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Published in final edited form as: Inorg Chem. 2024 Oct 9;63(42):19738–19743. doi: 10.1021/acs.inorgchem.4c02922

Synthetic challenges toward modeling formate dehydrogenases using [WVI≡S] complexes supported by a tetradentate [N2S2]4- ligand

Debashis Basu 1, Connly Yan 1, Neal P Mankad 1,*
PMCID: PMC11972111  NIHMSID: NIHMS2070746  PMID: 39382115

Abstract

This report documents our attempts at synthesizing a terminal [WVI≡S] complex supported by a tetradentate, diamido/dithiolate ligand ([N2S2]4-). The target compound was selected because it would serve as a synthetic model for the active sites of formate dehydrogenase (FDH) enzymes. Although the desired [N2S2]WVI≡S species was observed as a NEt3 adduct by mass spectrometry in one case, generally unwanted side reactions prevented isolation and definitive characterization of the target compound. Instead, isolated products characterized by X-ray crystallography included {[N2S2]H}WVI(S2)Cl from redox chemistry of the terminal sulfide, ([N2S2]WVI)2(μ-[N2S2]) from dissociation of the terminal sulfide, ({[N2S2]H}WV)2(μ-S)2 from metal reduction and μ-sulfide bridge formation, and {[N2S2]H}2 from disulfide bond formation via thiolate redox chemistry. A product formed from adventitious exposure to air/moisture, {[N2S2]H2}WVI(O)2, was also characterized. The diverse range of products formed simply from attempted metalation of the [N2S2]4- ligand with Cl4WVI≡S highlight the synthetic challenges toward building active sites that are structurally faithful to FDH.

Graphical Abstract

graphic file with name nihms-2070746-f0001.jpg

INTRODUCTION

Impending consequences of the climate crisis motivate examinations of ways to recycle gaseous CO2 captured from earth’s atmosphere into valuable products.1 One approach to designing new catalysts for such CO2 transformations is to learn the detailed workings of metalloenzymes such as formate dehydogenases (FDHs), which are capable of interconversion of CO2 and formate (HCO2−) via coupled 2e−/1H+ transfers.2–7 FDH active sites consist of two pyranopterindithiolate cofactors coordinating to a high-valent [MoVI≡S]/[WVI≡S] unit, with cysteinate or selenocysteinate as a sixth ligand in the oxidized state (Figure 1a). This high valent species can capture hydride from HCO2− to extrude CO2 and form a corresponding reduced MIV species; thus, intriguingly, the reduced form must be able to add hydride to CO2 in the reverse direction.8,9 In this context, our interest resides in generating high-valent [MoVI≡S]/[WVI≡S] complexes in thiolate-rich environments to map their intrinsic reactivity. There are only a few terminal [WVI≡S] complexes known in sulfur-rich environments,10–15 and no such terminal [MoVI≡S] complexes are known. The known terminal [WVI≡S] complexes are based on either dithiocarbamate ligands, e.g. [(dtc)3WVI≡S]BF4, [(dtc)2Cl2WVI≡S], and [(dtc)2(S2)WVI≡S] (dtc− = [S2CNR2]−);10,13–15 or dithiolene ligands, e.g [(S2C2Me2)2(SR)WVI≡S]−.11,12 Some of the these complexes require complicated multi-step syntheses that preclude isolation of enough compound to realistically perform reactivity studies. Thus, the literature of biomimetic synthetic models of the FDH active sites is sparse. Synthetic challenges including the propensity of high-valent metal sites to undergo reduction in the presence of negatively charged thiolates (RS−) and the tendency of sulfide (S2-) ligands to form μ-S2- bridges or undergo their own redox processes complicate the pursuit of such targets.

Figure 1.

Figure 1.

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(a) Schematic of the formate dehydrogenase active sites, (b) previously studied model complex, (c) target of this study.

In our previous work, we explored the reactivity of a known15 [WVI≡S] complex, [(dtc)3WVI≡S]BF4 (Figure 1b), toward formate and other potential hydride sources.16 In all cases, H− transfer was outcompeted by reduction of the WVI center via electron transfer. Additionally, the bidentate monoanion, dtc−, was prone to side reactions such as ligand dissociation, sulfur atom extrusion, and formation of W2(μ-dtc) bridges. Based on these observations, our hypothesis was that a FDH mimic might be accessible by increasing the number of anionic ligands supporting the [WVI≡S] unit to suppress electron transfer to WVI and, thereby, enable H− transfer chemistry to take place. We also hypothesized that a multidentate ligand would be better suited to support a FDH mimic than a bidentate ligand by suppressing unwanted processes such as ligand dissociation/rearrangement.

