Skip to main content
NCBI home page
ACS AuthorChoice logoLink to ACS AuthorChoice
. 2023 Jun 26;42(13):1649–1657. doi: 10.1021/acs.organomet.3c00190

Synthesis, Structure, and Spectroscopy of the Biscarboranyl Stannylenes (bc)Sn·THF and K2[(bc)Sn]2 (bc = 1,1′(ortho-Biscarborane)) and Dibiscarboranyl Ethene (bc)CH=CH(bc)

Alice C Phung 1, James C Fettinger 1, Philip P Power 1,*
PMCID: PMC10337257  PMID: 37448537

Abstract

graphic file with name om3c00190_0009.jpg

Two compounds containing a Sn(II) atom supported by a bidentate biscarborane ligand have been synthesized via salt metathesis. The synthetic procedures for (bc)Sn·THF (bc = 1,1′ (ortho-carborane) (1) and K2[(bc)Sn]2 (2) involved the reaction of K2[bc] with SnCl2 in either a THF solution (1) or in a benzene/dichloromethane solvent mixture (2). Using the same solvent conditions as those used for 2 but using a shorter reaction time gave a dibiscarboranyl ethene (3). The products were characterized by 1H, 13C, 11B, 119Sn NMR, UV–vis, and IR spectroscopy, and by X-ray crystallography. The diffraction data for 1 and 2 show that the Sn atom has a trigonal pyramid environment and is constrained by the bc ligand in a planar five-membered C4Sn heterocycle. The 119Sn NMR spectrum of 1 displays a triplet of triplets pattern signal, which is unexpected given the absence of a Sn–H signal in the 1H NMR, IR spectrum, and X-ray crystallographic data. However, a comparison with other organotin compounds featuring a Sn atom bonded to carboranes reveal similar multiplets in their 119Sn NMR spectra, likely arising from long-range nuclear spin–spin coupling between the carboranyl 11B and 119Sn nuclei. Compound 3 displays structural and spectroscopic characteristics typical of conjugated alkenes.

Introduction

The charge-neutral compound 1,1′-bis(ortho-carborane) (H2-bc), often described as a three-dimensional aromatic analogue of biphenyl, is an interesting ligand for the support of stannylenes due to its steric bulk and strong κ2-binding that can form strained five-membered metallacycles.1−3 The majority of bc ligand metal complexes feature a transition metal that is κ2-C,C- or κ2-B,C-bonded to the bc ligand and stabilized by an aryl or alkyl group3−11 or another bc ligand.3,12,13 In these cases, the central transition metal is constrained to a square planar or tetrahedral geometry due to the rigid nature of the bc ligand scaffold. Additionally, there are reports of deboronated bc-based transition-metal complexes incorporating the transition-metal atom into the bc cage.3,14−16

In contrast, there are relatively few main group metal complexes stabilized by a bc ligand,17−22 and the synthesis of these complexes has required activation of the C–H vertices of H2-bc. Since the boron-bonded hydrogens are hydridic while the carbon-bonded hydrogens are protic,1,2 lithiation is a common route for the C–H activation of H2-bc. The phosphorus complex closo-(C2B10H10)(PR2)-nido-(C2B10H9) (PHR2) (R = iPr, N(iPr)2, or Ph) describes the activation of H2-bc by lithiation to produce the dilithio salt.18 Alternatively, the synthesis for the 9-borafluorene three-dimensional analogue (bc)B(N(iPr)2) generates the dipotassium salt of bc via potassium bis(trimethylsilyl)amide prior to a salt metathesis reaction with (iPr2)NBCl2.19 Currently, the only known bc complex containing a heavy group 14 metal is the Sn(IV) complex, (bc)SnMe2, synthesized via reaction of the Grignard intermediate (bc)Mg(DME)2 (DME = 1,2-dimethoxyethane) with SnMe2Cl2 (Figure 1).20

Figure 1.

Figure 1

Open in a new tab

Synthetic routes of other bc-supported main-group metal complexes.

Unlike the rarity of bis-carboranyl group 14 complexes, several ortho- and meta-carboranes containing B–Sn and C–Sn bonds are known.23,24 The earliest reports in 1965 concerned the trialkylcarboranyl tin complexes (C2B10H10)(SnR3)2, (R = alkyl), with each carbon vertex of the carborane cage bonded to a Sn(IV) atom, although structural data was not provided.25 The first isolable carboranyl tin structures were the organotin complexes [o-C2B10H10(CH2NMe2)SnR2Br (R = Me or Ph; X = Cl or Br) which feature a Sn(IV) bonded to a carbon vertex and stabilized by a Lewis basic −CH2NMe2 chelating group (Table 2 and ref (26)).26 In general, the majority of the tin-carborane complexes are achieved through an initial lithiation step in the stannylation of the C–H vertices of the carboranes cages.16,23−38

Table 2. 119Sn NMR Chemical Shifts for 1 and Selected Compoundsa.

graphic file with name om3c00190_0008.jpg

Open in a new tab
a

n.r.: not reported.

Monomeric, homoleptic stannylenes of the formula SnR2 are usually supported by bulky organic or related ligands such as alkyl, aryl, silyl, amido, alkoxo, thiolato, etc.39−41 Given the bulkiness and rigidity of H2-bc, the compound may be a suitable platform to support a stannylene, as biscarborane-supported stannylenes are not known prior to this work. Herein, we present the synthesis and characterization of complexes containing a 1,1′-bis(o-carboranyl) stannylene (bc)Sn moiety. These compounds were obtained by first deprotonating H2-bc via potassium bis(trimethylsilyl)amide (KHMDS) to create the potassium salt, K2[bc],9 which was then added to SnCl2 in THF. The reaction of K2[bc] with SnCl2 in a THF solution gives the THF-coordinated (bc)Sn·THF (1), while a benzene/dichloromethane mixture affords K2[(bc)Sn]2 (2). Shortening the reaction tme of the dipotassium salt from 24 h to 9 h prior to addition to a dichloromethane solution of SnCl2 produced the alkene (bc)CH=CH(bc) (3) (Scheme 1), presumably through a coupling reaction between the mono-deprotonated K[H-bc] salt and CH2Cl2 solvent molecules. X-ray crystallography and 1H NMR, 11B NMR, 13C NMR, and UV–vis spectroscopy show that the (bc)Sn moiety in complexes 1 and 2 confer structural and spectroscopic similarities between the two. Compound 1 was further characterized by 119Sn NMR spectroscopy. Characterization by X-ray crystallography, 1H, 11B, 13C NMR, UV–vis, and IR spectroscopy of compound 3 confirms its conjugated alkene structure.

Scheme 1. Syntheses of 1–3.

