following the procedure used for the synthesis of 12 (method 2), with dppf (66.5 mg, 0.120 mmol, 1.03 equiv) in place of dppp. The solution was heated at 50 °C for 36 h instead of the usual 18 h. Yield: 83 mg (80%). Anal. Calcd for C43H41FeN3O4P2Ru (882.68): C, 58.51; H, 4.68; N, 4.76. Found: C, 58.52; H, 4.71; N, 4.80. 1H NMR (400.1 MHz, CD2Cl2, 25 °C): δ 8.68 (d, 3J(H,H) = 5.8 Hz, 1H; RuNCH of C4H3N2), 8.55 (d, 3J(H,H) = 4.8 Hz, 1H; NCH of C4H3N2), 7.82–7.76 (m, 4H; aromatic protons), 7.62 (t, 3J(H,H) = 8.8 Hz, 4H; aromatic protons), 7.53–7.24 (m, 12H; aromatic protons), 6.74 (t, 3J(H,H) = 5.4 Hz, 1H; aromatic proton), 6.05 (br s, 2H; NH2), 4.80 (br s, 2H; C5H4), 4.38 (s, 2H; C5H4), 4.23–4.09 (m, 4H; C5H4 and CH2N), 4.03 (s, 2H; C5H4), 1.63 (s, 6H; OCOCH3). 13C{1H} NMR (100.6 MHz, CD2Cl2, 25 °C): δ 182.3 (d, 3J(CP) = 1.4 Hz; OCOCH3), 178.9 (dd, 3J(C,P) = 3.8 Hz, 3J(C,P) = 1.4 Hz; NCCH2), 162.2 (d, 3J(CP) = 2.2 Hz; RuNCH of C4H3N2), 157.7 (s; NCH of C4H3N2), 137.2–128.7 (m; aromatic carbon atoms), 119.8 (t, J(C,P) = 1.4 Hz; aromatic carbon atom), 83.4 (dd, 1J(C,P) = 44.4 Hz, 3J(C,P) = 4.0 Hz; ipso-C5H4), 82.3 (dd, 1J(C,P) = 48.4 Hz, 3J(C,P) = 2.2 Hz; ipso-C5H4), 76.8 (d, J(C,P) = 8.1 Hz; C5H4), 76.7 (d, J(C,P) = 8.8 Hz; C5H4), 74.2 (d, J(C,P) = 5.9 Hz; C5H4), 72.2 (d, J(C,P) = 5.1 Hz), 52.3 (t, 3J(CP) = 1.5 Hz; CH2N), 26.8 (s; OCOCH3). 31P{1H} NMR (162.0 MHz, CD2Cl2, 25 °C): δ 55.3 (d, 2J(P,P) = 38.2 Hz), 35.2 (d, 2J(P,P) = 38.2 Hz).
Synthesis of [Ru(κ2-OAc)(dppf)(ampyrim)]OAc (14a)
Complex 14a was prepared by following the procedure used for the synthesis of 8a, employing trans-[Ru(κ1-OAc)2(dppf)(ampyrim)] (14) (23 mg, 0.0261 mmol) in place of 8. The solution of 14 in CH3OH was stirred for 4 h at room temperature. Yield: 22.5 mg (98%). Anal. Calcd for C43H41FeN3O4P2Ru (882.68): C, 58.51; H, 4.68; N, 4.76. Found: C, 58.56; H, 4.73; N, 4.74. 1H NMR (400.1 MHz, CD3OD, 25 °C): δ 8.71 (d, 3J(H,H) = 5.9 Hz, 1H; RuNCH of C4H3N2), 8.09 (d, 3J(H,H) = 4.3 Hz, 1H; NCH of C4H3N2), 7.70–7.57 (m, 6H, aromatic protons), 7.55–7.34 (m, 12H; aromatic protons), 7.32–7.11 (m, 7H; aromatic protons), 4.66 (s, 1H; C5H4), 4.58–4.39 (m, 5H; C5H4), 4.37–4.26 (m, 2H; C5H4), 3.96 (d, 2J(H,H) = 17.2 Hz, 1H; CH2N), 3.51 (d, 2J(H,H) = 17.2 Hz, 1H; CH2N), 1.91 (s, 3H; OCOCH3), 1.31 (s, 3H; OCOCH3). 13C{1H} NMR (100.6 MHz, CD3OD, 25 °C): δ 191.4 (d, 2J(C,P) = 2.1 Hz; OCOCH3), 180.4 (s; OCOCH3), 172.4 (d, 3J(C,P) = 1.5 Hz; NCCH2), 158.9 (s; RuNCH of C4H3N2), 158.0 (s; NCH of C4H3N2), 138.5–129.0 (m; aromatic carbon atoms), 122.4 (d, J(C,P) = 2.2 Hz; aromatic carbon atom), 80.0 (dd, 1J(C,P) = 55.7 Hz, 3J(C,P) = 2.9 Hz; ipso-C5H4), 78.7 (d, J(C,P) = 12.5 Hz; C5H4), 77.3 (d, 2J(C,P) = 9.5 Hz; C5H4), 76.1 (m; C5H4), 75.9 (dd, 1J(C,P) = 52.8 Hz, 3J(C,P) = 2.7 Hz; ipso-C5H4), 75.1 (d, J(C,P) = 7.3 Hz; C5H4), 75.0 (d, J(C,P) = 5.9 Hz; C5H4), 74.0 (d, J(C,P) = 6.6 Hz; C5H4), 73.9 (d, J(C,P) = 5.9 Hz; C5H4), 53.7 (d, 3J(C,P) = 1.5 Hz; CH2N), 24.6 (d, 4J(C,P) = 1.4 Hz; OCOCH3), 24.4 (br s; OCOCH3). 31P{1H} NMR (162.0 MHz, CD3OD, 25 °C): δ 59.8 (d, 2J(P,P) = 35.3 Hz), 47.6 (d, 2J(P,P) = 35.3 Hz).
Synthesis of trans-[Ru(κ1-OAc)2((R)-BINAP)(ampyrim)] (15)
[Ru(κ2-OAc)2(PPh3)2] (100 mg, 0.134 mmol) and (R)-BINAP (85 mg, 0.136 mmol, 1.01 equiv) were suspended in toluene (1.5 mL) and refluxed for 24 h. The resulting orange solution was cooled to room temperature and evaporated to dryness. The residue was dissolved in acetone (2 mL), and ampyrim (18.7 μL, 0.195 mmol, 1.45 equiv) was added. The dark orange solution obtained was stirred for 18 h at room temperature and the solvent removed under reduced pressure. Treatment of the residue with a n-pentane/diethyl ether mixture (3/1; 5 mL) led to a suspension, which was stirred for 10 min. The resulting yellow precipitate was filtered, washed with an n-pentane/diethyl ether mixture (3/1; 4 × 5 mL) and then with n-pentane (2 × 5 mL), and finally dried under reduced pressure. Yield: 80.3 mg (63%). Anal. Calcd for C53H45N3O4P2Ru (950.98): C, 66.94; H, 4.77; N, 4.42. Found: C, 66.98; H, 4.82; N, 4.46. 1H NMR (400.1 MHz, CD2Cl2, 25 °C): δ 8.72 (m, 1H; RuNCH of C4H3N2), 8.46 (m, 1H; NCH of C4H3N2), 8.22 (t, 3J(H,H) = 8.1 Hz, 1H; aromatic proton), 7.70–7.55 (m, 6H; aromatic protons), 7.53–7.44 (m, 4H; aromatic protons), 7.44–7.17 (m, 11H; aromatic protons), 7.06–6.88 (m, 4H; aromatic protons), 6.79 (m, 1H; aromatic proton), 6.71 (t, 3J(H,H) = 6.8 Hz, 1H; aromatic proton), 6.61 (d, 3J(H,H) = 7.2 Hz, 2H; aromatic protons), 6.43 (m, 2H; aromatic protons), 6.24 (d, 3J(H,H) = 8.5 Hz, 1H; aromatic proton), 5.89 (br s, 1H; NH2), 5.34 (br s, 1H; NH2 (overlapped with the solvent signal)), 4.21–4.04 (m, 2H; CH2N), 1.84 (s, 3H; OCOCH3), 1.68 (s, 3H; OCOCH3). 13C{1H} NMR (100.6 MHz, CD2Cl2, 25 °C): δ 182.7 (br s; OCOCH3), 182.6 (s; OCOCH3), 177.9 (d, 3J(C,P) = 3.8 Hz; NCCH2), 163.1 (d, 3J(C,P) = 2.9 Hz; RuNCH of C4H3N2), 157.2 (s; NCH of C4H3N2), 139.7–126.1 (m; aromatic carbon atoms), 119.5 (s; aromatic carbon atom), 52.1 (d, 3J(C,P) = 1.8 Hz; CH2N), 26.9 (s; OCOCH3), 26.5 (s; OCOCH3). 31P{1H} NMR (162.0 MHz, CD2Cl2, 25 °C): δ 53.7 (d, 2J(P,P) = 37.2 Hz), 41.9 (d, 2J(P,P) = 37.2 Hz).