In the current study, we have targeted a [WVI≡S] complex supported by a N2S2-type tetradentate tetra-anion (Figure 1c).17,18 The [N2S2]H4 pro-ligand can be synthesized by following a literature procedure (Figure S1,S2),17 and [N2S2]4- is known to support Fe complexes in various oxidation states (II, III, IV, V)19–22 as well as high-valent early 1st row-transition metals (TiIII, VIV)23–25 and a ReV oxo complex.26 To date, there are no reports of Mo/W chemistry with this ligand. On the other hand, some synthetic model [MoV≡O] chemistry of sulfite oxidase/xanthine oxidase is known for a related, dianionic [N2S2]2- ligand (where N methylated).27–31 Although we have been unable to definitively characterize the targeted “[N2S2]WVI≡S” species, this report summarizes several unexpected challenges we faced along the way. Documenting these challenges systematically will aid future efforts toward constructing FDH mimics and other terminal metal-sulfide target molecules.32

RESULTS & DISCUSSION

Attempts at synthesizing a FDH mimic

The [N2S2]H4 pro-ligand has four acidic protons: the S-H protons (pKa ~ 6–7) are more acidic than the N-H protons (pKa ~ 27). We found that treatment of [N2S2]H4 with moderately strong bases (1:4) such as LiOtBu (pKa ~ 19), Na[N(SiMe3)2] (pKa ~ 26), and NaH (pKa ~ 35) in CH3CN consistently yielded the doubly deprotonated [N2S2]Li2H2 or [N2S2]Na2H2 derivatives (Scheme S1, Figure S3–S5), suggesting the tetra-anionic [N2S2]4- is difficult to produce without metal coordination.

A convenient tungsten precursor to enter this chemistry is Cl4WVI≡S (1), which is readily available by literature methods.33 First, we attempted the reaction of the [N2S2]H4 pro-ligand with 1 in the absence of base in CH2Cl2 at low temperature, hoping to generate [N2S2]WVI≡S with loss of 4 HCl (Scheme S2). Instead, we isolated {[N2S2]H}WVI(S2)Cl (2) that had retained 1 HCl and unexpectedly featured a disulfide (S22-) ligand with a S-S distance of 2.02(1) - 2.03(1) Å for two molecules in the asymmetric unit (Figure 2a). Similar S-S bond lengths of 2.067(5) and 2.208(2) Å were previously determined for 7-coordinate WVIS(S2)(Etdtc)2 and WVIS(S2)(iBudtc)2 complexes.13,16 It is clear from the crystal structure of 2 that one of the nitrogen centers is protonated since it exhibits significant pyramidalization and shows a longer W-N distance (2.22(2) Å for both molecules) than the amido-type W-N bond (2.02(2) Å for both molecules). In the structure of 2, the W center is 7-coordinate and resides in a pseudo-pentagonal bipyramidal geometry with the amine N, amide N, S22-, and one of the thiolate S atoms occupying the equatorial plane. Complex 2 is purple in color with absorbances at 400, 466, 533, and 639 nm in the UV-Visible spectrum (Figure S6). The ESI-MS spectrum of 2 showed a major peak at 520.9466 (m/z) along with other fragmentations (Figure S7). This major peak belongs to [M-Cl]+, i.e. [{[N2S2]H}WVI(S2)]+. IR spectroscopy confirmed the presence of an N-H bond at 3112 cm−1, and a new band at 552 cm−1 is tentatively assigned as a ν(S-S) feature (Figure S8). The 1H NMR spectrum of 2 (Figure S9) exhibited sharp peaks indicating a diamagnetic ground state consistent with the WVI assignment. The same product 2 was isolated from a reaction between 1 and the doubly deprotonated pro-ligand, [N2S2]Li2H2, in CH3CN (Figure S10). A complex mixture of at least three species (vide infra) including 2 was obtained from 1 and [N2S2]H4 in CH2Cl2 at room temperature (Figure S11). The disulfide complex formation may proceed by intermolecular electron transfer and S-S coupling between two terminal sulfido ligands followed by two electron oxidations. In this scenario, half of the W centers stay at WVI to give rise to the disulfide product, whereas the other half is likely reduced to WIV. The possible byproducts could be HCl and {[N2S2]H2}WIVCl2, though we were unable to characterize any WIV species that formed.

Figure 2.

Figure 2.

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X-ray crystal structures of complexes (a) 2 and (b) 3. For 2, only one of two molecules from the asymmetric unit is shown. C-H hydrogens and co-crystallized solvent molecules are omitted, and the N-H hydrogen is shown in a calculated position.