Scheme 1

Open in a new tab

Experimental Section

General Procedures

All manipulations were carried out by using modified Schlenk techniques under a N2 atmosphere. Solvents were dried over columns of activated alumina using a Grubbs-type purification system (Glass Contour), stored over Na (THF, toluene) mirrors, K (diethyl ether, hexanes) mirrors, or 3 Å molecular sieves (dichloromethane) and degassed via three freeze–pump–thaw cycles prior to use. KHMDS was purchased from Sigma-Aldrich and washed three times with hexanes prior to use. The compound H2-bc was synthesized according to literature procedures.10,42 The 1H, 11B{1H}, 13C{1H}, and 119Sn{1H} NMR spectra were recorded on a Bruker AVANCE DRX 500 MHz spectrometer and the 1H and 13C{1H} spectra were referenced to the residual solvent signals in C6D6 (1H: δ 7.15 ppm, 13C: δ 128.06 ppm).43 UV–visible spectra were recorded using dilute hexane solutions in 3.5 mL quartz cuvettes using an Olis 17 Modernized Cary 14 UV–vis/NIR spectrophotometer. Infrared spectra for 1 and 2 were recorded as Nujol mulls between CsI windows on a PerkinElmer 1430 spectrophotometer. The infrared spectrum for 3 was collected on a Bruker Tensor 27 ATRFTIR spectrometer. Melting points were determined on a Meltemp II apparatus in flame-sealed glass capillaries equipped with a partial immersion thermometer.

(bc)SnTHF (1)

THF (ca. 50 mL) was added to a flask containing H2-bc (0.50 g, 1.75 mmol) and KHMDS (0.69 g, 3.5 mmol) and stirred at room temperature for 1 h. The resulting K2[bc] solution was then added to a room-temperature THF suspension of SnCl2 (0.33 g, 1.75 mmol). The solution was stirred overnight to afford a pale pink solution. The THF was removed under reduced pressure, and the resulting dark pink solid was re-dissolved in ca. 40 mL of warm toluene. Filtration through a Celite plug gave a pale-yellow solution. The toluene was removed under reduced pressure, and the solid was re-dissolved in dichloromethane. Concentration of the dichloromethane solution to ca. 10 mL and storage at ca. −18 °C gave pale yellow crystals of 1. Yield: 0.57 g (70%). mp 250–260 °C. 1H NMR (500 MHz, C6D6, 20 °C): δ 1.40 (m, 4H, THF CH2(3,4)) δ 1.41–3.40 (m, BH), and δ 3.55 (m, 4H, THF CH2(2,5)). 11B{1H} NMR (160.5 MHz, C6D6, 20 °C) δ −11.47 (5B), δ −9.33 (6B), δ −8.12 (5B), δ 1.27 (2B), and δ 0.59 (2B). 13C{1H} NMR (151 MHz, C6D6, 20 °C): δ 24.95 (THF CH2(3,4), δ 62.91 (bcC) δ 69.99 (THF CH2(2,5)), and δ 71.81 (bcC). 119Sn NMR (149 MHz, C6D6, 20 °C): δ −137.31 (2J119Sn–11B = 1487 Hz). UV–Vis (toluene): λmax (ε) 280 nm (15,000 mol–1 L cm–1) 345 nm (9600 mol–1 L cm–1).

K2[(bc)Sn]2 (2)

Benzene (ca. 50 mL) was added to a flask containing H2-bc (0.50 g, 1.75 mmol) and KHMDS (0.69 g, 3.5 mmol) and stirred at room temperature until a tan-colored solution was achieved (approx. 24–48 h). The K2[bc] solution was then added directly to a room-temperature dichloromethane solution of SnCl2 (0.33 g, 1.75 mmol). The solution was stirred overnight to yield a pale pink solution. The solvent was removed under reduced pressure, and the orange solid was re-dissolved in warm toluene and separated from the light gray solid by filtration. Toluene was removed under reduced pressure, and the solid was re-dissolved in dichloromethane. Pale yellow crystals of 2 were grown from a concentrated dichloromethane solution (ca. 10 mL) stored at room temperature overnight. Yield: 0.39 g (50%). mp 240 °C. 1H NMR (600 MHz, C6D6, 20 °C): δ 1.50–3.50 (m, BH). 11B{1H} NMR (160.5 MHz, C6D6, 20 °C) δ −11.47 (5B) δ −9.33 (6B), δ −8.12 (5B), δ 1.27 (2B), and δ 0.59 (2B). 13C{1H} NMR (151 MHz, C6D6, 20 °C): δ 62.91 (bcC), and δ 71.62 (bc C). 119Sn NMR signal not observed. UV–vis (toluene): λmax (ε) 280 nm (3700 mol–1 L cm–1) 345 nm (820 mol–1 L cm–1).

(bc)2(CH)2 (3)

Benzene (ca. 50 mL) was added to a flask containing H2-bc (0.50 g, 1.75 mmol) and KHMDS (0.69 g, 3.5 mmol) and stirred at room temperature for 9–12 h. The pale-yellow slurry was then added directly to a room-temperature dichloromethane solution of SnCl2 (0.33 g, 1.75 mmol). The solution was stirred overnight until all SnCl2 solids were solubilized, affording a pale yellow-orange solution. The solvent was removed under reduced pressure, and the orange solid was re-dissolved in warm toluene to filter off the white solid. Toluene was removed under reduced pressure, and the product was re-dissolved in ca. 10 mL of benzene. Concentration of the benzene solution of the product to ca. 1 mL and storage overnight at room temperature gave yellow-orange crystals of 3. Yield: 0.27 g (50%). mp 260–270 °C. 1H NMR (500 MHz, C6D6, 20 °C): δ 1.40–3.50 (m, BH), δ 3.78 (s, 2H, cage CH), δ 5.44 (s, 1H, olefinic CH), and δ 6.10 (s, 1H, C=CH). 11B{1H} NMR (160.5 MHz, C6D6, 20 °C) δ −11.47 (8B), δ −9.33 (11B), δ −8.04 (9B), δ −6.37 (2B), δ 1.27 (5B), and δ 0.56 (5B). 13C{1H} NMR (151 MHz, C6D6, 20 °C): δ 2.65 (olefinic CH), δ 62.91 (bcC), and δ 71.82 (bc C). UV–vis (toluene): λmax (ε) 284 nm (780 mol–1 L cm–1), 334 nm (290 mol–1 cm–1). AT-FTIR: ν=CH 3063 (s), ν=CH 1254.13 (s), ν=CH 1069.56 (s), ν=CH 716.55 (s).

Results and Discussion

Synthesis

C–H activation in organometallic species often involves their treatment with alkyl lithium reagents to create a reactive C–Li bond. Working with the biscarborane system presents an interesting synthetic challenge, as both the hydridic B–H and protic C–H vertices of H2-bc are potentially susceptible to lithiation,44,45 with the lack of selectivity previously noted to lead to isomers10 or cage-opened products.17,18,46 Peryshkov and co-workers in 2016 had intended to synthesize an “independently C-substituted biscarborane cluster” and bind a phosphorus atom to the bc ligand through the carbon vertices in κ1-mode.18 However, addition of a dialkylphosphine chloride to the Li2[bc]/THF solution gave an asymmetric scaffold, with one of the carborane cages of the bc molecule undergoing a cage-opening reaction to produce the closo-(C2B10H10)-nido-(C2B10H9) backbone.18Nido-carboranyl species are a known decomposition product of H2-bc in the presence of a strong base or nucleophile.44,47−49

Synthetic methods for selective bc vertex-activation were first reported in 2018 with the (bc)Pt(dtb-bpy) (dtb-bpy = 4,4′-di-tert-butyl-2,2′-bipyridine) isomers.9 The κ2-C,C-bound isomer was generated by reacting H2-bc with 2 equiv of the non-nucleophilic and mild base potassium bis(trimethylsilyl)amide (KHMDS) and the κ2-B,C-bound isomer was generated by reacting H2-bc stepwise with 1 equiv of KHMDS and 1 equiv of MeLi.9 This method of selectively activating the C–H vertices without forming deboronated nido-carboranyl side products via a non-nucleophilic, mild base was utilized to generate compounds 1–3.