Synthesis of [Ru(κ2-OAc)((R)-BINAP)(ampyrim)]OAc (15a)
Complex 15a was prepared by following the procedure used for the synthesis of 8a, employing trans-[Ru(κ1-OAc)2((R)-BINAP)(ampyrim)] (15) (21 mg, 0.022 mmol) in place of 8. The solution of 15 in CH3OH was stirred for 18 h at room temperature. The product consists of a mixture of two stereoisomers in about a 1:1 ratio. Yield: 18 mg (86%). Anal. Calcd for C53H45N3O4P2Ru (950.98): C, 66.94; H, 4.77; N, 4.42. Found: C, 66.90; H, 4.72; N, 4.37. 1H NMR (400.1 MHz, CD3OD, 25 °C): δ 8.94 (m, 1H; RuNCH of C4H3N2 first isomer), 8.75 (m, 1H; RuNCH of C4H3N2 second isomer), 8.61 (m, 1H; NCH of C4H3N2 first isomer), 8.49 (dd, 3J(H,H) = 4.3 Hz, 4J(H,H) = 1.3 Hz, 1H; NCH of C4H3N2 second isomer), 8.13–5.66 (m, 33H; aromatic protons both isomers), 4.63 (d, 2J(H,H) = 17.0 Hz, 1H; CH2N first isomer), 4.52 (dd, 2J(H,H) = 17.0 Hz, 4J(H,H) = 3.0 Hz, 1H; CH2N first isomer), 4.40 (d, 2J(H,H) = 17.7 Hz, 1H; CH2N second isomer), 4.07 (d, 2J(H,H) = 17.7 Hz, 1H; CH2N second isomer), 1.92 (s, 3H; OCOCH3 both isomers), 1.64 (s, 3H; OCOCH3 second isomer), 1.58 (s, 3H; OCOCH3 first isomer). 13C{1H} NMR (100.6 MHz, CD3OD, 25 °C): δ 190.2 (d, 2J(C,P) = 2.9 Hz; OCOCH3 first isomer), 189.9 (d, 2J(C,P) = 2.3 Hz; OCOCH3 second isomer), 179.8 (br s; OCOCH3 both isomers), 172.8 (br s,; NCCH2 second isomer), 172.4 (br s,; NCCH2 first isomer), 159.3 (s; RuNCH of C4H3N2 second isomer), 159.2 (s; RuNCH of C4H3N2 first isomer), 158.0 (s; NCH of C4H3N2 second isomer), 157.9 (s; NCH of C4H3N2 first isomer), 137.8–126.9 (m; aromatic carbon atoms both isomers), 122.2 (d, J(C,P) = 1.5 Hz; aromatic carbon atom first isomer), 120.2 (s; aromatic carbon atom second isomer), 54.0 (d, 3J(C,P) = 1.5 Hz; CH2N second isomer), 51.4 (d, 3J(C,P) = 2.4 Hz; CH2N first isomer), 24.2 (d; 4J(C,P) = 2.0 Hz; OCOCH3 second isomer), 24.0 (br s; OCOCH3 both isomers), 23.9 (br s; OCOCH3 first isomer). 31P{1H} NMR (162.0 MHz, CD3OD, 25 °C): δ 67.5 (d, 2J(P,P) = 37.2 Hz; first isomer), 59.9 (d, 2J(P,P) = 39.1 Hz; second isomer), 50.8 (d, 2J(P,P) = 37.2 Hz; first isomer), 50.3 (d, 2J(P,P) = 39.1 Hz; second isomer).
Synthesis of trans-[Ru(κ1-OAc)2(dppb)(8-aminoquinoline)] (16)
[Ru(κ2-OAc)2(PPh3)2] (100 mg, 0.134 mmol) and dppb (58 mg, 0.136 mmol, 1.01 equiv) were dissolved in dichloromethane (1.5 mL) and stirred for 1 h at room temperature. 8-Aminoquinoline (28 mg, 0.194 mmol, 1.45 equiv) was added, and the resulting light orange solution was stirred for 1 h at room temperature. The solvent was removed under reduced pressure, and n-pentane (5 mL) was added to the residue, leading to a suspension, which was stirred for 10 min at room temperature. The resulting yellow precipitate was filtered, washed with n-pentane (3 × 5 mL), and dried under reduced pressure. Yield: 95 mg (90%). Anal. Calcd for C41H42N2O4P2Ru (789.81): C, 62.35; H, 5.36; N, 3.55. Found: C, 62.32; H, 5.40; N, 3.53. 1H NMR (400.1 MHz, CD2Cl2, 20 °C): δ 9.23 (t, 3J(H,H) = 4.1 Hz, 1H; NCH of C9H6N), 8.24 (m, 2H; NH2), 8.14 (dd, 3J(H,H) = 8.3 Hz, 4J(H,H) = 1.4 Hz, 1H; aromatic proton), 7.74 (td, 3J(H,H) = 8.5 Hz, 4J(H,H) = 1.5 Hz, 3H; aromatic protons), 7.64 (d, 3J(H,H) = 8.3 Hz, 1H; aromatic proton), 7.52–7.14 (m, 20H; aromatic protons), 7.02 (dd, 3J(H,H) = 8.3 Hz, 3J(H,H) = 5.0 Hz, 1H; aromatic proton), 2.84 (m, 2H; PCH2), 2.26 (pseudo-t, J(H,H) = 7.1 Hz, 2H; PCH2), 2.04–1.52 (m, 4H; CH2), 1.37 (s, 6H; OCOCH3). 13C{1H} NMR (50.3 MHz, CD2Cl2, 20 °C): δ 181.3 (br s; OCOCH3), 156.2 (d, 3J(C,P) = 3.9 Hz; NCH of C9H6N), 150.6–121.3 (m; aromatic carbon atoms), 34.1 (dd, 1J(C,P) = 27.3 Hz, 3J(C,P) = 2.6 Hz; PCH2), 27.8 (d, 1J(C,P) = 24.7 Hz; PCH2), 26.9 (s; PCH2CH2), 25.0 (s; OCOCH3), 19.3 (br s; PCH2CH2). 31P{1H} NMR (81.0 MHz, CD2Cl2, 20 °C): δ 50.5 (d, 2J(P,P) = 36.7 Hz), 37.2 (d, 2J(P,P) = 36.7 Hz).
