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. Author manuscript; available in PMC: 2025 Jul 27.
Published in final edited form as: Inorg Chem. 2025 Jun 15;64(25):12651–12657. doi: 10.1021/acs.inorgchem.5c01261

Investigating Molybdenum and Tungsten Carbonyls as a Bridge Between Elemental Chalcogens and CO: Formation of COS and Selenium Complexes

Tobias J Sherbow 1, Haley M Smith 1, Keyan Li 1, Lev N Zakharov 1, Michael D Pluth 1,*
PMCID: PMC12292037  NIHMSID: NIHMS2095782  PMID: 40518625

Abstract

Carbonyl sulfide (COS) is hypothesized to play potential roles as a peptide coupling agent in prebiotic chemistry, and recent work harnessing the carbonic anhydrase mediated COS hydrolysis for H2S release has led to a resurgence of interest in COS-related chemistry. Building from the importance of metal chalcogenides in bioinorganic systems and potential of forming metal carbonyls under reducing environments, we investigated whether simple metal carbonyl compounds could be a source of COS or COSe when treated with elemental S or Se, respectively. Using the simple carbonyl compounds [TpMo(CO)3]− and [TpW(CO)3]−, we measured and quantified COS generation en route to [TpMo(S)(S4)]− and [TpW(S)3]− product formation, respectively. Highlighting the different reactivity of the selenium congener, analogous reactions with grey Se did not generate COSe. We found that [TpMo(CO)3]− was inert toward Se, and [TpW(CO)3]− reacted with Se to form the unusual triselenide bridged product [TpW(CO)2]2Se3, which was characterized by X-ray crystallography. Taken together, these results advance our understanding of the potential role of metal carbonyl compounds in the metal-mediated interconnectivity between CO and reactive sulfur and selenium species and further differentiate reactivity profiles between sulfur and selenium motifs at inorganic centers.

Graphical Abstract

graphic file with name nihms-2095782-f0005.jpg

[TpMo(CO)3]− and [TpW(CO)3]− react with elemental S8 to generate COS. [TpMo(CO)3]− is inert toward elemental Se, [TpW(CO)3]− reacts to generate triselenide-bridged [TpW(CO)2]2Se3.

Introduction

Metal chalcogenides play key roles in terrestrial chemistry and biology. Simple examples of this importance are found in common metal oxo motifs in metalloenzymes, ranging from the iron-based cytochrome P450 enzymes and methane monooxygenases to molybdenum-based sulfite oxidase and xanthine oxidase.1–2 Each of these systems carry out specific chemical reactions that harness high-energy M=O motifs and enable oxidations that would not occur with molecular oxygen alone. Moving down one row in the periodic table, sulfur also plays key roles in biology, particularly prior to the rise of appreciable atmospheric oxygen.3 The interplay between sulfur and metals is also apparent, with the low solubility of metal sulfides helping to potentiate the bioavailability of metals dissolved in oceans and other bodies of water.4 Similarly, sulfide lowers heavy metal ion toxicity in archaea native to hyperthermophilic vent environments, which were likely early locales capable of supporting life.5 These reducing environments devoid of oxygen but rich in sulfur provided a home for early chemolithoautotrophic and sulfur-reducing microorganisms that likely built the cornerstones of bioinorganic metal-chalcogen chemistry still found today in modern biology. Despite being a trace element in Nature, Se has cemented its role in biology with several enzymatic processes relying solely on Se rather than S for their activity. For example, Mo-containing metalloenzymes, such as formate dehydrogenase and nicotinate dehydrogenase, have incorporated Se for active site transformations due to the enhanced nucleophilicity and lower redox potential of Se over S.6–7