Initially, following the procedure of Spokoyny and coworkers9 produced a tan-colored THF solution of K2[bc] which was added to a THF suspension of 1 equiv of SnCl2 and resulted in the isolation of compound 1. Recrystallization from dichloromethane gave pale yellow crystals of 1. X-ray crystallographic data revealed a THF molecule bound to the central Sn atom in addition to the bc ligand.

The synthesis of 2 proceeded similarly to that of 1 but with the difference that the THF solvent was replaced with a benzene/dichloromethane mixture (Scheme 1). Generating K2[bc] in a benzene solution required increased time due to the low solubility of the dipotassium salt in benzene in comparison to that in THF. Once a benzene solution assumed the same tan color as the K2[bc]/THF solution, approx. 24–48 h at room temperature, addition to a rapidly stirring dichloromethane solution of 1 equiv of SnCl2 gave, after workup and recrystallization in the same manner as 1, light orange crystals of 2.

Compound 3 was synthesized by a procedure similar to that of 2, with the only difference being the amount of time the benzene solution was allowed to stir (Scheme 1). Stirring 1 equiv of H2-bc with 2 equiv of KHMDS in benzene for approx. 9–12 h afforded an ivory-colored to pale-yellow solution which was then added to a rapidly stirring dichloromethane solution of 1 equiv of SnCl2. Workup and recrystallization from benzene gave pale-orange crystals of 3. The additional carbon atoms to afford the C=C bridging fragment are from the dichloromethane solvent. Given the pale color of the K2[bc] benzene solution observed with the shortened reaction time, it is likely that the KHMDS had activated only one C–H vertex prior to addition to the SnCl2/CH2Cl2 solution. This mono-activated K[H-bc] proceeded to react with the solvent molecules to afford a C=C bond. The reaction was repeated without SnCl2, but compound 3 was not generated, suggesting that SnCl2 is required to create the bridging alkene, possibly via a coupling mechanism similar to the Stille reaction.50

X-ray Crystal Structures

Due to the rigid nature of the bc ligand, the stannylenes in 1 and 2 are constrained to a five-membered C4Sn cycle. The sum of the angles of the stannocycles equal 533.45° in 1 and 538.55 and 538.96° in 2, indicating an essentially planar C4Sn cyclic moiety. The C–C bond that links the carborane cages together in 1 and 2 is in the range 1.532(5)–1.542(4) Å, which is slightly shorter than the C–C bond in the H2-bc precursor (1.602(2)).51 Additionally, the Sn–C bonds of 1 and 2 are 2.272(3)–2.309(3) Å (Table 1), slightly longer than the sum of the covalent radii of Sn (1.40 Å) and C (0.75 Å).52 The shortened Ccage–Ccage bond and the minor elongation of the Sn–C single bond likely function to relieve strain to accommodate the larger Sn atom into the planar heterocycle. This constrained framework has also forced a narrow sub-90° angle at the central Sn atom at 83.05(12)° in 1 and 81.69 and 81.86° in 2 (Table 1), enabling a C–Sn–C bond angle narrower than other 5-membered organotin heterocycles (82.9(9)–93.8(2)°).53−64

Table 1. Selected Structural Data for 1–3.

compound 1 2 3
Ccage–Sn, Å 2.272(3), 2.279(4) Sn1: 2.276(3), 2.309(3)  
    Sn2: 2.288(4), 2.289(3)  
Sn–O or Sn–K, Å 2.249(3) Sn1: 2.5876(8)  
    Sn2: 2.5855(9)  
Ccage–Sn–Ccage, deg 83.05(12) Sn1: 81.69(11)  
    Sn2: 81.86(12)  
C–Sn–THF or C–Sn–K, deg 90.95(12), 93.12(12) Sn1: 88.23(10), 94.11(7)  
    Sn2: 92.68(7), 90.89(7)  
C=C, Å     1.319(4)
Ccage–Colefin, Å     1.488(3)
Ccage–Colefin–Colefin, deg     123.1(1)
Open in a new tab

Compound 1 co-crystallizes with two dichloromethane molecules and shows that a THF molecule is coordinated to the κ2-C,C-bonded Sn atom. The Sn–OTHF distance of 2.239(3) Å is within the range of other Sn–OTHF distances in THF-coordinated Sn(II) complexes (2.261(14)–2.422(6) Å),65−68 consistent with a dative Sn ← O interaction. Additionally, the THF molecule is bonded to the Sn atom at approximately perpendicular to the C4Sn plane, with C–Sn-OTHF angles at 90.95(12) and 93.12(12)° (Figure 2b). In total, the sum of the angles around the tin atom equals 267.12(12)° and indicates a highly pyramidalized geometry. The coordination geometry at Sn is typical of other THF-coordinated Sn complexes, which report C–Sn–OTHF angles in the range 84.8(3)–94.6(6)°.65−68

Figure 2.

Figure 2

Open in a new tab

Thermal ellipsoid plot (50%) of 1. CH2Cl2 solvent molecules are not shown for clarity. (a) “Top” view of 2. (b) “Side” view of 2. Selected bond lengths (Å) and angles (deg): C1–Sn1 = 2.272(3), C4–Sn1 = 2.279(4), O1–Sn1 = 2.249(3), C1–Sn1–C4 = 83.05(12), C1–Sn1–O1 = 90.95(12), C4–Sn1–O1 = 93.12(12).

Compound 2 co-crystallizes with two dichloromethane molecules as well as two K+ ions from K2[bc] in the first step in the synthesis. One K+ ion forms a Sn–K–Sn bridging fragment between two (bc)Sn moieties (Figure 3a), and the other K+ ion appears as a counterion coordinated to the B–H vertices of the bc cage (Figure 3b). Compound 2 is unusual in that the Sn–K distances at 2.5866(8) and 2.5855(9) Å are significantly shorter than the Sn–K distances of low-valent Sn(II) and Sn(I) complexes containing a K+ counterion, which report values within the range 3.460(4)–3.7202(1) Å.69−72 The short Sn–K distances in 2 indicates a strong interaction between the two atoms, though whether this arises from the rigid sterics or electron-withdrawing influence of the bc ligands cannot be determined. The counteranion charge should be delocalized over the biscarborane cages.1,3

Figure 3.

Figure 3

Open in a new tab

Thermal ellipsoid plot (50%) of 2. (a) “Top” view of 2 to show coordination of K1. CH2Cl2 solvent molecules are not shown for clarity. (b) Expanded view of 2 to show coordination of K2. (c) “Side” view of 2 to show coordination of K1. CH2Cl2 solvent molecules are not shown for clarity. Selected bond lengths (Å) and angles (deg): C1–Sn1 = 2.276(3), C4–Sn1 = 2.309(3), C5–Sn2 = 2.288(4), C8–Sn2 = 2.289(3), K1–Sn1 = 2.5876(8), K1–Sn2 = 2.5855(9), C1–Sn1–C4 = 81.69(11), C5–Sn2–C8 = 81.86(12), C1–Sn1–K1 = 88.23(10), C4–Sn1–K1 = 94.11(7), C5–Sn2–K1 = 92.68(7), C8–Sn2–K1 = 90.89(7).