Synthesis of [Ru(κ2-OPiv)2(PPh3)2] (17)
Compound 17 was prepared by following a procedure different from that previously described.44 [RuCl2(PPh3)3] (1.00 g, 1.043 mmol) and sodium pivalate monohydrate (1.482 g, 10.43 mmol) were suspended in degassed tert-butyl alcohol (20 mL), and the mixture was heated at 70 °C for 2 h until a yellow precipitate was formed. The reaction mixture was cooled to room temperature, and diethyl ether (10 mL) was added. The suspension was stirred at room temperature for 10 min. The precipitate was filtered, washed with water (3 × 10 mL), methanol (2 × 4 mL), and diethyl ether (3 × 5 mL), and finally dried under reduced pressure, giving 17 as a pale orange powder. Yield: 650 mg (75%). Anal. Calcd for C46H48O4P2Ru (827.90): C, 66.74; H, 5.84. Found: C, 66.81; H, 5.86. 1H NMR (200.1 MHz, CDCl3, 20 °C): δ 7.33–7.19 (m, 6H; aromatic protons), 7.18–6.96 (m, 24H; aromatic protons), 0.78 (s, 18H; C(CH3)3). 13C{1H} NMR (50.3 MHz, CDCl3, 20 °C): δ 195.2 (br s; OCOC(CH3)3), 135.6–127.2 (m; aromatic carbon atoms), 39.4 (s; C(CH3)3), 26.6 (br s; C(CH3)3). 31P{1H} NMR (81.0 MHz, CDCl3, 20 °C): δ 64.0 (s).
Synthesis of trans,cis-[Ru(κ1-OPiv)2(PPh3)2(ampy)] (18)
[Ru(κ2-OPiv)2(PPh3)2] (17) (50 mg, 0.0604 mmol) was dissolved in chloroform (1 mL), and ampy (6.5 μL, 0.0631 mmol, 1.04 equiv) was added. The solution was stirred for 10 min at room temperature. Addition of n-pentane (5 mL) afforded an orange precipitate, which was filtered, washed with n-pentane (3 × 2 mL), and dried under reduced pressure. Yield: 48 mg (85%). Anal. Calcd for C52H56N2O4P2Ru (936.05): C, 66.72; H, 6.03; N, 2.99. Found: C, 66.71; H, 6.06; N, 3.03. 1H NMR (200.1 MHz, CDCl3, 20 °C): δ 8.51 (br d, 3J(H,H) = 4.4 Hz, 1H; ortho-CH of C5H4N), 7.60–6.80 (m, 34H; aromatic protons and NH2), 6.55 (pseudo-t, J(H,H) = 6.4 Hz, 1H; aromatic proton), 4.03 (br m, 2H; CH2N), 0.85 (s, 18H; C(CH3)3). 13C{1H} NMR (50.3 MHz, CDCl3, 20 °C): δ 188.2 (d, 3J(C,P) = 1.4 Hz; OCOC(CH3)3), 166.5 (dd, 3J(C,P) = 2.7 Hz, 3J(C,P) = 1.5 Hz; NCCH2), 156.5 (d, 3J(C,P) = 3.8 Hz; NCH of C5H4N), 137.3–118.9 (m; aromatic carbon atoms), 50.9 (t, 3J(C,P) = 2.2 Hz; CH2N), 40.1 (s; C(CH3)3), 28.4 (s; C(CH3)3). 31P{1H} NMR (81.0 MHz, CDCl3, 20 °C): δ 45.8 (d, 2J(P,P) = 31.5 Hz), 38.5 (d, 2J(P,P) = 31.5 Hz).
Synthesis of [Ru(κ1-OAc)(CNNOMe)(PPh3)2] (19)
The ligand HCNNOMe (69.2 mg, 0.323 mmol, 1.2 equiv) and NEt3 (375 μL, 2.690 mmol, 10.0 equiv) were added to [Ru(κ2-OAc)2(PPh3)2] (200 mg, 0.269 mmol) in 2-propanol (2.5 mL), and the mixture was stirred at reflux for 12 h. The dark yellow precipitate was filtered, washed with n-pentane (5 × 3 mL), and dried under reduced pressure. Yield: 181 mg (75%). Anal. Calcd for C51H46N2O3P2Ru (897.96): C, 68.22; H, 5.16; N, 3.12. Found: C, 68.18; H, 5.20; N, 3.10. 1H NMR (400.1 MHz, CD2Cl2, 25 °C): δ 8.86 (m, 1H; NH2), 7.68 (s, 1H; aromatic proton), 7.64–7.04 (m, 24H; aromatic protons), 7.06–6.75 (m, 10H; aromatic protons), 6.59 (d, 3J(H,H) = 6.7 Hz, 1H; aromatic proton), 6.47 (d, 3J(H,H) = 6.0 Hz, 1H; aromatic proton), 4.09 (dd, 2J(H,H) = 17.3 Hz, 3J(H,H) = 6.0 Hz, 1H; CH2N), 3.53 (s, 3H; OCH3), 3.42 (m, 1H; CH2N), 1.92 (m, 1H; NH2), 1.09 (s, 3H; OCOCH3). 13C{1H} NMR (100.6 MHz, CD2Cl2, 25 °C): δ 185.5 (dd, 2J(C,P) = 14.3 Hz, 2J(C,P) = 8.4 Hz; CRu), 180.1 (br s; OCOCH3), 163.4 (s; NCC), 160.1 (s; CCOCH3), 157.3 (s; NCCH2), 142.8–108.6 (m; aromatic carbon atoms), 54.9 (s; CH3O), 51.0 ppm (d, 2J(C,P) = 2.2 Hz; CH2N), 25.1 (d; 4J(C,P) = 2.9 Hz; OCOCH3). 31P{1H} NMR (162.0 MHz, CD2Cl2, 25 °C): δ 57.2 (d, 2J(P,P) = 33.3 Hz), 52.9 (d, 2J(P,P) = 33.3 Hz).
Synthesis of [Ru(κ1-OAc)(AMTP)(dppb)] (20)
Method 1
The ligand HAMTP (22 mg, 0.111 mmol, 1.06 equiv) and NEt3 (150 μL, 1.076 mmol, 10.2 equiv) were added to [Ru(κ2-OAc)2(dppb)] (68 mg, 0.105 mmol) in 2-propanol (1 mL), and the mixture was stirred at reflux for 2 h. The solvent was removed under reduced pressure, and the solid residue was washed with water (1 mL) and dried under reduced pressure for 2–3 days. Yield: 70 mg (85%). Anal. Calcd for C43H44N2O2P2Ru (783.85): C, 65.89; H, 5.66; N, 3.57. Found: C, 65.91; H, 5.60; N, 3.60. 1H NMR (200.1 MHz, toluene-d8, 20 °C): δ 8.65 (br s, 1H; NH2), 8.51 (t, 3J(H,H) = 9.1 Hz, 2H; aromatic protons), 8.06 (s, 1H; aromatic proton), 7.96 (t, 3J(H,H) = 7.6 Hz, 2H; aromatic protons), 7.73–7.05 (m, 12H; aromatic protons), 6.96 (m, 4H; aromatic protons), 6.72 (t, J(H,H) = 7.1 Hz, 2H; aromatic protons), 6.44 (d, 3J(H,H) = 6.0 Hz, 1H; aromatic protons), 6.32 (t, J(H,H) = 7.6 Hz, 2H; aromatic protons), 4.12 (dd, 2J(H,H) = 15.0 Hz, 3J(H,H) = 4.0 Hz, 1H; CH2N), 3.49 (m, 1H; CH2N), 3.40–3.04 (m, 2H; PCH2), 2.35 (s, 3H; CH3), 2.20–1.40 (m, 5H; CH2), 1.92 (s, 3H; CH3CO), 1.22 (m, 1H; NH2), 1.14 (m, 1H; CH2). 31P{1H} NMR (81.0 MHz, CD2Cl2, 20 °C): δ 60.8 (d, 2J(P,P) = 38.3 Hz), 44.6 (d, 2J(P,P) = 38.3 Hz). 31P{1H} NMR (81.0 MHz, toluene-d8, 20 °C): δ 60.7 (d, 2J(P,P) = 38.5 Hz), 44.5 (d, 2J(P,P) = 38.5 Hz).