Next, mimicking the reported synthesis conditions for {[N2S2]ReV≡O}−,26 we pursued the reaction of [N2S2]H4 with 1 in the presence of excess (10 equivalents) NaOAc (pKa: 4.76) in MeOH at 80°C, hoping to generate [N2S2]WVI≡S (Scheme S3). Instead, we obtained a homometallic, formally WVI-based dimer, ([N2S2]WVI)2(μ-[N2S2]) (3), containing three ligands in the fully deprotonated, formally [N2S2]4- state. In the crystal structure of 3, each W center is fully chelated by the tetradentate [N2S2] ligand and further bound to one amido and one thiolate donor from a bridging [N2S2] ligand (Figure 2b). Each W center in 3 is 6-coordinate, giving a pseudo-trigonal prismatic geometry. The W-N bonds (~2.01 – 2.09 Å) are similar to other W-Namide bonds in this study. Similarly, the W-S bonds (~2.33–2.39 Å) are typical of W-thiolates.34 The oxidation state assignment of the metal is not straightforward as we found contracted bond lengths for the N-CAr (1.37(1) Å) and S-CAr (1.727(9) Å) set for one aromatic system, indicating possible presence of [C=N] character and redox non-innocence (e.g. semiquinonate radical anion [N2S2].3- character).19 Formal “MoVI/WVI” complexes of bidentate dianionic ligands are known to be trigonal prismatic as evidenced from the structures of Mo/W complexes of various dithioglyoxals and dithiolene ligands such as Mo(S2C2H2)3, Mo/W(S2C2Ph2)3, W[S2C2(CH3)2]3, Mo/W(tdt)3, Mo/W(bdt)3.35,36 These cases also presented challenges with regard to oxidation state assignments. 1H NMR spectroscopy confirmed the diamagnetic nature of 3 (Figure S12). The presence of another species (ligand dimer, to be discussed below) was detected as well from the signature 1H NMR peaks at 3.01, 4.93, 6.53, 6.59, and 7.31 ppm. Complex 3 is green in color (UV-Vis: Figure S13).

Next, we decided to use a weak neutral base such as Et3N (pKa of conjugate acid: 10.7) to avoid the formation of 2 in the presence of HCl or 3 in the presence of an anionic base. We performed the reaction of [N2S2]H4 with 1 in THF in the presence of Et3N starting at low temperature (−78°C, Scheme S4). The [Et3NH]Cl byproduct was obtained as expected (Figure S14, S15). Analysis of the other products revealed the presence of ligand dimer, {[N2S2]H}2 (4) featuring two disulfide bonds (Figure 3a) and a bis(μ-sulfide) dimer, ({[N2S2]H}W)2(μ-S)2 (5, Figure 3b, Figure S16 – S18) in an approximately equimolar ratio based on the relative proton counts from 1H NMR spectroscopy (Figure S16).

Figure 3.

Figure 3.

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X-ray crystal structures of complexes (a) 4 and (b) 5. For 4, only one of two molecules from the asymmetric unit is shown. C-H hydrogens and co-crystallized solvent molecules are omitted, and N-H hydrogens are shown in calculated positions.

The yellow ligand dimer 4 was possibly formed from thiolate oxidation followed by S-S bond formation (Figure S19). The other complex, green-colored 5, is also a dimer. Here, the ligand is most likely in {[N2S2]H}3- protonation state, as one of the W-N bonds (2.29(1) – 2.30(1) Å) at each metal is longer than the other (2.02(1) – 2.020(9) Å). Furthermore, the (μ-S)-W bonds 2.377(4) – 2.406(3) Å) trans to amido nitrogen atoms are significantly longer than for the other bridging sulfides (2.270(4) – 2.302(4) Å) (Figure 3b). Thus, the formal oxidation state of 5 is WV for each tungsten center. The W-W distance is 2.9134(9) Å, raising the possibility of weak or negligible metal-metal bonding. Usually for 6-coordinate W(V)-based [W2(μ-S)2] species, a W-W covalent bond distance should be between 2.78 and 2.84 Å.37–40 Without considering the weak W-W bond, the W centers seem to be 6-coordinated and complex 5 has pseudo-octahedral geometry. Similar centrosymmetric, pseudo-octahedral dimeric structures are known for dianionic WV dimers of dithioglyoxals, e.g. [WV2(μ-S)2(mnt)4]2-, [WV2(μ-S)2(S2C2Ph2)4]2- and [WV2(μ-S)2(S2C2Me2)4]2-, where W-W distances vary from 2.93 to 3.00 Å, also indicating weak or negligible metal-metal bonding.41–44