Structural data for compound 3 shows an inversion center which imposes a trans configuration around the central C1–C1′ bond (Figure 4). The C1–C1′ bond distance (1.319(4) Å) and C2–C1–C1′ bond angle (123.1(2)°) are consistent with the presence of a C=C double bond.67 Overall, compound 3 has C2h symmetry. A series of dicarboranyl ethenes R(C2B10H10)CH=CH(C2B10H10)R (R = Ph or C6H4Me-p) analogous to compound 3 similarly contain a trans C=C double bond.46 More recently, carborane clusters linked via a phenyl group have also been reported, generally containing the formula (C2B10H11)–Ph–(C2B10H11).73−75 To the best of our knowledge, compound 3 is the first dibiscarboranyl ethene in the literature.

Figure 4.

Figure 4

Open in a new tab

Thermal ellipsoid plot (50%) of 3. Cage-bonded H atoms are not shown for clarity. Selected bond lengths (Å) and angles (deg): C1–C1′ = 1.319(4), C1–C2 = 1.488(3), C3–C4 = 1.533(3), C2–C1–C1′ = 123.1(2).

Spectroscopy

Compounds 1-3 were characterized by 1H NMR, 11B NMR, 13C NMR, UV–vis, and IR spectroscopy. Compound 1 was also characterized by 119Sn NMR spectroscopy.

The 1H NMR spectrum for 1 displays the coordinated THF proton signals at 1.40 and 3.55 ppm, which is in the same range as those of other THF-coordinated Sn(II) complexes (δCH2(3,4) = 1.3–1.8; δCH2(2,5) = 3.5–3.7)65−68 as well as signals due to free THF in C6D6 (δCH2(3,4) = 1.43; δCH2(2,5) = 3.57).43

The 119Sn NMR spectrum for 1 displays a signal at −137.31 ppm. Related (bc)Sn compounds have 119Sn signals further downfield than compound 1, with (bc)SnMe2 having a signal at −21.22 ppm in d8-THF and the methyl-substituted derivative (Mebc)SnMe2 (Mebc = 8,8′,9,9′,10,10′,12,12′-octamethyl-1,1′-bis(o-carborane)) at 9.20 ppm in d8-THF and 53.10 ppm in C6D6 (Table 2).20 A decrease in the coordination environment around the Sn atom usually results in a downfield shift of the 119Sn resonance.76 Nonetheless, 3-coordinate 1 displays an upfield shift in comparison to the 4-coordinate (bc)SnMe2 and (Mebc)SnMe2. The three-coordinate, THF-bonded complexes Sn[OC(C4H3S)3]2(THF)65 and [Sn(box)(THF)]+ (box = 1,1-bis[(4S)-4-phenyl-1,3-oxazolin-2-yl]ethane)67 report 119Sn NMR signals upfield of the chemical shifts of 1 at −244.5 and −377.1 ppm, respectively. As the signal for 1 is observed between its tetra-coordinated analogues and Sn(II) ← THF derivatives, THF coordination aids in shielding the tin atom, leading to a more shielded Sn atom than that in (bc)SnMe2 and (Mebc)SnMe2, while the electron-withdrawing effect of the bc ligand causes a deshielding on Sn relative to other Sn(II) ← THF complexes.

The triplet of triplets which occurs in the 119Sn NMR spectrum of compound 1 is unusual, given the absence of a Sn–H signal in its 1H NMR and IR spectra and X-ray structural data. Additionally, 119Sn NMR signals for Sn(II) ← THF complexes often appear as singlets in the spectrum (Table 2).65−67 However, multivalent Sn complexes bonded to electron-withdrawing groups and supported by a Sn ← X (X = N or P) dative bond report multiplets in their 119Sn NMR spectra (Table 2).26−28,66 The carboranyl–tin complexes by Gielen and coworkers report 1:2:3:4:3:2:1 septets in their corresponding 119Sn NMR spectra at −166.3 and −166.2 ppm, with coupling constants of 1268 and 1271 Hz28 similar to the coupling constant for the 119Sn NMR signal of 1 (1487 Hz). In addition, carboranyl tin complexes supported by a Sn ← X dative bond (X = N or P) typically observe doublets in the 119Sn NMR spectrum, depending on both the identity of the X atom and coordination about Sn.26−28,30,76−78 The splitting patterns which appear in the 119Sn NMR spectra of compound 1 and carboranyl tin coordination complexes presumably arise from long-range nuclear spin–spin coupling between the carboranyl boron and tin nuclei.79,80 The quadrupolar relaxation rate of the 11B nucleus (I = 3/2) is known to influence the appearance of the resonances of nuclei with spin I = 1/2, such as 119Sn.79−81 Specific to compound 1, the four boron atoms bonded to the tin-bound carbon atom (B3, B6, B7, and B11) exist in two different chemical environments due to the C2v symmetry of the o-carborane cage (Figure 5), likely causing the triplet of triplets displayed in the 119Sn spectrum of 1.

Figure 5.

Figure 5

Open in a new tab

Left: Tin-bonded carbon vertex face is marked with a blue circle. Right: “Front” view of the blue-circled face, showing the two chemical environments of B3/B6 (italicized) vs B7/B11.

Despite numerous attempts to record spectra, with the use of a wide variety of parameters, the 119Sn NMR signal for compound 2 could not be detected. Problems in obtaining the 119Sn data were also encountered for the dianions K2[AriPr6SnSnAriPr6], which was hypothesized to be caused by the unsymmetric electron environment at the Sn atoms, which may cause rapid relaxation through the high anisotropy of the chemical shift tensor.70,82 The THF ligand in 1 appears to stabilize the electron environment at the Sn atom to facilitate detection of a signal. In addition, though the 11B NMR spectra of 1 and 2 are both proton-decoupled, the spectrum for 2 displays tin satellites at −14 and −5 ppm (See Supporting Information, Figure S5) that are absent in the spectrum for 1. This difference can also be attributed to the coordination of THF to the 119Sn nucleus in 1 but not 2.

The UV–vis spectrum of 1 displays two absorptions in the near-UV region at 280 and 345 nm. These absorptions persist in 2, appearing also at 280 and 345 nm regardless of whether a THF or K ion is coordinated to Sn. The similar absorptions in the UV–vis spectra for 1 and 2 suggests that compounds 1 and 2 exist as the same compound in the solution phase. The relatively intense absorptions at 280 nm and similarly at 284 nm in the UV–vis spectrum for 3 can be tentatively assigned to an energy transfer on the bis-carborane ligand. The near-UV vis region of the absorption bands of 1 and 2 suggests a high-energy HOMO → LUMO transition of the (bc)Sn compounds.

Compound 3 exhibits spectroscopic features characteristic of alkenes. The olefin protons appear at 5.43 and 6.10 ppm in the 1H NMR spectrum and the olefin carbon at 2.65 ppm in the 13C NMR spectrum at the high frequency shifts indicative of more conjugated alkenes.83 The UV–vis spectrum of 3 displays a shoulder at 334 nm, corresponding to an olefin π → π* transition at a relatively longer wavelength for alkenes groups, further confirming a conjugated alkene.83 Interestingly, a νC=C stretching frequency in the IR spectrum within the characteristic 1680–1640 cm–1 region is not observed.