Method 2
[Ru(κ2-OAc)2(PPh3)2] (100 mg, 0.134 mmol) and dppb (58 mg, 0.136 mmol, 1.01 equiv) were suspended in 2-propanol and refluxed for 1 h. The mixture was cooled to room temperature, and the ligand HAMTP (28 mg, 0.141 mmol, 1.05 equiv) and NEt3 (187 μL, 1.341 mmol, 10 equiv) were added. The mixture was then refluxed for a further 2 h. The solvent was removed under reduced pressure, and the solid residue was washed with water (1.5 mL) and dried under reduced pressure for 2–3 days. Yield: 48 mg (46%).
Synthesis of [Ru(κ1-OAc)(AMBQPh)(dppb)] (21)
Method 1
The ligand HAMBQPh (45.5 mg, 0.160 mmol, 1.03 equiv) and NEt3 (220 μL, 1.578 mmol, 10.2 equiv) were added to [Ru(κ2-OAc)2(dppb)] (100 mg, 0.155 mmol) in 2-propanol (1 mL), and the mixture was stirred at reflux for 3.5 h. The solvent was removed under reduced pressure and the residue added to n-pentane (5 mL). The suspension was stirred for 5 min, and the solid was filtered, washed with n-pentane (2 × 3 mL), and dried under reduced pressure. Yield: 80 mg (59%).
Method 2
[Ru(κ2-OAc)2(PPh3)2] (200 mg, 0.269 mmol) and dppb (115.8 mg, 0.272 mmol, 1.01 equiv) were suspended in 2-propanol (2.5 mL) and refluxed for 4 h. The mixture was cooled to room temperature, and the ligand HAMBQPh (91.8 mg, 0.323 mmol, 1.20 equiv) and NEt3 (375 μL, 2.690 mmol, 10 equiv) were added. The mixture was then refluxed for further 12 h. The obtained suspension was cooled to room temperature and the orange solid was filtered, washed with 2-propanol (2 mL), n-pentane (4 × 5 mL) and dried under reduced pressure. Yield: 152 mg (65%). Anal. Calcd for C50H46N2O2P2Ru (869.95): C, 69.03; H, 5.33; N, 3.22. Found: C, 69.01; H, 5.36; N, 3.23. 1H NMR (200.1 MHz, CD2Cl2, 20 °C): δ 8.61 (m, 1H; NH2), 8.22 (pseudo-t, J(H,H) = 7.6 Hz, 2H; aromatic protons), 7.91 (d, 3J(H,H) = 7.1 Hz, 1H; aromatic proton), 7.80–7.15 (m, 21H; aromatic protons), 7.60 (d, 3J(H,H) = 8.5 Hz, 1H; H-5 benzo[h]quinoline), 6.96 (s, 1H; H-3 benzo[h]quinoline), 6.54 (t, 3J(H,H) = 7.4 Hz, 1H; aromatic proton), 6.22 (t, 3J(H,H) = 6.8 Hz, 2H; aromatic protons), 5.55 (t, 3J(H,H) = 8.4 Hz, 2H; aromatic protons), 4.45 (dd, 2J(H,H) = 16.5 Hz, 3J(H,H) = 5.2 Hz, 1H; CH2N), 3.97 (m, 1H; CH2N), 3.18 (m, 1H; PCH2), 2.86 (m, 1H; PCH2), 2.50 (m, 2H; PCH2), 2.20–1.57 (m, 4H; CH2), 1.33 (s, 3H; OCOCH3), 0.98 (m, 1H; NH2). 13C{1H} NMR (100.6 MHz, CD2Cl2, 25 °C): δ 180.4 (br s; OCOCH3), 180.3 (dd, 2J(C,P) = 16.1 Hz, 2J(C,P) = 8.8 Hz; CRu), 157.5 (s; NCC), 152.7 (br s; NCCH2), 146.6–116.2 (m; aromatic carbon atoms), 52.5 (br s; CH2N), 31.1 (dd, 1J(C,P)= 24.9 Hz, 3J(C,P) = 1.5 Hz; CH2P), 30.7 (d, 1J(C,P) = 32.3 Hz; CH2P), 26.0 (d, 2J(C,P) = 1.5 Hz; CH2CH2P), 25.7 (d; 4J(C,P) = 3.8 Hz; OCOCH3), 22.0 (t, 2J(C,P) = 2.2 Hz; CH2CH2P). 31P{1H} NMR (162.0 MHz, CD2Cl2, 20 °C): δ 59.8 (d, 2J(P,P) = 37.9 Hz), 44.9 (d, 2J(P,P) = 37.9 Hz).
Typical Procedure for TH of Ketones
The ruthenium catalyst solution used for TH was prepared by dissolving the complexes 7–11, 16, and 21 (0.02 mmol) in 2-propanol (5 mL). The catalyst solution (125 μL, 0.5 μmol) and a 0.1 M solution of NaOiPr (200 μL, 20 μmol) in 2-propanol were added subsequently to the carbonyl compound solution (1.0 mmol) in 2-propanol (final volume 10 mL), and the resulting mixture was heated under reflux. The reaction mixture was sampled by removing an aliquot, which was quenched by addition of diethyl ether (1/1 v/v), filtered over a short silica pad, and submitted to GC analysis. The base addition was considered as the start time of the reaction. The S/C molar ratio was 2000:1, whereas the base concentration was 2 mol % with respect to the substrate (0.1 M). The same procedure was followed for TH reactions with other S/C ratios (in the range 2000–10000), using the appropriate amount of catalysts and 2-propanol.
Typical Procedure for HY of Ketones and Aldehydes
The HY reactions were performed in an eight-vessel Endeavor Biotage apparatus. The vessels were charged with the catalysts 7, 9, 10, and 19 (5.0 μmol), loaded with 5 bar of N2, and slowly vented (five times). The carbonyl compounds (5 mmol) and a KOtBu solution (1 mL, 0.1 mmol, 0.1 M) in methanol or ethanol were added. Further addition of the solvent (methanol or ethanol) led to a 2 M carbonyl compound solution. The vessels were purged with N2 and H2 (three times each), and then the system was charged with H2 (20 or 30 bar) and heated to 40 or 50 °C for the required time (16 h). The S/C molar ratio was 1000:1, whereas the base concentration was 2 mol %. A similar method was applied for the reactions with other S/C ratios (in the range 1000–10000), using the appropriate amount of catalysts and solvent. The reaction vessels were then cooled to room temperature, vented, and purged three times with N2. A drop of the reaction mixture was diluted with 1 mL of methanol and analyzed by GC.