Under prebiotic conditions, carbon-containing sulfur compounds, such as carbonyl sulfide (COS), have also been hypothesized to play important roles in advancing molecular complexity. COS is the most prevalent sulfur-containing gas in Earth’s atmosphere and is often found at elevated concentrations near volcanoes and hot springs. In the presence of amino acids, COS can act as a coupling agent to form dipeptides, aminoacyl phosphates, and aminoacyl adenylates, all of which are important building blocks for early life.8–10 This potential prebiotic importance, coupled with a more reducing early-Earth environment that may have generated metal carbonyl motifs,11–12 prompted us to investigate the role of simple metal carbonyl compounds in COS generation. Furthermore, we also viewed this as a viable platform to investigate whether similar chemistry could be observed from the heavier chalcogen congener Se as a platform for carbonyl selenide (COSe) formation. Both of these approaches would provide new insights into the metal-mediated crosstalk between CO and reactive sulfur and selenium species and further investigate differences in sulfur and selenium reactivity at inorganic centers.

Results and Discussion

Inspired by the prevalence of reactive metal sulfide in xanthine oxidase enzymes, and also the importance of Mo and W in enzymes that catalyze highly kinetically challenging transformations,13–14 we wanted to investigate whether simple Mo and W carbonyl compounds could serve as potential precursors to COS formation. Hidai and coworkers previously studied the reactivity of zero valent [TpMo(CO)3]− and [TpW(CO)3]− and demonstrated that reaction of these complexes with elemental sulfur (S8) resulted in the formation of [TpMo(S)(S4)]− and [TpW(S)3]−, respectively.15 The other products of this reaction were not characterized. The formation of the [TpMo(S)(S4)]− product is the result of a 4e− oxidation at the Mo metal center in [TpMo(CO)3]− to reduce one S0 equivalent to a terminal sulfide (S2−) ligand and to reduce a S4 moiety by 2e− to form a tetrasulfide (S42−) ligand. More recently using the same ligand platform, we demonstrated that introducing more reducing equivalents, either in the form HS− or PPh3, resulted in tandem oxidation of the Mo4+ to Mo6+ to form the tris(sulfide) [TpMo(S)3]− product.16 In contrast, the formation of [TpW(S)3]− proceeds rapidly from the 6e− oxidation of [TpW(CO)3]− to reduce three S0 equivalents to form the three terminal S2− sulfide ligands in [TpW(S)3]−. Taken together, these results suggest that [TpW(CO)3]− has greater reducing power than [TpMo(CO)3]−, and that these two compounds could provide useful models to probe COS formation from M-CO motifs based on the well-defined metal sulfide products.

To investigate the details of these reactions more closely, we monitored the reactions [TpMo(CO)3]− and [TpW(CO)3]− with S8 in sealed NMR tubes. Treatment of [TpMo(CO)3]− with 1.0 equiv of S8 in THF-d8 at 50 °C for 16 h resulted in a color change from light yellow to dark green. Both the color change and the resultant 1H NMR spectrum of the product was consistent with formation of [TpMo(S)(S4)]− as expected. The analogous reaction was also performed with the W congener by treating [TpW(CO)3]− with 1.0 equiv of S8 in THF-d8 at 50 °C for 16 h. Under these conditions, the reaction mixture turned from yellow to dark red, and the color change along with the resultant 1H NMR spectrum was consistent with the formation of [TpW(S)3]−. To probe the fate of the CO ligands, we also monitored the 13C{1H} NMR spectra of both reactions (Figure 1). Although ligand substitution reactions in metal carbonyl compounds often release CO when thermally or photochemically activated, we did not observe free CO in either reaction by 13C{1H} NMR spectroscopy (expected: δ = 185.2 ppm). Instead, we observed a new resonance at 154.4 ppm in both reactions, which matched the chemical shift of independently synthesized COS in THF-d8.17 No other carbonyl-containing compounds were observed, which suggested that CO ligands are either dissociated in low amounts or underwent two-electron oxidation to COS.

Figure 1.

Figure 1.

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(a) Reaction scheme of (a) [TpMo(CO)3]− + S8 and 13C{1H} NMR spectrum (THF-d8) of the sealed tube reaction products showing COS formation at δ = 154.3 ppm. (b) Reaction scheme of [TpW(CO)3]− + S8 and 13C{1H} NMR spectrum (THF-d8) of the sealed tube reaction products showing COS formation at δ = 154.3 ppm.