Conclusions

The syntheses for 1–3 proceeded in a similar way to each other with only simple modifications in solvents or reaction time. In THF solvent, the synthetic procedure gave the THF-coordinated 1, while using a stepwise benzene and dichloromethane solvent mixture gave 2. Shortening the reaction period of the step that generates the dipotassium salt from 24–48 h to 9–12 h gave the alkene 3. Compound 1 exists as a Lewis acid–base pair with THF, as displayed in the X-ray structural data. Furthermore, the bc ligand platform confers interesting spectroscopic characteristics in the 119Sn NMR spectrum that is unusual for Sn(II)–THF complexes but usual for organotin complexes featuring electron-withdrawing ligands like carboranes. X-ray structural data for 2 show that the Sn atom contains a similar structural motif to that of 1. Compound 3 is the first example of a dibiscarborane-supported alkene.

Acknowledgments

We thank the Office of Basic Energy Sciences, U.S. Department of Energy (DE-PB02-07ER4675) for financial support and the X-ray diffractometer (NSF Grant 0840444). A.C.P. would like to thank Dr. Kent Kirlokovali and Dr. Rafal Dziedzic for useful comments and Dr. Alexander Spokoyny for his continued interest and mentorship.

Supporting Information Available

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.organomet.3c00190.

  • Crystallographic data and NMR, IR, and UV–vis spectra (PDF)

Author Contributions

The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript.

The authors declare no competing financial interest.

Supplementary Material

om3c00190_si_001.pdf (1MB, pdf)