Single-Crystal X-ray Crystallographic Structure Determination of Compound 7
Single crystals of complex 7 were obtained by slow cooling of a concentrated solution of the species in CH2Cl2. X-ray diffraction data were collected with a Bruker kappa APEX-II CCD diffractometer equipped with a rotating anode (Bruker AXS, FR591) by using graphite-monochromated Mo Kα radiation (λ = 0.71073 Å). For additional details of the collection and refinement of data, see the Supporting Information.
Acknowledgments
Dedicated to Prof. Christian Bruneau for his outstanding contribution to catalysis. This work was supported by the Ministero dell’Università e della Ricerca (MIUR), PRIN 2015 program no. 20154 × 9ATP_005, the Fellowship Program “Talents for an International House (TALENTS UP)” (seventh R&D FP: PEOPLE-Marie Curie Actions-COFUND), and the AREA Consortium of Trieste for a fellowship for S.G. We thank Mr. Pierluigi Polese for the elemental analyses and Dr. Paolo Martinuzzi for NMR assistance.
Supporting Information Available
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.organomet.1c00059.
NMR data of the isolated complexes and X-ray crystallographic details of compound 7 (PDF)
Accession Codes
CCDC 2058063 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing data_request@ccdc.cam.ac.uk, or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
The authors declare no competing financial interest.
Supplementary Material
References
- a Ngai M.-Y.; Barchuk A.; Krische M. J. Iridium-Catalyzed C-C Bond Forming Hydrogenation: Direct Regioselective Reductive Coupling of Alkyl-Substituted Alkynes to Activated Ketones. J. Am. Chem. Soc. 2007, 129, 280–281. 10.1021/ja0670815. [DOI] [PubMed] [Google Scholar]; b Musashi Y.; Sakaki S. Theoretical Study of Rhodium(III)-Catalyzed Hydrogenation of Carbon Dioxide into Formic Acid. Significant Differences in Reactivity among Rhodium(III), Rhodium(I), and Ruthenium(II) Complexes. J. Am. Chem. Soc. 2002, 124, 7588–7603. 10.1021/ja020063c. [DOI] [PubMed] [Google Scholar]
- Murahashi S.-I.Ruthenium in organic synthesis; Wiley-VCH: Weinheim, Germany, 2004; p 383. [Google Scholar]
- a Salvi L.; Salvini A.; Micoli F.; Bianchini C.; Oberhauser W. Mononuclear ruthenium complexes containing two different phosphines in trans position: II. Catalytic hydrogenation of C = C and C = O bonds. J. Organomet. Chem. 2007, 692, 1442–1450. 10.1016/j.jorganchem.2006.11.036. [DOI] [Google Scholar]; b Ohta T.; Takaya H.; Noyori R. Bis(diarylphosphino)-1,1 binaphthyl (BINAP)-ruthenium(II) dicarboxylate complexes: new, highly efficient catalysts for asymmetric hydrogenations. Inorg. Chem. 1988, 27, 566–569. 10.1021/ic00276a025. [DOI] [Google Scholar]; c Skapski A. C.; Stephens F. A. X-Ray crystal structure of acetatohydridotris(triphenylphosphine)ruthenium(II): a hydrogenation catalyst with a strained octahedral co-ordination. J. Chem. Soc., Dalton Trans. 1974, 390–395. 10.1039/dt9740000390. [DOI] [Google Scholar]; d Mitchell R. W.; Spencer A.; Wilkinson G. Carboxylato-triphenylphosphine complexes of ruthenium, cationic triphenylphosphine complexes derived from them, and their behaviour as homogeneous hydrogenation catalysts for alkenes. J. Chem. Soc., Dalton Trans. 1973, 846–854. 10.1039/dt9730000846. [DOI] [Google Scholar]
- Frediani P.; Bianchi M.; Salvini A.; Guarducci R.; Carluccio L. C.; Piacenti F. Ruthenium carbonyl carboxylate complexes with nitrogen-containing ligands III. Catalytic activity in hydrogenation. J. Organomet. Chem. 1995, 498, 187–197. 10.1016/0022-328X(95)05517-S. [DOI] [Google Scholar]
- a van Buijtenen J.; Meuldijk J.; Vekemans J. A. J. M.; Hulshof L. A.; Kooijman H.; Spek A. L. Dinuclear Ruthenium Complexes Bearing Dicarboxylate and Phosphine Ligands. Acceptorless Catalytic Dehydrogenation of 1-Phenylethanol. Organometallics 2006, 25, 873–881. 10.1021/om050789s. [DOI] [Google Scholar]; b Creswell C. J.; Dobson A.; Moore D. S.; Robinson S. D. Complexes of the Platinum Metals. 17. Molecular Dynamics of the Species [M(O2CR)2(CO)(PPh3)2] (M = Ruthenium, R = Methyl, Trifluoromethyl, Pentafluoroethyl, Pentafluorophenyl; M = Osmium, R = Methyl, Trifluoromethyl). Inorg. Chem. 1979, 18, 2055–2059. 10.1021/ic50198a001. [DOI] [Google Scholar]; c Dobson A.; Robinson S. D. Complexes of the Platinum Metals. 7. Homogeneous Ruthenium and Osmium Catalysts for the Dehydrogenation of Primary and Secondary Alcohols. Inorg. Chem. 1977, 16, 137–142. 10.1021/ic50167a029. [DOI] [Google Scholar]
- Liu P. N.; Su F. H.; Wen T. B.; Sung H. H. Y.; Williams I. D.; Jia G. Selective and Efficient Cycloisomerization of Alkynols Catalyzed by a New Ruthenium Complex with a Tetradentate Nitrogen-Phosphorus Mixed Ligand. Chem. - Eur. J. 2010, 16, 7889–7897. 10.1002/chem.200903441. [DOI] [PubMed] [Google Scholar]
- Arockiam P. B.; Bruneau C.; Dixneuf P. H. Ruthenium(II)-Catalyzed C-H Bond Activation and Functionalization. Chem. Rev. 2012, 112, 5879–5918. 10.1021/cr300153j. [DOI] [PubMed] [Google Scholar]
- a Ackermann L. Carboxylate-Assisted Transition-Metal-Catalyzed C-H Bond Functionalizations: Mechanism and Scope. Chem. Rev. 2011, 111, 1315–1345. 10.1021/cr100412j. [DOI] [PubMed] [Google Scholar]; b Johnson D. G.; Lynam J. M.; Slattery J. M.; Welby C. E. Insights into the intramolecular acetate-mediated formation of ruthenium vinylidene complexes: a ligand-assisted proton shuttle (LAPS) mechanism. Dalton Transactions 2010, 39, 10432–10441. 10.1039/c0dt00431f. [DOI] [PubMed] [Google Scholar]; c Lynam J. M.; Welby C. E.; Whitwood A. C. Exploitation of a Chemically Non-innocent Acetate Ligand in the Synthesis and Reactivity of Ruthenium Vinylidene Complexes. Organometallics 2009, 28, 1320–1328. 10.1021/om800950g. [DOI] [Google Scholar]
- Ackermann L.; Pospech J.; Potukuchi H. K. Well-Defined Ruthenium(II) Carboxylate as Catalyst for Direct C-H/C-O Bond Arylations with Phenols in Water. Org. Lett. 2012, 14, 2146–2149. 10.1021/ol300671y. [DOI] [PubMed] [Google Scholar]
- Miura H.; Terajima S.; Shishido T. Carboxylate-Directed Addition of Aromatic C-H Bond to Aromatic Aldehydes under Ruthenium Catalysis. ACS Catal. 2018, 8, 6246–6254. 10.1021/acscatal.8b00680. [DOI] [Google Scholar]
- Naruto M.; Saito S. Cationic mononuclear ruthenium carboxylates as catalyst prototypes for self-induced hydrogenation of carboxylic acids. Nat. Commun. 2015, 6, 8140. 10.1038/ncomms9140. [DOI] [PMC free article] [PubMed] [Google Scholar]
- BINAP = 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl; dppb = 1,4-bis(diphenylphosphino)butane; DCyPP = 1,3-bis(cyclohexylphosphino)propane; DiPPF = 1,1′-bis(diisopropylphosphino)ferrocene; dppe = 1,2-bis(diphenylphosphino)ethane; dppf = 1,1′-bis(diphenylphosphanyl)ferrocene; dppm = 1,1-bis(diphenylphosphino)methane; dppp = 1,3-bis(diphenylphosphino)propane; Xantphos = 4,5-bis(diphenylphosphanyl)-9,9-dimethylxanthene; ampy = 2-(aminomethyl)pyridine; ampyrim = 2-(aminomethyl)pyrimidine; bipy = 2,2’-bipyridine; en = ethylenediamine; HAMTP = 6-(4-methylphenyl)-2-aminomethylpyridine; HCNNOMe = 6-(4-methoxyphenyl)-2-aminomethylpyridine; HAMBQPh = 4-phenyl-2-aminomethylbenzo[h]quinoline; TsDPEN = N-p-toluenesulfonyl-1,2-diphenylethylenediamine; phen = 1,10-phenanthroline; Piv = pivalate (CHC(CH3)3).