Putative generation of a FDH model

Interestingly, starting the same reaction of [N2S2]H4 with 1 in THF in the presence of Et3N at room temperature rather than −78°C (Schemes 1 and S4) yielded much less 4 and gave another [N2S2]W-containing compound as the major product (Figure S20–S23), which we tentatively assign as [N2S2]WVI≡S (A). The IR spectrum of A revealed a signature peak at 449 cm−1 possibly belonging to a terminal W≡S bond (Figure S20). This shift to lower energy compared to the W≡S bond in the precursor WSCl4 (554 cm−1) is possibly due to the increased donor ability of the [N2S2]4- donor set relative to a tetrachloride ligand field. The 1H NMR spectrum of A also matches that of one of the products (other than complex 2) obtained from reaction between [N2S2]H4 and 1 in CH2Cl2 at room temperature (Figure S11, S21). High-resolution ESI-MS analysis of this product revealed intense peaks at m/z 486.9504 ([A – H]+) and 586.0640 ([A·NEt3 – H]+) (Figure S23, S24), suggesting that residual triethyl amine acts as a dative ligand to stabilize the target [N2S2]WVI≡S. Unfortunately, even after multiple attempts, we could not get an X-ray quality crystal for this complex. We also attempted to synthesize the benzonitrile adduct [N2S2]W(S)(NCPh) (Scheme S5, Figure S25) from a new precursor compound, WSCl4(NCPh) (Scheme S6, Figure S26, S27), synthesized here for the first time. Once again, we failed to obtain X-ray quality crystals. Thus, although we have preliminary evidence that the target FDH mimic was generated in the form of compound A, we lack definitive characterization.

Scheme 1.

Scheme 1.

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Putative generation of the target compound A.

Degradation products from air exposure

WVI complexes are highly oxophilic, so small amounts of air or moisture can degrade the complexes under study, especially during prolonged crystallization attempts. Here, we document one such examples (Figure 4). The neutral complex, {[N2S2]H2}WVI(O)2 (6), was characterized crystallographically and, presumably, formed from adventitious air exposure during attempted crystallization of A. The assignment of 6 as containing two amino nitrogen atoms was based on charge balance considerations as well as analysis of W-N distances (~2.33 – 2.34 Å). W is in +VI formal oxidation state in this pseudo-octahedral complex. The W-Sthiolate bond lengths are in the typical ~ 2.40 – 2.41 Å range. The two W=O bonds occupy cis positions. A similar structure is known for a related molybdenum complex, {[N2S2]H2}MoVI(O)2.45 The W=O bond lengths (~ 1.73 – 1.74 Å) are slightly longer than the Mo=O distances (~1.69 – 1.72 Å).

Figure 4.

Figure 4.

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X-ray crystal structure of air-oxidized complex 6. C-H hydrogens are omitted, and N-H hydrogens are shown in calculated positions.

CONCLUSIONS

Attempts were made to synthesize a terminal [WVI≡S] complex supported by a tetradentate, tetra-anionic, diamido/dithiolate ligands, with the goal of constructing a FDH active site mimic. Although we did obtain evidence by HRMS for formation of the target compound, these attempts were generally complicated by the tendencies of the terminal sulfide ligand to undergo redox chemistry to form disulfide ligands, bridge between two metals, undergo degradation with trace air/moisture, or dissociate completely. Another complicating factor was the redox-induced formation of disulfide bonds from the thiolate groups of the ancillary ligand. Scheme 2 summarizes the different compounds obtained from attempted metallations of the [N2S2]H4 pro-ligand with WSCl4. We hope that documentation of these unexpected reaction pathways aids future researchers targeting FDH mimics or other terminal metal sulfide compounds.

Scheme 2.

Scheme 2.

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Summary of reactivity observed in this study.

EXPERIMENTAL SECTION

General Considerations.

Synthetic procedures were carried out under a N2 atmosphere inside a MBraun Lab Master glovebox. All glassware was oven-dried before use. All reaction solvents were taken from Glass Contour Solvent System built by Pure Process Technology, LLC,46 and further dried over molecular sieves in the glovebox. Deuterated solvents were degassed and stored over 3-Å molecular sieves. 1H NMR spectra were recorded on Bruker Avance DPX-400 MHz or Bruker Avance DRX-500 MHz spectrometers. FT-IR spectra were recorded on powder samples using a Bruker ALPHA spectrometer fitted with a diamond-ATR detection unit. UV-Visible spectra were recorded on JASCO V-770 spectrophotometer. X-ray diffraction data collection was performed using a Bruker D8 QUEST ECO diffractometer under its default manufacturer settings, and standard solution/refinement protocols were followed.47,48 High resolution ESI spectra were recorded by using a Q-TOF mass instrument at the School of Chemical Sciences Mass Spectrometry Laboratory at University of Illinois at Urbana-Champaign (UIUC). WCl6, (Me3Si)2S, 2-amino-thiophenol, glyoxal, LiAlH4, LiOMe, Na2SO4, and NaOAc were purchased commercially and used as received. PhCN and Et3N were purchased commercially and then degassed by freeze-pump-thaw and stored in the glovebox over molecular sieves. Elemental analysis measurements for C, H, N, S were performed from Atlantic Microlab, Inc. Detailed synthetic procedures and characterization data are provided as Supporting Information.