References

  1. Grimes R. N.Carboranes; Elsevier, 2016. [Google Scholar]
  2. Grimes R. N. Carboranes in the Chemist’s Toolbox. Dalton Trans. 2015, 44, 5939–5956. 10.1039/c5dt00231a. [DOI] [PubMed] [Google Scholar]
  3. Welch A. J.Bis(Carboranes) and Their Derivatives. 50th Anniversary of Electron Counting Paradigms for Polyhedral Molecules, 2021; pp 163–195.
  4. Jeans R. J.; Chan A. P. Y.; Riley L. E.; Taylor J.; Rosair G. M.; Welch A. J.; Sivaev I. B. Arene–Ruthenium Complexes of 1,1′-Bis(Ortho-Carborane): Synthesis, Characterization, and Catalysis. Inorg. Chem. 2019, 58, 11751–11761. 10.1021/acs.inorgchem.9b01774. [DOI] [PubMed] [Google Scholar]
  5. Sivaev I. B.; Bregadze V. I. 1,1′-Bis(Ortho-Carborane)-Based Transition Metal Complexes. Coord. Chem. Rev. 2019, 392, 146–176. 10.1016/j.ccr.2019.04.011. [DOI] [Google Scholar]
  6. Chambrier I.; Hughes D. L.; Jeans R. J.; Welch A. J.; Budzelaar P. H. M.; Bochmann M. Do Gold(III) Complexes Form Hydrogen Bonds? An Exploration of AuIII Dicarboranyl Chemistry. Chem.—Eur. J. 2020, 26, 939–947. 10.1002/chem.201904790. [DOI] [PubMed] [Google Scholar]
  7. Martin M. J.; Man W. Y.; Rosair G. M.; Welch A. J. 1,1′-Bis(Ortho-Carborane) as a κ2 Co-Ligand. J. Organomet. Chem. 2015, 798, 36–40. 10.1016/j.jorganchem.2015.04.011. [DOI] [Google Scholar]
  8. Yao Z.-J.; Zhang Y.-Y.; Jin G.-X. Pseudo-Aromatic Bis-o-Carborane Iridium and Rhodium Complexes. J. Organomet. Chem. 2015, 798, 274–277. 10.1016/j.jorganchem.2015.03.028. [DOI] [Google Scholar]
  9. Kirlikovali K. O.; Axtell J. C.; Anderson K.; Djurovich P. I.; Rheingold A. L.; Spokoyny A. M. Fine-Tuning Electronic Properties of Luminescent Pt(II) Complexes via Vertex-Differentiated Coordination of Sterically Invariant Carborane-Based Ligands. Organometallics 2018, 37, 3122–3131. 10.1021/acs.organomet.8b00475. [DOI] [Google Scholar]
  10. Kirlikovali K. O.; Axtell J. C.; Gonzalez A.; Phung A. C.; Khan S. I.; Spokoyny A. M. Luminescent Metal Complexes Featuring Photophysically Innocent Boron Cluster Ligands. Chem. Sci. 2016, 7, 5132–5138. 10.1039/c6sc01146b. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Jeans R. J.; Rosair G. M.; Welch A. J. C,C′-Ru to C,B′-Ru Isomerisation in Bis(Phosphine)Ru Complexes of [1,1′-Bis(Ortho-Carborane)]. Chem. Commun. 2022, 58, 64–67. 10.1039/d1cc06119d. [DOI] [PubMed] [Google Scholar]
  12. Owen D. A.; Hawthorne M. F. Novel Chelated Biscarborane Transition Metal Complexes Formed through Carbon-Metal .Sigma. Bonds. J. Am. Chem. Soc. 1970, 92, 3194–3196. 10.1021/ja00713a051. [DOI] [Google Scholar]
  13. Harwell D. E.; McMillan J.; Knobler C. B.; Hawthorne M. F. Structural Characterization of Representative d7, d8 , and d 9 Transition Metal Complexes of Bis(o - Carborane). Inorg. Chem. 1997, 36, 5951–5955. 10.1021/ic9706313. [DOI] [PubMed] [Google Scholar]
  14. Mandal D.; Rosair G. M. Exploration of Bis(Nickelation) of 1,1′-Bis(o-Carborane). Crystals 2020, 11, 16. 10.3390/cryst11010016. [DOI] [Google Scholar]
  15. Chan A. P. Y.; Rosair G. M.; Welch A. J. Exopolyhedral Ligand Orientation Controls Diastereoisomer in Mixed-Metal Bis(Carboranes). Molecules 2020, 25, 519. 10.3390/molecules25030519. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Cui C.-X.; Ren S.; Qiu Z.; Xie Z. Synthesis of Carborane-Fused Carbo- and Heterocycles via Zirconacyclopentane Intermediates. Dalton Trans. 2018, 47, 2453–2459. 10.1039/c7dt04751g. [DOI] [PubMed] [Google Scholar]
  17. Wong Y. O.; Smith M. D.; Peryshkov D. v. Reversible Water Activation Driven by Contraction and Expansion of a 12-Vertex-Closo-12-Vertex-Nido Biscarborane Cluster. Chem. Commun. 2016, 52, 12710–12713. 10.1039/c6cc06955j. [DOI] [PubMed] [Google Scholar]
  18. Wong Y. O.; Smith M. D.; Peryshkov D. v. Synthesis of the First Example of the 12-Vertex-Closo/12-Vertex-Nido Biscarborane Cluster by a Metal-Free B–H Activation at a Phosphorus(III) Center. Chem.—Eur. J. 2016, 22, 6764–6767. 10.1002/chem.201601194. [DOI] [PubMed] [Google Scholar]
  19. Yruegas S.; Axtell J. C.; Kirlikovali K. O.; Spokoyny A. M.; Martin C. D. Synthesis of 9-Borafluorene Analogues Featuring a Three-Dimensional 1,1′-Bis(o-Carborane) Backbone. Chem. Commun. 2019, 55, 2892–2895. 10.1039/c8cc10087j. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Axtell J. C.; Kirlikovali K. O.; Dziedzic R. M.; Gembicky M.; Rheingold A. L.; Spokoyny A. M. Magnesium Reagents Featuring a 1,1′-Bis(o-carborane) Ligand Platform. Eur. J. Inorg. Chem. 2017, 2017, 4411–4416. 10.1002/ejic.201700604. [DOI] [Google Scholar]
  21. Zhang C.; Wang J.; Lin Z.; Ye Q. Synthesis, Characterization, and Properties of Three-Dimensional Analogues of 9-Borafluorenes. Inorg. Chem. 2022, 61, 18275–18284. 10.1021/acs.inorgchem.2c03111. [DOI] [PubMed] [Google Scholar]
  22. Riley L. E.; Krämer T.; McMullin C. L.; Ellis D.; Rosair G. M.; Sivaev I. B.; Welch A. J. Large, Weakly Basic Bis(Carboranyl)Phosphines: An Experimental and Computational Study. Dalton Trans. 2017, 46, 5218–5228. 10.1039/c7dt00485k. [DOI] [PubMed] [Google Scholar]
  23. Schroeder H.; Papetti S.; Alexander R. P.; Sieckhaus J. F.; L H. T. Icosahedral carboranes. XI. Germanium and Tin Derivatives of o-m-and p-Carborane and Their Polymers. Inorg. Chem. 1969, 8, 2444–2449. 10.1021/ic50081a039. [DOI] [Google Scholar]
  24. Bregadze V. I.; Dzhashiashvili T. K.; Sadzhaya D. N.; Petriashvili M. v.; Ponomareva O. B.; Shcherbina T. M.; Kampel’ V. T.; Kukushkina L. B.; Rochev V. Y.; Godovikov N. N. Carborane Derivatives with Boron-Tin Bond. Bull. Acad. Sci. USSR, Div. Chem. Sci. 1983, 32, 824–827. 10.1007/bf00953487. [DOI] [Google Scholar]
  25. Zakharkin L. I.; Bregadze V. I.; Okhlobystin O. Y. Synthesis of Organoelement Derivatives of Barenes (Carboranes). J. Organomet. Chem. 1965, 4, 211–216. 10.1016/s0022-328x(00)94161-5. [DOI] [Google Scholar]
  26. Lee J.-D.; Kim S.-J.; Yoo D.; Ko J.; Cho S.; Kang S. O. Synthesis and Reactivity of Intramolecularly Stabilized Organotin Compounds Containing the C,N-Chelating o-Carboranylamino Ligand [o-C2B10H10(CH2NMe2)-C,N]- (CabC,N). X-Ray Structures of (CabC,N)SnR2X (R = Me, X = Cl; R = Ph, X = Cl), (CabC,N)2Hg, and [(CabC,N)SnMe2]2. Organometallics 2000, 19, 1695–1703. 10.1021/om990935s. [DOI] [Google Scholar]
  27. Lee T.; Lee S. W.; Jang H. G.; Kang S. O.; Ko J. Synthesis and Reactivity of Organotin Compounds Containing the C,P-Chelating o-Carboranylphosphino Ligand [o-C2B10H10PPh2-C,P](CabC,P). X-Ray Structures of (CabC,CH2P)SnMe2Br, [(CabC,P)SnMe2]2Pd, and [(CabC,P)SnMe2]Pd(PEt3)Cl. Organometallics 2001, 20, 741–748. 10.1021/om0007872. [DOI] [Google Scholar]