- Ohta T.; Takaya H.; Kitamura M.; Nagai K.; Noyori R. Asymmetric hydrogenation of unsaturated carboxylic acids catalyzed by BINAP-ruthenium(II) complexes. J. Org. Chem. 1987, 52, 3174–3176. 10.1021/jo00390a043. [DOI] [Google Scholar]
- Jeschke J.; Gäbler C.; Korb M.; Rüffer T.; Lang H. Ruthenium Carboxylate Complexes as Efficient Catalysts for the Addition of Carboxylic Acids to Propargylic Alcohols. Eur. J. Inorg. Chem. 2015, 2015, 2939–2947. 10.1002/ejic.201500203. [DOI] [Google Scholar]
- Xie X.; Lu B.; Li W.; Zhang Z. Coordination Determined Chemo- and Enantioselectivities in Asymmetric Hydrogenation of Multi-Functionalized Ketones. Coord. Chem. Rev. 2018, 355, 39–53. 10.1016/j.ccr.2017.07.013. [DOI] [Google Scholar]
- Wang D.; Astruc D. The Golden Age of Transfer Hydrogenation. Chem. Rev. 2015, 115, 6621–6686. 10.1021/acs.chemrev.5b00203. [DOI] [PubMed] [Google Scholar]
- a Haack K.-J.; Hashiguchi S.; Fujii A.; Ikariya T.; Noyori R. The Catalyst Precursor, Catalyst, and Intermediate in the RuII-Promoted Asymmetric Hydrogen Transfer between Alcohols and Ketones. Angew. Chem., Int. Ed. Engl. 1997, 36, 285–288. 10.1002/anie.199702851. [DOI] [Google Scholar]; b Hashiguchi S.; Fujii A.; Haack K. J.; Matsumura K.; Ikariya T.; Noyori R. Kinetic Resolution of Racemic Secondary Alcohols by RuII-Catalyzed Hydrogen Transfer. Angew. Chem., Int. Ed. Engl. 1997, 36, 288–290. 10.1002/anie.199702881. [DOI] [Google Scholar]
- Doucet H.; Ohkuma T.; Murata K.; Yokozawa T.; Kozawa M.; Katayama E.; England A. F.; Ikariya T.; Noyori R. trans-[RuCl2(phosphane)2(1,2-diamine)] and Chiral trans-[RuCl2(diphosphane)(1,2-diamine)]: Shelf-Stable Precatalysts for the Rapid, Productive, and Stereoselective Hydrogenation of Ketones. Angew. Chem., Int. Ed. 1998, 37, 1703–1707. . [DOI] [PubMed] [Google Scholar]
- a Putignano E.; Bossi G.; Rigo P.; Baratta W. MCl2(ampy)(dppf) (M = Ru, Os): Multitasking Catalysts for Carbonyl Compound/Alcohol Interconversion Reactions. Organometallics 2012, 31, 1133–1142. 10.1021/om201189r. [DOI] [Google Scholar]; b Baratta W.; Chelucci G.; Herdtweck E.; Magnolia S.; Siega K.; Rigo P. Highly Diastereoselective Formation of Ruthenium Complexes for Efficient Catalytic Asymmetric Transfer Hydrogenation. Angew. Chem., Int. Ed. 2007, 46, 7651–7654. 10.1002/anie.200702278. [DOI] [PubMed] [Google Scholar]; c Ohkuma T.; Sandoval C. A.; Srinivasan R.; Lin Q.; Wei Y.; Muñiz K.; Noyori R. Asymmetric Hydrogenation of tert-Alkyl Ketones. J. Am. Chem. Soc. 2005, 127, 8288–8289. 10.1021/ja052071+. [DOI] [PubMed] [Google Scholar]; d Baratta W.; Herdtweck E.; Siega K.; Toniutti M.; Rigo P. 2-(Aminomethyl)pyridine-Phosphine Ruthenium(II) Complexes:Novel Highly Active Transfer Hydrogenation Catalysts. Organometallics 2005, 24, 1660–1669. 10.1021/om0491701. [DOI] [Google Scholar]
- a Figliolia R.; Cavigli P.; Comuzzi C.; Del Zotto A.; Lovison D.; Strazzolini P.; Susmel S.; Zuccaccia D.; Ballico M.; Baratta W. CNN pincer ruthenium complexes for efficient transfer hydrogenation of biomass-derived carbonyl compounds. Dalton Transactions 2020, 49, 453–465. 10.1039/C9DT04292J. [DOI] [PubMed] [Google Scholar]; b Facchetti S.; Jurcik V.; Baldino S.; Giboulot S.; Nedden H. G.; Zanotti-Gerosa A.; Blackaby A.; Bryan R.; Boogaard A.; McLaren D. B.; Moya E.; Reynolds S.; Sandham K. S.; Martinuzzi P.; Baratta W. Preparation of Pincer 4-Functionalized 2-Aminomethylbenzo[h]quinoline Ruthenium Catalysts for Ketone Reduction. Organometallics 2016, 35, 277–287. 10.1021/acs.organomet.5b00978. [DOI] [Google Scholar]; c Chelucci G.; Baldino S.; Baratta W. Ruthenium and Osmium Complexes Containing 2-(aminomethyl)pyridine (Ampy)-based Ligands in Catalysis. Coord. Chem. Rev. 2015, 300, 29–85. 10.1016/j.ccr.2015.04.007. [DOI] [Google Scholar]; d Baratta W.; Fanfoni L.; Magnolia S.; Siega K.; Rigo P. Benzo[h]quinoline Pincer Ruthenium and Osmium Catalysts for Hydrogenation of Ketones. Eur. J. Inorg. Chem. 2010, 2010, 1419–1423. 10.1002/ejic.200901253. [DOI] [Google Scholar]; e Baratta W.; Benedetti F.; Del Zotto A.; Fanfoni L.; Felluga F.; Magnolia S.; Putignano E.; Rigo P. Chiral Pincer Ruthenium and Osmium Complexes for the Fast and Efficient Hydrogen Transfer Reduction of Ketones. Organometallics 2010, 29, 3563–3570. 10.1021/om1004918. [DOI] [Google Scholar]; f Baratta W.; Ballico M.; Baldino S.; Chelucci G.; Herdtweck E.; Siega K.; Magnolia S.; Rigo P. New Benzo[h]quinoline-Based Ligands and their Pincer Ru and Os Complexes for Efficient Catalytic Transfer Hydrogenation of Carbonyl Compounds. Chem. - Eur. J. 2008, 14, 9148–9160. 10.1002/chem.200800888. [DOI] [PubMed] [Google Scholar]; g Baratta W.; Siega K.; Rigo P. Fast and Chemoselective Transfer Hydrogenation of Aldehydes Catalyzed by a Terdentate CNN Ruthenium Complex [RuCl(CNN)(dppb)]. Adv. Synth. Catal. 2007, 349, 1633–1636. 10.1002/adsc.200700014. [DOI] [Google Scholar]; h Baratta W.; Bosco M.; Chelucci G.; Del Zotto A.; Siega K.; Toniutti M.; Zangrando E.; Rigo P. Terdentate RuX(CNN)(PP) (X = Cl, H, OR) Complexes: Synthesis, Properties, and Catalytic Activity in Fast Transfer Hydrogenation. Organometallics 2006, 25, 4611–4620. 10.1021/om060408q. [DOI] [Google Scholar]; i Baratta W.; Chelucci G.; Gladiali S.; Siega K.; Toniutti M.; Zanette M.; Zangrando E.; Rigo P. Ruthenium(II) Terdentate CNN Complexes: Superlative Catalysts for the Hydrogen-Transfer Reduction of Ketones by Reversible Insertion of a Carbonyl Group into the Ru-H Bond. Angew. Chem., Int. Ed. 2005, 44, 6214–6219. 10.1002/anie.200502118. [DOI] [PubMed] [Google Scholar]