Supplementary Material

SI

SYNOPSIS.

Attempts to synthesize a terminal [WVI≡S] complex supported by a tetradentate, tetraanionic [N2S2]4- ligand led to unexpected but interesting compounds characterized by X-ray crystallography.

ACKNOWLEDGMENT

Funding was provided by NIH/NIGMS under grant R35 GM140850. Dr. Simon Gersib (UIC) assisted with X-ray crystallography.

Footnotes

Supporting Information. The following files are available free of charge.

Synthetic methods and spectral/structural characterization data (PDF)

Crystallographic data (CIF)

REFERENCES

  • (1).Lewis NS; Nocera DG Powering the Planet: Chemical Challenges in Solar Energy Utilization. Proc. Natl. Acad. Sci 2006, 103 (43), 15729–15735. 10.1073/pnas.0603395103. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • (2).Fogeron T; Li Y; Fontecave M Formate Dehydrogenase Mimics as Catalysts for Carbon Dioxide Reduction. Molecules 2022, 27 (18), 5989. 10.3390/molecules27185989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • (3).Liu M; Nazemi A; Taylor MG; Nandy A; Duan C; Steeves AH; Kulik HJ Large-Scale Screening Reveals That Geometric Structure Matters More Than Electronic Structure in the Bioinspired Catalyst Design of Formate Dehydrogenase Mimics. ACS Catal. 2022, 12 (1), 383–396. 10.1021/acscatal.1c04624. [DOI] [Google Scholar]
  • (4).Groysman S; Holm RH Biomimetic Chemistry of Iron, Nickel, Molybdenum, and Tungsten in Sulfur-Ligated Protein Sites. Biochemistry 2009, 48 (11), 2310–2320. 10.1021/bi900044e. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • (5).Leimkühler S Metal-Containing Formate Dehydrogenases, a Personal View. Molecules 2023, 28 (14), 5338. 10.3390/molecules28145338. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • (6).Chen H; Huang Y; Sha C; Moradian JM; Yong Y-C; Fang Z Enzymatic Carbon Dioxide to Formate: Mechanisms, Challenges and Opportunities. Renew. Sustain. Energy Rev 2023, 178, 113271. 10.1016/j.rser.2023.113271. [DOI] [Google Scholar]
  • (7).Kobayashi A; Taketa M; Sowa K; Kano K; Higuchi Y; Ogata H Structure and Function Relationship of Formate Dehydrogenases: An Overview of Recent Progress. IUCrJ 2023, 10 (5), 544–554. 10.1107/S2052252523006437. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • (8).Yang JY; Kerr TA; Wang XS; Barlow JM Reducing CO 2 to HCO 2 – at Mild Potentials: Lessons from Formate Dehydrogenase. J. Am. Chem. Soc 2020, 142 (46), 19438–19445. 10.1021/jacs.0c07965. [DOI] [PubMed] [Google Scholar]
  • (9).Meneghello M; Uzel A; Broc M; Manuel RR; Magalon A; Léger C; Pereira IAC; Walburger A; Fourmond V Electrochemical Kinetics Support a Second Coordination Sphere Mechanism in Metal‐Based Formate Dehydrogenase. Angew. Chem. Int. Ed 2023, 62 (6), e202212224. 10.1002/anie.202212224. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • (10).FEDIN VP; MIRONOV Yu. V.; VIROVETS AV; PODBEREZSKAYA NV; FEDOROV V. Ye.; SEMYANNIKOV PP IALKYLDITHIOCARBAMATE COMPLEXES OF TUNGSTEN(W). SYNTHiESIS, PROPERTIES AND STRUCTURE OF THIODICHLOROBIS(DIMETHYLD~HIOCARBAMATO)TUNGSTEN(VI). Polyhedron 1992, 11, 279. [Google Scholar]
  • (11).Jiang J; Holm RH An Expanded Set of Functional Groups in Bis(Dithiolene)Tungsten(IV,VI) Complexes Related to the Active Sites of Tungstoenzymes, Including W IV −SR and W VI −O(SR). Inorg. Chem 2004, 43 (4), 1302–1310. 10.1021/ic030301k. [DOI] [PubMed] [Google Scholar]