  28. Gielen M.; Kayser F.; Zhidkova O. B.; Kampel V. T.; Bregadze V. l.; de Vos D.; Biesemans M.; Mahieu B.; Willem R. Synthesis, Characterization and In Vitro Antitumour Activity of Novel Organotin Derivatives of 1,2- and 1,7-Dicarba-Closo-Dodecaboranes. Met. Base. Drugs 1995, 2, 37–42. 10.1155/mbd.1995.37. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Dostál L.; Růžička A.; Jambor R. Synthesis of Me2LSn(o-CH3–C2B10H10): Crystal Structure of Sn←O Intramolecularly Coordinated Organotin Compound Containing 1-Methyl-o-Carborane. Inorg. Chim. Acta. 2010, 363, 2051–2054. 10.1016/j.ica.2009.06.012. [DOI] [Google Scholar]
  30. Lee J.-D.; Kim H.-S.; Han W.-S.; Kang S. O. Chiral Organotin Complexes Stabilized by C,N-Chelating Oxazolinyl-o-Carboranes. J. Organomet. Chem. 2010, 695, 463–468. 10.1016/j.jorganchem.2009.10.030. [DOI] [Google Scholar]
  31. Nakamura H.; Aoyagi K.; Yamamoto Y. O-Carborane as a Novel Protective Group for Aldehydes and Ketones. J. Org. Chem. 1997, 62, 780–781. 10.1021/jo962130p. [DOI] [Google Scholar]
  32. Nakamura H.; Yamamoto Y. Novel Addition and [3+2] Cycloaddition Reactions of Stannyl- and Silyl-Ortho-Carboranes to Carbonyl Compounds. Collect. Czech. Chem. Commun. 1999, 64, 829–846. 10.1135/cccc19990829. [DOI] [Google Scholar]
  33. Lee C.; Lee J.; Lee S. W.; Kang S. O.; Ko J. Synthesis and Reactivity of 1,2-Bis(Chlorodimethylgermyl)Carborane and 1,2-Bis(Bromodimethylstannyl)Carborane. Inorg. Chem. 2002, 41, 3084–3090. 10.1021/ic0110878. [DOI] [PubMed] [Google Scholar]
  34. Batsanov A. S.; Fox M. A.; Hibbert T. G.; Howard J. A. K.; Kivekäs R.; Laromaine A.; Sillanpää R.; Viñas C.; Wade K. Sulfur, Tin and Gold Derivatives of 1-(2′-Pyridyl)-Ortho-Carborane, 1-R-2-X-1,2-C2B10H10 (R = 2′-Pyridyl, X = SH, SnMe3 or AuPPh3). Dalton Trans. 2004, 3822–3828. 10.1039/b411099d. [DOI] [PubMed] [Google Scholar]
  35. Dröse P.; Hrib C. G.; Edelmann F. T. Carboranylamidinates. J. Am. Chem. Soc. 2010, 132, 15540–15541. 10.1021/ja108051u. [DOI] [PubMed] [Google Scholar]
  36. Harmgarth N.; Gräsing D.; Dröse P.; Hrib C. G.; Jones P. G.; Lorenz V.; Hilfert L.; Busse S.; Edelmann F. T. Novel Inorganic Heterocycles from Dimetalated Carboranylamidinates. Dalton Trans. 2014, 43, 5001–5013. 10.1039/c3dt52751d. [DOI] [PubMed] [Google Scholar]
  37. Harmgarth N.; Liebing P.; Förster A.; Hilfert L.; Busse S.; Edelmann F. T. Spontaneous vs. Base-Induced Dehydrochlorination of Group 14 Ortho-Carboranylamidinates. Eur. J. Inorg. Chem. 2017, 2017, 4473–4479. 10.1002/ejic.201700500. [DOI] [Google Scholar]
  38. Crujeiras P.; Rodríguez-Rey J. L.; Sousa-Pedrares A. Coordinating Ability of the Iminophosphorane Group in Ortho-Carborane Derivatives. Eur. J. Inorg. Chem. 2017, 2017, 4653–4667. 10.1002/ejic.201700487. [DOI] [PubMed] [Google Scholar]
  39. Neumann W. P. Germylenes and Stannylenes. Chem. Rev. 1991, 91, 311–334. 10.1021/cr00003a002. [DOI] [Google Scholar]
  40. Tokitoh N.; Okazaki R. Recent Topics in the Chemistry of Heavier Congeners of Carbenes. Coord. Chem. Rev. 2000, 210, 251–277. 10.1016/s0010-8545(00)00313-1. [DOI] [Google Scholar]
  41. Product Subclass 7: Stannylenes. In Category 1, Organometallics; Moloney M. G., Ed.; Georg Thieme Verlag: Stuttgart, 2003. [Google Scholar]
  42. Ren S.; Xie Z. A Facile and Practical Synthetic Route to 1,1′-Bis(o-Carborane). Organometallics 2008, 27, 5167–5168. 10.1021/om8005323. [DOI] [Google Scholar]
  43. Fulmer G. R.; Miller A. J. M.; Sherden N. H.; Gottlieb H. E.; Nudelman A.; Stoltz B. M.; Bercaw J. E.; Goldberg K. I. NMR Chemical Shifts of Trace Impurities: Common Laboratory Solvents, Organics, and Gases in Deuterated Solvents Relevant to the Organometallic Chemist. Organometallics 2010, 29, 2176–2179. 10.1021/om100106e. [DOI] [Google Scholar]
  44. Kazakov G. S.; Sivaev I. B.; Suponitsky K. Y.; Kirilin A. D.; Bregadze V. I.; Welch A. J. Facile Synthesis of Closo-Nido Bis(Carborane) and Its Highly Regioselective Halogenation. J. Organomet. Chem. 2016, 805, 1–5. 10.1016/j.jorganchem.2016.01.009. [DOI] [Google Scholar]
  45. Popescu A.-R.; Musteti A. D.; Ferrer-Ugalde A.; Viñas C.; Núñez R.; Teixidor F. Influential Role of Ethereal Solvent on Organolithium Compounds: The Case of Carboranyllithium. Chem.—Eur. J. 2012, 18, 3174–3184. 10.1002/chem.201102626. [DOI] [PubMed] [Google Scholar]
  46. Thomas R. Ll.; Rosair G. M.; Welch A. J. Synthesis and Molecular Structure of Dicarbaboryl Ethenes and an Unexpected Dimetallated Derivative. Chem. Commun. 1996, 1327. 10.1039/cc9960001327. [DOI] [Google Scholar]
  47. Wiesboeck R. A.; Hawthorne M. F. Dicarbaundecaborane(13) and Derivatives. J. Am. Chem. Soc. 1964, 86, 1642–1643. 10.1021/ja01062a042. [DOI] [Google Scholar]
  48. Hawthorne M. F.; Young D. C.; Garrett P. M.; Owen D. A.; Schwerin S. G.; Tebbe F. N.; Wegner P. A. Preparation and Characterization of the (3)-1,2- and (3)-1,7-Dicarbadodecahydroundecaborate(-1) Ions. J. Am. Chem. Soc. 1968, 90, 862–868. 10.1021/ja01006a006. [DOI] [Google Scholar]
  49. Hawthorne M. F.; Owen D. A.; Wiggins J. W. Degradation of Biscarborane. Inorg. Chem. 1971, 10, 1304–1306. 10.1021/ic50100a042. [DOI] [Google Scholar]
  50. Aleena M. B.; Philip R. M.; Anilkumar G. Advances in Non-palladium-catalysed Stille Couplings. Appl. Organomet. Chem. 2021, 35, e6430 10.1002/aoc.6430. [DOI] [Google Scholar]
  51. Yang X.; Jiang W.; Knobler C. B.; Mortimer M. D.; Hawthorne M. F. The Synthesis and Structural Characterization of Carborane Oligomers Connected by Carbon-Carbon and Carbon-Boron Bonds between Icosahedra. Inorg. Chim. Acta. 1995, 240, 371–378. 10.1016/0020-1693(95)04556-2. [DOI] [Google Scholar]
  52. Pyykkö P.; Atsumi M. Molecular Single-Bond Covalent Radii for Elements 1-118. Chem.—Eur. J. 2009, 15, 186–197. 10.1002/chem.200800987. [DOI] [PubMed] [Google Scholar]
  53. Clegg W.; Harrington R. W.. CCDC 2055793: Experimental Crystal Structure Determination; CSD Communication, 2021. [Google Scholar]
  54. Iwamoto T.; Masuda H.; Ishida S.; Kabuto C.; Kira M. Addition of Stable Nitroxide Radical to Stable Divalent Compounds of Heavier Group 14 Elements. J. Am. Chem. Soc. 2003, 125, 9300–9301. 10.1021/ja0356784. [DOI] [PubMed] [Google Scholar]
  55. Yan C.; Li Z.; Xiao X.; Wei N.; Lu Q.; Kira M. Reversible Stannylenoid Formation from the Corresponding Stannylene and Cesium Fluoride. Angew. Chem., Int. Ed. 2016, 55, 14784–14787. 10.1002/anie.201608162. [DOI] [PubMed] [Google Scholar]
  56. Schäfer A.; Saak W.; Haase D.; Müller T. Persistent Dialkyl(Silyl)Stannylium Ions. J. Am. Chem. Soc. 2011, 133, 14562–14565. 10.1021/ja206338u. [DOI] [PubMed] [Google Scholar]