- Dupau P.; Bonomo L.; Kermorvan L. Unexpected Role of Anionic Ligands in the Ruthenium-Catalyzed Base-Free Selective Hydrogenation of Aldehydes. Angew. Chem., Int. Ed. 2013, 52, 11347–11350. 10.1002/anie.201304912. [DOI] [PubMed] [Google Scholar]
- Giboulot S.; Comuzzi C.; Del Zotto A.; Figliolia R.; Lippe G.; Lovison D.; Strazzolini P.; Susmel S.; Zangrando E.; Zuccaccia D.; Baldino S.; Ballico M.; Baratta W. Preparation of monocarbonyl ruthenium complexes bearing bidentate nitrogen and phosphine ligands and their catalytic activity in carbonyl compound reduction. Dalton Transactions 2019, 48, 12560–12576. 10.1039/C9DT02616A. [DOI] [PubMed] [Google Scholar]
- Hey D. A.; Fischer P. J.; Baratta W.; Kühn F. E. Ru(O2CCF3)2(PPh3)2 and ruthenium phosphine complexes bearing fluoroacetate ligands: synthesis, characterization and catalytic activity. Dalton Transactions 2019, 48, 4625–4635. 10.1039/C9DT00334G. [DOI] [PubMed] [Google Scholar]
- Hey D. A.; Sauer M. J.; Fischer P. J.; Esslinger E.-M. H. J.; Kühn F. E.; Baratta W. Acetate Acetylacetonate Ampy Ruthenium(II) Complexes as Efficient Catalysts for Ketone Transfer Hydrogenation. ChemCatChem 2020, 12, 3537–3544. 10.1002/cctc.202000542. [DOI] [Google Scholar]
- Baratta W.; Ballico M.; Del Zotto A.; Herdtweck E.; Magnolia S.; Peloso R.; Siega K.; Toniutti M.; Zangrando E.; Rigo P. Pincer CNN Ruthenium(II) Complexes with Oxygen-Containing Ligands (O2CR, OAr, OR, OSiR3, O3SCF3): Synthesis, Structure, and Catalytic Activity in Fast Transfer Hydrogenation. Organometallics 2009, 28, 4421–4430. 10.1021/om900274r. [DOI] [Google Scholar]
- a Pardatscher L.; Hofmann B. J.; Fischer P. J.; Hölzl S. M.; Reich R. M.; Kühn F. E.; Baratta W. Highly Efficient Abnormal NHC Ruthenium Catalyst for Oppenauer-Type Oxidation and Transfer Hydrogenation Reactions. ACS Catal. 2019, 9, 11302–11306. 10.1021/acscatal.9b03677. [DOI] [Google Scholar]; b Bitzer M. J.; Pothig A.; Jandl C.; Kuhn F. E.; Baratta W. Ru-Ag and Ru-Au dicarbene complexes from an abnormal carbene ruthenium system. Dalton Transactions 2015, 44, 11686–11689. 10.1039/C5DT01914A. [DOI] [PubMed] [Google Scholar]; c Witt J.; Pöthig A.; Kühn F. E.; Baratta W. Abnormal N-Heterocyclic Carbene-Phosphine Ruthenium(II) Complexes as Active Catalysts for Transfer Hydrogenation. Organometallics 2013, 32, 4042–4045. 10.1021/om400400w. [DOI] [Google Scholar]
- Shahroosvand H.; Nasouti F.; Sousaraei A. Ruthenium(II) multi carboxylic acid complexes: chemistry and application in dye sensitized solar cells. Dalton Transactions 2014, 43, 5158–5167. 10.1039/c3dt52078a. [DOI] [PubMed] [Google Scholar]
- a Honorato J.; Oliveira K. M.; Leite C. M.; Colina-Vegas L.; Nóbrega J. A.; Castellano E. E.; Ellena J.; Correa R. S.; Batista A. A. Half-Sandwich /RuII Anticancer Complexes Containing Triphenylphosphine and p-Substituted Benzoic Acids. J. Braz. Chem. Soc. 2020, 31, 2237–2249. 10.21577/0103-5053.20200076. [DOI] [Google Scholar]; b Pagoto T. M. P.; Sobrinho L. L. G.; Graminha A. E.; Guedes A. P. M.; Carroccia M. C.; de Oliveira P. F.; Silveira-Lacerda E. P.; Deflon V. M.; Tavares D. C.; Pivatto M.; Batista A. A.; Von Poelhsitz G. A ruthenium(II) complex with the propionate ion: Synthesis, characterization and cytotoxic activity. C. R. Chim. 2015, 18, 1313–1319. 10.1016/j.crci.2015.07.008. [DOI] [Google Scholar]
- Lovison D.; Allegri L.; Baldan F.; Ballico M.; Damante G.; Jandl C.; Baratta W. Cationic carboxylate and thioacetate ruthenium(II) complexes: synthesis and cytotoxic activity against anaplastic thyroid cancer cells. Dalton Transactions 2020, 49, 8375–8388. 10.1039/D0DT01390K. [DOI] [PubMed] [Google Scholar]
- a Kamer P. C. J.; van Leeuwen P. W. N. M.. Phosphorus(III) Ligands in Homogeneous Catalysis: Design and Synthesis; Wiley: Chichester, U.K., 2012; Vol. 1, p 547. [Google Scholar]; b Tolman C. A. Steric effects of phosphorus ligands in organometallic chemistry and homogeneous catalysis. Chem. Rev. 1977, 77, 313–348. 10.1021/cr60307a002. [DOI] [Google Scholar]
- Ballico M.; Zuccaccia D.; Figliolia R.; Baratta W. Bulky Diphosphine Acetate Ruthenium Complexes: Synthesis and Catalytic Activity in Ketone Transfer Hydrogenation and Alkyne Dimerization. Organometallics 2020, 39, 3180–3193. 10.1021/acs.organomet.0c00361. [DOI] [Google Scholar]