  • (12).Lorber C; Donahue JP; Goddard CA; Nordlander E; Holm RH Synthesis, Structures, and Oxo Transfer Reactivity of Bis(Dithiolene)Tungsten(IV,VI) Complexes Related to the Active Sites of Tungstoenzymes. J. Am. Chem. Soc 1998, 120 (32), 8102–8112. 10.1021/ja981015o. [DOI] [Google Scholar]
  • (13).Pan W-H; Halbert TR; Hutchings LL; Stiefel EI Ligand and Induced Internal Electron Transfer Pathways to New Mo–S and W–S Dithiocarbamate Complexes. J Chem Soc Chem Commun 1985, No. 13, 927–929. 10.1039/C39850000927. [DOI] [Google Scholar]
  • (14).Young G MICHAEL RSNOW, EDWARD R. T. TIEKINK. Inorganica Chim. Acta 1988, 150, 161. [Google Scholar]
  • (15).Young CG; BrownleeB RTC Tris(N,N-Di&yldithiocarbamato- S,S’) Thiotungsten(vr) Complexes and the X-Ray Crystal Structure of [WS(S2CNEt2)3B] F4.
  • (16).Basu D; Subasinghe SMS; Mankad NP Reactivity of a Dithiocarbamate-Ligated [W VI ≡S] Complex with Hydride Donors: Toward a Synthetic Mimic of Formate Dehydrogenase. Inorg. Chem 2023, 62 (16), 6332–6338. 10.1021/acs.inorgchem.3c00086. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • (17).Sellmann D; Emig S; Heinemann FW; Knoch F Ubergangsmetallkomplexe Mit Schwefelliganden, CXXXIII [1]. Synthese, Struktur Und Eigenschaften Neuer Fe11-Komplexe Mit [FeN2S2]-Gerüsten. Z Naturforsch 1998, 53 b, 1461. [Google Scholar]
  • (18).Presow SR; Ghosh M; Bill E; Weyhermüller T; Wieghardt K Molecular and Electronic Structures of New Iron Complexes Containing N,S-Coordinated o-Iminothionebenzosemiquinonate(1-) π Radical Ligands: An Experimental and Density Functional Theoretical Study. Inorganica Chim. Acta 2011, 374 (1), 226–239. 10.1016/j.ica.2011.02.036. [DOI] [Google Scholar]
  • (19).Ghosh P; Bill E; Weyhermüller T; Wieghardt K Molecular and Electronic Structures of Iron Complexes Containing N,S-Coordinated, Open-Shell o -Iminothionebenzosemiquinonate(1−) π Radicals. J. Am. Chem. Soc 2003, 125 (13), 3967–3979. 10.1021/ja021409m. [DOI] [PubMed] [Google Scholar]
  • (20).Ghosh P; Bill E; Weyhermüller T; Neese F; Wieghardt K Noninnocence of the Ligand Glyoxal-Bis(2-Mercaptoanil). The Electronic Structures of [Fe(Gma)] 2, [Fe(Gma)(Py)]·py, [Fe(Gma)(CN)] 1 - /0, [Fe(Gma)I], and [Fe(Gma)(PR 3) n] (n = 1, 2). Experimental and Theoretical Evidence for “Excited State” Coordination. J. Am. Chem. Soc 2003, 125 (5), 1293–1308. 10.1021/ja021123h. [DOI] [PubMed] [Google Scholar]
  • (21).Sellmann D; Emig S; Heinemann FW; Knoch F A Convenient Way to Novel Fe IV Complexes with Mixed N/S/P Coordination Spheres and “Innocent” Ligands. Angew. Chem. Int. Ed. Engl 1997, 36 (11), 1201–1203. 10.1002/anie.199712011. [DOI] [Google Scholar]
  • (22).Sellmann D; Emig S; Heinemann FW Stabilization of Iron Centers in High Oxidation State in the Mononuclear Complex [Fe v (I)(′N 2 S 2 ′)]. Angew. Chem. Int. Ed. Engl 1997, 36 (16), 1734–1736. 10.1002/anie.199717341. [DOI] [Google Scholar]
  • (23).Tsagkalidis W; Rehder D Characterization of Bio-Related Vanadium and Zinc Complexes Containing Tetradentate Dithiolate-Disulfide, -Diamine and -Amine-Amide Ligands. JBIC J. Biol. Inorg. Chem 1996, 1 (6), 507–514. 10.1007/s007750050085. [DOI] [Google Scholar]