To further probe the stoichiometry of COS formed from these reactions, we repeated the reactions between [TpM(CO)3]− (M = W, Mo) and 1 equiv. of S8 and analyzed the reaction yields of [TpW(S)3]− and [TpMoS(S4)]− by 1H NMR spectroscopy. Direct COS measurement and quantification is difficult due to the low sensitivity of COS on common gas chromatograph (GC) detectors, but we were able to quantify COS directly using a pulsed flame photometric detector (PFPD) GC system. Upon stirring 1.0 mM [TpM(CO)3]− and S8 in THF for 18 hours, quantitative 1H NMR analyses revealed yields of 51% and 48% for [TpW(S)3]− and [TpMoS(S4)]−, respectively. GC headspace analyses, quantified against a calibration curve with analytical standards of COS, revealed COS concentrations of 0.99 (± 0.19) mM and 0.95 (± 0.05) mM for the W- and Mo-containing reaction mixtures, respectively. These data support that each equivalent of [TpW(S)3]− or [TpMoS(S4)]− formation is accompanied by of the generation of 2 equiv of COS.

Based on these results and the known lability of CO ligands of [TpM0(CO)3]− under mildly oxidizing conditions,18–19 we propose that [TpM0(CO)3]− complex likely dissociates one CO ligand prior to reduction of sulfane sulfur (S0) from S8 by two-electrons to form a reactive M2+=S fragment. Given that metal sulfido species have been previously been shown to activate CO, we hypothesize that this metal sulfido intermediate can then undergo facile migratory insertion to CO followed by reductive elimination to extrude COS and regenerate the M0-containing species.20–21 Further CO oxidation in the presence of S0 through similar pathway generates a second equivalent of COS and eventual formation of [TpW6+(S)3]− or [TpMo4+S(S4)]− through direct S-centered reduction (Scheme 1). Analogous reactivity has been reported by Nicholas and co-workers, in which (MeCp)2Nb3+(CO)CH2Si(CH3)3 reacts with S8 to form (MeCp)2Nb5+(η2-COS)CH2Si-(CH3)3,22 with analogous chemistry also being reported for Ta3+.20 Although we were unable to directly characterize intermediates formed from the reaction between [TpW0(CO)3]− and S8 due to the rapid nature of the reaction, we were able to observe although not isolate intermediates formed from the reaction between [TpMo0(CO)3]− and S8 by both 1H NMR and IR spectroscopy (Figures S6, S10). In particular, the IR spectrum from the crude reaction mixture between [TpMo0(CO)3]− and S8 revealed the loss of characteristic ν(C–O) features corresponding to [TpMo0(CO)3]− (1877 cm−1 and 1731 cm−1) and growth of new ν(C–O) features at 2037 cm−1 and 1785 cm−1 (Figure S8), which is consistent with formation of [TpMo2+(CO)2X]− species (Figure S9).18, 23 To understand whether formation of 2 equiv. of COS is required for product formation, we treated [TpM0(CO)3]− complexes with stoichiometric amounts of S0 (3 equiv. S0 for W; 5 equiv. S0 for Mo) and observed little to no formation of [TpW(S)3]− and [TpMoS(S4)]− by 1H NMR spectroscopy, which further supports our hypothesis that the excess S0 required for these reactions as also seen in work by Hidai and co-workers are due to the essential extrusion of COS.

Scheme 1.

Scheme 1.

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Proposed CO and COS stoichiometry based on GC headspace measurement.