- Wong W.-K.; Lai K.-K.; Tse M.-S.; Tse M.-C.; Gao J.-X.; Wong W.-T.; Chan S. Reactivity of Ru(OAc)2(Ph3P)2 Toward Chelating Diphosphine Ligands. X-ray Crystal Structures of fac-Ru(OAc)2(Ph3P)(dppm) and trans-Ru(OAc)2(P2N2H4). Polyhedron 1994, 13, 2751–2762. 10.1016/S0277-5387(00)83433-6. [DOI] [Google Scholar]
- Kuznetsov V. F.; Yap G. P. A.; Alper H. Chiral Ruthenium Complexes with P,N-Ligands Derived from (S)-Proline. Organometallics 2001, 20, 1300–1309. 10.1021/om000894w. [DOI] [Google Scholar]
- Ma G.; McDonald R.; Ferguson M.; Cavell R. G.; Patrick B. O.; James B. R.; Hu T. Q. Ruthenium(II) Diphosphine/Diamine/Diimine Complexes and Catalyzed Hydrogen-Transfer to Ketones. Organometallics 2007, 26, 846–854. 10.1021/om060987z. [DOI] [Google Scholar]
- Vijaykumar G.; Mandal S. K. An abnormal N-heterocyclic carbene based nickel complex for catalytic reduction of nitroarenes. Dalton Transactions 2016, 45, 7421–7426. 10.1039/C6DT00470A. [DOI] [PubMed] [Google Scholar]
- a Wiedner E. S.; Chambers M. B.; Pitman C. L.; Bullock R. M.; Miller A. J. M.; Appel A. M. Thermodynamic Hydricity of Transition Metal Hydrides. Chem. Rev. 2016, 116, 8655–8692. 10.1021/acs.chemrev.6b00168. [DOI] [PubMed] [Google Scholar]; b Espinet P.; Albéniz A. C., 1,2-Insertion and n-Elimination. In Current Methods in Inorganic Chemistry; Kurosawa H., Yamamoto A., Eds.; Elsevier: Amsterdam, 2003; Vol. 3, pp 293–371. [Google Scholar]
- a Sandoval C. A.; Ohkuma T.; Muñiz K.; Noyori R. Mechanism of Asymmetric Hydrogenation of Ketones Catalyzed by BINAP/1,2-Diamine-Ruthenium(II) Complexes. J. Am. Chem. Soc. 2003, 125, 13490–13503. 10.1021/ja030272c. [DOI] [PubMed] [Google Scholar]; b Noyori R.; Yamakawa M.; Hashiguchi S. Metal-Ligand Bifunctional Catalysis: A Nonclassical Mechanism for Asymmetric Hydrogen Transfer between Alcohols and Carbonyl Compounds. J. Org. Chem. 2001, 66, 7931–7944. 10.1021/jo010721w. [DOI] [PubMed] [Google Scholar]
- a Baratta W.; Ballico M.; Esposito G.; Rigo P. Role of the NH2 Functionality and Solvent in Terdentate CNN Alkoxide Ruthenium Complexes for the Fast Transfer Hydrogenation of Ketones in 2-Propanol. Chem. - Eur. J. 2008, 14, 5588–5595. 10.1002/chem.200701870. [DOI] [PubMed] [Google Scholar]; b Clapham S. E.; Hadzovic A.; Morris R. H. Mechanisms of the H2-Hydrogenation and Transfer Hydrogenation of Polar Bonds Catalyzed by Ruthenium Hydride Complexes. Coord. Chem. Rev. 2004, 248, 2201–2237. 10.1016/j.ccr.2004.04.007. [DOI] [Google Scholar]; c Petra D. G. I.; Reek J. N. H.; Handgraaf J. W.; Meijer E. J.; Dierkes P.; Kamer P. C. J.; Brussee J.; Schoemaker H. E.; van Leeuwen P. W. N. M. Chiral Induction Effects in Ruthenium(II) Amino Alcohol Catalysed Asymmetric Transfer Hydrogenation of Ketones: An Experimental and Theoretical Approach. Chem. - Eur. J. 2000, 6, 2818–2829. . [DOI] [PubMed] [Google Scholar]
- a Dub P. A.; Gordon J. C. The Mechanism of Enantioselective Ketone Reduction with Noyori and Noyori-Ikariya Bifunctional Catalysts. Dalton Transactions 2016, 45, 6756–6781. 10.1039/C6DT00476H. [DOI] [PubMed] [Google Scholar]; b Dub P. A.; Henson N. J.; Martin R. L.; Gordon J. C. Unravelling the Mechanism of the Asymmetric Hydrogenation of Acetophenone by [RuX2(diphosphine)(1,2-diamine)] Catalysts. J. Am. Chem. Soc. 2014, 136, 3505–3521. 10.1021/ja411374j. [DOI] [PubMed] [Google Scholar]
- Baratta W.; Baldino S.; Calhorda M. J.; Costa P. J.; Esposito G.; Herdtweck E.; Magnolia S.; Mealli C.; Messaoudi A.; Mason S. A.; Veiros L. F. CNN Pincer Ruthenium Catalysts for Hydrogenation and Transfer Hydrogenation of Ketones: Experimental and Computational Studies. Chem. - Eur. J. 2014, 20, 13603–13617. 10.1002/chem.201402229. [DOI] [PubMed] [Google Scholar]
- Relevant NMR data for trans-[RuH(PPh3)2(CNNOMe)] are as follows. 1H NMR (400.1 MHz, iPrOH/toluene-d8, 25 °C): δ −10.01 (t, 2J(H,P) = 26.7 Hz). 31P{1H} NMR (162.0 MHz, iPrOH/toluene-d8, 25 °C): δ 62.2 (s). Relevant NMR data for cis-[RuH(PPh3)2(CNNOMe)] are as follows. 1H NMR (400.1 MHz, iPrOH/toluene-d8, 25 °C): δ −7.30 (dd, 2J(H,P) = 92.4 Hz, 2J(H,P) = 35.5 Hz). 31P{1H} NMR (162.0 MHz, iPrOH/toluene-d8, 25 °C): δ 68.8 (d, 2J(P,P) = 16.5 Hz), 33.9 (d, 2J(P,P) = 16.5 Hz).
- Stephenson T. A.; Wilkinson G. New complexes of ruthenium (II) and (III) with triphenylphosphine, triphenylarsine, trichlorostannate, pyridine and other ligands. J. Inorg. Nucl. Chem. 1966, 28, 945–956. 10.1016/0022-1902(66)80191-4. [DOI] [Google Scholar]
- ampyrim free base was obtained upon treatment of ampyrim·HCl with aqueous KOH until the pH turned basic (litmus paper test) and subsequent extraction with CH2Cl2, filtration of the organic phase over Celite, drying with MgSO4, and further filtration. Dichloromethane was removed by slow evaporation at atmospheric pressure.
- Gilbert J. D.; Wilkinson G. New complexes of ruthenium(II) with triphenylphosphine and other ligands. J. Chem. Soc. A 1969, 1749–1753. 10.1039/j19690001749. [DOI] [Google Scholar]
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