  57. Kira M.; Yauchibara R.; Hirano R.; Kabuto C.; Sakurai H. Chemistry of Organosilicon Compounds. 287. Synthesis and x-Ray Structure of the First Dicoordinate Dialkylstannylene That Is Monomeric in the Solid State. J. Am. Chem. Soc. 1991, 113, 7785–7787. 10.1021/ja00020a064. [DOI] [Google Scholar]
  58. Saito M.; Shiratake M.; Tajima T.; Guo J. D.; Nagase S. Synthesis and Structure of the Dithienostannole Anion. J. Organomet. Chem. 2009, 694, 4056–4061. 10.1016/j.jorganchem.2009.08.026. [DOI] [Google Scholar]
  59. Kavara A.; Kampf J. W.; Banaszak Holl M. M. Direct Formation of Propargyltin Compounds via C–H Activation. Organometallics 2008, 27, 2896–2897. 10.1021/om800132h. [DOI] [Google Scholar]
  60. Kavara A.; Kheir M. M.; Kampf J. W.; Banaszak Holl M. M. Aryl Halide Radical Clocks as Probes of Stannylene/Aryl Halide C–H Activation Rates. J. Inorg. Organomet. Polym. Mater. 2014, 24, 250–257. 10.1007/s10904-013-9990-y. [DOI] [Google Scholar]
  61. Yan C.; Xu Z.; Xiao X.-Q.; Li Z.; Lu Q.; Lai G.; Kira M. Reactions of an Isolable Dialkylstannylene with Carbon Disulfide and Related Heterocumulenes. Organometallics 2016, 35, 1323–1328. 10.1021/acs.organomet.6b00208. [DOI] [Google Scholar]
  62. Kavara A.; Cousineau K. D.; Rohr A. D.; Kampf J. W.; Banaszak Holl M. M. A Stannylene/Aryl Iodide Reagent for Allylic CH Activation and Double Bond Addition Chemistry. Organometallics 2008, 27, 1041–1043. 10.1021/om8000108. [DOI] [Google Scholar]
  63. Izod K.; McFarlane W.; Tyson B. V.; Carr I.; Clegg W.; Harrington R. W. Stabilization of a Dialkylstannylene by Unusual B–H···Sn γ-Agostic-Type Interactions. A Structural, Spectroscopic, and DFT Study. Organometallics 2006, 25, 1135–1143. 10.1021/om0600036. [DOI] [Google Scholar]
  64. Krebs K. M.; Wiederkehr J.; Schneider J.; Schubert H.; Eichele K.; Wesemann L. η3 -Allyl Coordination at Tin(II)-Reactivity towards Alkynes and Benzonitrile. Angew. Chem., Int. Ed. 2015, 54, 5502–5506. 10.1002/anie.201500386. [DOI] [PubMed] [Google Scholar]
  65. Veith M.; Belot C.; Huch V.; Zimmer M. Influence of the Solvent on the Formation of New Tin(II) Methoxides Containing Thienyl Substituents: Crystal Structure and NMR Investigations. Z. Anorg. Allg. Chem. 2009, 635, 942–948. 10.1002/zaac.200900023. [DOI] [Google Scholar]
  66. Huang M.; Kireenko M. M.; Lermontova E. Kh.; Churakov A. V.; Oprunenko Y. F.; Zaitsev K. V.; Sorokin D.; Harms K.; Sundermeyer J.; Zaitseva G. S.; Karlov S. S. Novel Stannylenes Stabilized with Diethylenetriamido and Related Amido Ligands: Synthesis, Structure, and Chemical Properties. Z. Anorg. Allg. Chem. 2013, 639, 502–511. 10.1002/zaac.201200552. [DOI] [Google Scholar]
  67. Arii H.; Matsuo M.; Nakadate F.; Mochida K.; Kawashima T. Coordination of a Chiral Tin(Ii) Cation Bearing a Bis(Oxazoline) Ligand with Tetrahydrofuran Derivatives. Dalton Trans. 2012, 41, 11195. 10.1039/c2dt31187a. [DOI] [PubMed] [Google Scholar]
  68. Eisler D. J.; Chivers T. Chalcogenide Derivatives of Imidotin Cage Complexes. Chem.—Eur. J. 2006, 12, 233–243. 10.1002/chem.200500849. [DOI] [PubMed] [Google Scholar]
  69. McGeary M. J.; Cayton R. H.; Folting K.; Huffman J. C.; Caulton K. G. Potassium Triphenylsiloxide “-Ate” Compounds of Tin(II): Molecular and Separated Ion Forms and Variable Potassium Coordination Numbers. Polyhedron 1992, 11, 1369–1382. 10.1016/s0277-5387(00)83368-9. [DOI] [Google Scholar]
  70. Pu L.; Phillips A. D.; Richards A. F.; Stender M.; Simons R. S.; Olmstead M. M.; Power P. P. Germanium and Tin Analogues of Alkynes and Their Reduction Products. J. Am. Chem. Soc. 2003, 125, 11626–11636. 10.1021/ja035711m. [DOI] [PubMed] [Google Scholar]
  71. Becker M.; Förster C.; Franzen C.; Hartrath J.; Kirsten E.; Knuth J.; Klinkhammer K. W.; Sharma A.; Hinderberger D. Persistent Radicals of Trivalent Tin and Lead. Inorg. Chem. 2008, 47, 9965–9978. 10.1021/ic801198p. [DOI] [PubMed] [Google Scholar]
  72. Zheng X.; Crumpton A. E.; Protchenko A. V.; Heilmann A.; Ellwanger M. A.; Aldridge S. Disproportionation and Ligand Lability in Low Oxidation State Boryl-Tin Chemistry. Chem.—Eur. J. 2023, 29, e202203395 10.1002/chem.202203395. [DOI] [PMC free article] [PubMed] [Google Scholar]
  73. Endo Y.; Songkram C.; Ohta K.; Kaszynski P.; Yamaguchi K. Distorted Benzene Bearing Two Bulky Substituents on Adjacent Positions: Structure of 1,2-Bis(1,2-Dicarba-Closo-Dodecaboran-1-Yl)Benzene. Tetrahedron Lett. 2005, 46, 699–702. 10.1016/j.tetlet.2004.11.143. [DOI] [Google Scholar]
  74. Endo Y.; Songkram C.; Ohta K.; Yamaguchi K. Synthesis of Distorted Molecules Based on Spatial Control with Icosahedral Carboranes. J. Organomet. Chem. 2005, 690, 2750–2756. 10.1016/j.jorganchem.2005.01.014. [DOI] [Google Scholar]
  75. Harder R. A.; Hugh MacBride J. A.; Rivers G. P.; Yufit D. S.; Goeta A. E.; Howard J. A. K.; Wade K.; Fox M. A. Studies on Bis(1′-Ortho-Carboranyl)Benzenes and Bis(1′-Ortho-Carboranyl)Biphenyls. Tetrahedron 2014, 70, 5182–5189. 10.1016/j.tet.2014.05.102. [DOI] [Google Scholar]
  76. Wrackmeyer B.119Sn-NMR Parameters, Annual Reports on NMR Spectroscopy; Elesiver, 1985; pp 73–186. [Google Scholar]
  77. Otera J. 119Sn Chemical Shifts in five- and six-coordinate organotin chelates. J. Organomet. Chem. 1981, 221, 57–61. 10.1016/s0022-328x(00)81028-1. [DOI] [Google Scholar]
  78. Mitchell T. N. Carbon-13 NMR Investigations on Organotin Compounds. J. Organomet. Chem. 1973, 59, 189–197. 10.1016/s0022-328x(00)95034-4. [DOI] [Google Scholar]
  79. Wrackmeyer B. Long-Range Nuclear Spin-Spin Coupling between 11B and 13C, 29Si or 119Sn: A Promising Tool for Structural Assignment. Polyhedron 1986, 5, 1709–1721. 10.1016/s0277-5387(00)84848-2. [DOI] [Google Scholar]
  80. Abragam A.The Principles of Nuclear Magnetism; Oxford University Press: Oxford, 1961. [Google Scholar]
  81. Suzuki M.; Kubo R. Theoretical Calculation of N.M.R. Spectral Line Shapes. Mol. Phys. 1964, 7, 201–209. 10.1080/00268976300100981. [DOI] [Google Scholar]
  82. Eichler B. E.; Power P. P. Characterization of the Sterically Encumbered Terphenyl-Substituted Species 2,6-Trip2H3C6sn–Sn(Me)2C6H3-2,6-Trip2, an Unsymmetric, Group 14 Element, Methylmethylene, Valence Isomer of an Alkene, Its Related Lithium Derivative 2,6-Trip2H3C6(Me)2Sn–Sn(Li)(Me)C6H3-2,6-Trip2, and the Monomer Sn(t-Bu)C6H3-2,6-Trip2 (Trip = C6H2-2,4,6-i-Pr3). Inorg. Chem. 2000, 39, 5444–5449. 10.1021/ic0005137. [DOI] [PubMed] [Google Scholar]
  83. Kalsi P. S.Spectroscopy of Organic Compounds; New Age International, 2007. [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

om3c00190_si_001.pdf (1MB, pdf)

Articles from Organometallics are provided here courtesy of American Chemical Society

RESOURCES