  • (24).Tsagkalidis W; Rodewald D; Rehder D Coordination and Oxidation of N,N’-Bis(o-Mercaptophenyl)Ethylenediamine (HSNNSH) by VO2+: {V(-SNNS-)}4(.Mu.-O)4 and Tetrabenzotetrathiatetraazacycloeicosane. Inorg. Chem 1995, 34 (7), 1943–1945. 10.1021/ic00111a047. [DOI] [Google Scholar]
  • (25).Shaban SY; Ramadan AE-MM; Heinemann FW Titanium Isopropoxide Complexes Containing Diamine Bis-Thiolato Based [N2S2]2− Ligands; Effect of Steric Bulk on Coordination Features. Inorg. Chem. Commun 2012, 20, 135–137. 10.1016/j.inoche.2012.02.035. [DOI] [Google Scholar]
  • (26).Chi DY; Wilson SR; Katzenellenbogen JA Crystal Structure of a Bis(Amido)Bis(Thiolato)Oxorhenium(V) Complex That Forms a Methanol-Solvated Salt with Calcium Extracted from Silica Gel. Inorg. Chem 1995, 34 (6), 1624–1625. 10.1021/ic00110a048. [DOI] [Google Scholar]
  • (27).Barnard KR; Bruck M; Huber S; Grittini C; Enemark JH; Gable RW; Wedd AG Mononuclear and Binuclear Molybdenum(V) Complexes of the Ligand N, N ‘-Dimethyl- N, N ‘-Bis(2-Mercaptophenyl)Ethylenediamine: Geometric Isomers . Inorg. Chem 1997, 36 (4), 637–649. 10.1021/ic960848h. [DOI] [Google Scholar]
  • (28).Cosper MM; Neese F; Astashkin AV; Carducci MD; Raitsimring AM; Enemark JH Determination of the g -Tensors and Their Orientations for Cis, Trans -(L- N 2 S 2)Mo V OX (X = Cl, SCH 2 Ph) by Single-Crystal EPR Spectroscopy and Molecular Orbital Calculations. Inorg. Chem 2005, 44 (5), 1290–1301. 10.1021/ic0483850. [DOI] [PubMed] [Google Scholar]
  • (29).Singh R; Spence JT; George GN; Cramer SP Oxo-Molybdenum(V) Complexes with Sulfide and Hydrogensulfide Ligands: Models for the Molybdenum(V) Centers of Xanthine Oxidase and Xanthine Dehydrogenase. Inorg. Chem 1989, 28 (1), 8–10. 10.1021/ic00300a005. [DOI] [Google Scholar]
  • (30).Dowerah D; Spence JT; Singh R; Wedd AG; Wilson GL; Farchione F; Enemark JH; Kristofzski J; Bruck M Molybdenum(VI) and Molybdenum(V) Complexes with N,N’-Dimethyl-N,N’-Bis(2-Mercaptophenyl)Ethylenediamine. Electrochemical and Electron Paramagnetic Resonance Models for the Molybdenum(VI/V) Centers of the Molybdenum Hydroxylases and Related Enzymes. J. Am. Chem. Soc 1987, 109 (19), 5655–5665. 10.1021/ja00253a016. [DOI] [Google Scholar]
  • (31).Mader ML; Carducci MD; Enemark JH Analogues for the Molybdenum Center of Sulfite Oxidase: Oxomolybdenum(V) Complexes with Three Thiolate Sulfur Donor Atoms. Inorg. Chem 2000, 39 (3), 525–531. 10.1021/ic990768o. [DOI] [PubMed] [Google Scholar]
  • (32).Baeza Cinco MÁ; Hayton TW Progress toward the Isolation of Late Metal Terminal Sulfides. Eur. J. Inorg. Chem 2020, 2020 (38), 3613–3626. 10.1002/ejic.202000600. [DOI] [Google Scholar]
  • (33).Gibson VC; Kee TP; Shaw A The Use of Silylethers and Silylthioethers in Syntheses of Oxohalide and Thiohalide Compounds of Molybdenum and Tungsten. Polyhedron 1990, 9 (18), 2293–2298. 10.1016/S0277-5387(00)86956-9. [DOI] [Google Scholar]
  • (34).Barnard KR; Gable RW; Wedd AG Dioxo-, Oxothio- and Dithio-Tungsten(VI) and Tungsten(V) Complexes of the Ligand N,Nb-Dimethyl-N,Nb-Bis(2-Mercaptophenyl)Ethylenediamine.
  • (35).Stiefel EI; Eisenberg R; Rosenberg RC; Gray HB Characterization and Electronic Structures of Six-Coordinate Trigonal-Prismatic Complexes. J. Am. Chem. Soc 1966, 88 (13), 2956–2966. 10.1021/ja00965a015. [DOI] [Google Scholar]
  • (36).Smith AE; Schrauzer GN; Mayweg VP; Heinrich W The Crystal and Molecular Structure of MoS6C6H6. J Am Chem Soc 1965, 87, 5798–5799. [Google Scholar]
  • (37).Bino A; Cotton FA; Dori Z; Sekutowski JC Preparation and Characterization of Di-g-Sulfido Binuclear Compounds of W(IV) and W(V). Unambiguous Examples of Formal Single and Double Bonds between Tungsten Atoms. [Google Scholar]
  • (38).Shibahara T; Izumori Y; Kubota R; Kuroya H Preparation of Tungsten(V) Aqua Ion, W2O2S2(Aq)2+, and X-Ray Structure of Di-μ-Sulfido-Bis [(Cysteinato)Oxotungstate(V)I Ion, [W2O2S2(Cys)2]2-. Chem Lett 1987, 2327–2330. [Google Scholar]
  • (39).Simonnet-Jegat C; Secheresse F Acidification of [WS,]*−. Synthesis and Structures of Di-p-suIfido-Bis[(2,2’-Bipyridine)Chlorooxotungsten(v)] and Di-p-Sulfido-Bis[(2,2’-Bipyridine)Bromooxotungsten(v)] t. J CHEM SOC DALTON TRANS 1994. [Google Scholar]
  • (40).Drew MGB; Hobson RJ; Rice DA; Turp N The Reaction of WS,CI, w i t h Pyridine: Crystal Structure of Di-p-Sulphido- Bis[Chlorobis(Pyridine)Sulphidotungsten(v)]-Pyridine (1/2),[W,S,CI,(Py),]2py.
  • (41).Groysman S; Holm RH Synthesis and Structures of Bis(Dithiolene)Tungsten(IV,VI) Thiolate and Selenolate Complexes: Approaches to the Active Sites of Molybdenum and Tungsten Formate Dehydrogenases. Inorg. Chem 2007, 46 (10), 4090–4102. 10.1021/ic062441a. [DOI] [PubMed] [Google Scholar]
  • (42).Goddard CA; Holm RH Synthesis and Reactivity Aspects of the Bis(Dithiolene) Chalcogenide Series [W IV Q(S 2 C 2 R 2) 2] 2- (Q = O, S, Se). Inorg. Chem 1999, 38 (23), 5389–5398. 10.1021/ic9903329. [DOI] [Google Scholar]
  • (43).Majumdar A; Mitra J; Pal K; Sarkar S Mono-Oxo Bis(Dithiolene) Mo(IV)/W(IV) Complexes as Building Blocks for Sulfide Bridged Bi- and Tri-Nuclear Complexes. Inorg. Chem 2008, 47 (12), 5360–5364. 10.1021/ic800466x. [DOI] [PubMed] [Google Scholar]
  • (44).Sung K-M; Holm RH Substitution and Oxidation Reactions of Bis(Dithiolene)Tungsten Complexes of Potential Relevance to Enzyme Sites. Inorg. Chem 2001, 40 (18), 4518–4525. 10.1021/ic010421x. [DOI] [PubMed] [Google Scholar]
  • (45).Bruce A; Corbin JL; Dahlstrom PL; Hyde JR; Minelli M; Stiefel EI; Spence JT; Zubieta J Investigations of the Coordination Chemistry of Molybdenum with Facultative Tetradentate Ligands Possessing N2S2 Donor Sets. 3. Crystal and Molecular Structures of [MoO2(SCH2CH2NMe(CH2)nNMeCH2CH2S)], n = 2 or 3, and [MoO2(SC6H4NHCH2CH2NHC6H4S)] and a Comparison to the Structure of [MoO2(SCH2CH2NHCH2CH2SCH2CH2S)], a Complex with the NS3 Donor Set. Inorg. Chem 1982, 21 (3), 917–926. 10.1021/ic00133a013. [DOI] [Google Scholar]
  • (46).Pangborn AB; Giardello MA; Grubbs RH; Rosen RK; Timmers FJ Safe and Convenient Procedure for Solvent Purification. Organometallics 1996, 15 (5), 1518–1520. 10.1021/om9503712. [DOI] [Google Scholar]
  • (47).Sheldrick GM A Short History of SHELX. Acta Crystallogr. A 2008, 64 (1), 112–122. 10.1107/S0108767307043930. [DOI] [PubMed] [Google Scholar]
  • (48).Müller P Practical Suggestions for Better Crystal Structures. Crystallogr. Rev 2009, 15 (1), 57–83. 10.1080/08893110802547240. [DOI] [Google Scholar]

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