The observed COS extrusion from both the Mo and W complexes is consistent with prior work by Sita and coworkers, which demonstrated photocatalytic S atom transfer reactions to CO to form COS from Cp*Mo{N(iPr)-C(Ph)N(iPr)}(CO)S2 in the presence of excess S8 and CO.24 To test for similar potential turnover, we treated isolated [TpMo(S)(S4)]− and [TpW(S)3]− with excess CO, but failed to observe any formation of M(CO)x products by 13C{1H} NMR spectroscopy. This lack of reactivity is not unexpected since both [TpMo(S)(S4)]− and [TpW(S)3]− are already coordinatively saturated at the metal center. Furthermore, this is in agreement with the high valency of W6+ in [TpW(S)3]−, which does not allow for further W oxidation to help facilitate the activation and reactivity with CO and S8.

Having established that [TpMo(CO)3]− and [TpW(CO)3]− react with S8 to generate COS, we were also curious whether analogous reactivity would be observed with elemental Se to generate COSe. When compared to COS, the fundamental chemistry of COSe is much less investigated, with prior work primarily focusing on preparation,25–26 carbonylation of amines,27–28 and other related carbonylation reactions.29 Treatment of [TpMo(CO)3]− with 1 equiv. of gray Se in THF-d8 in a sealed NMR tube at 50 °C for 16 h failed to produce any observable reaction. Similarly, extended heating at 50 °C for up to 3 days did not result in any changes in the 1H NMR spectrum of [TpMo(CO)3]−. By contrast, treatment of [TpW(CO)3]− with Se under identical conditions resulted in a color change from black to deep green. Analysis of the 1H NMR spectrum showed loss of C3 symmetry and formation of new resonances consistent with a C2 symmetric product (Figure 2), which was later identified as a bridged triselenide (vide infra) rather than a metal selenido species as seen from the reactivity of [TpW(CO)3]− toward S8. Analysis of the 13C{1H} NMR spectrum showed the formation of new peaks corresponding to the W-containing product, a peak for free CO at 185 ppm, but no new resonances for COSe were observed (expected chemical shift: 156.6 ppm).30 We note that the lack of reaction between [TpMo(CO)3]− and Se is consistent with previous results suggesting that [TpMo(CO)3]− is a weaker reductant than [TpW(CO)3]−. More broadly, this differential reactivity between S8 and Se toward these simple metal carbonyl complexes highlights the significant differences in S and Se activation my inorganic centers.

Figure 2.

Figure 2.

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(a) Reaction of [TpMo(CO)3]− with Se. (b) 1H NMR spectrum of the reaction product showing change from C3 to C2 symmetry. * = THF solvent resonances; # = NBu4+ resonances. (c) Solid-state structure of [TpW(CO)2]2Se3. Ellipsoids are shown at 50% probability levels. Blue, red, orange, pink, and green ellipsoids represent N, O, Se, B, and W atoms, respectively. A residual toluene molecule and all the C-H bonds are omitted for clarity.

To further investigate the identity of the product, we scaled up the reaction by treating [NBu4][TpW(CO)3] with excess gray Se powder at 80 °C for 16 hours in THF in a sealed tube under N2. Filtration of the dark green reaction mixture through Celite and removal of the THF under vacuum afforded a green powder, which was recrystallized from a toluene solution layered with hexanes to yield crystals suitable for X-ray diffraction. Crystallographic analysis revealed that the structure was triselenide bridged [TpW(CO)2]2Se3, which is thermally unstable and slowly decomposes under prolonged storing, even at −30 °C in the dark under anaerobic conditions. Further structural analysis show [TpW(CO)2]2Se3 was crystallized in C2/c with the central Se atom in the triselenide sitting on a 2-fold rotational axis. The W-Se-Se-Se dihedral (166.3°) deviates from complete co-planarity, and the W-Se-Se angle is 102.09(2)°. In the trisulfide, the W-Se and Se-Se bond distances are 2.3942(6) and 2.3607(7) Å, respectively. The NMR spectrum of isolated crystals of [TpW(CO)2]2Se3 matches that of the bulk material. To the best of our knowledge, [CpW(CO)3]2Se3 is the only other crystallographically characterized compounds with an isolated W-Se3-W motif.31 [CpW(CO)3]2Se3 was prepared by treatment of [CpW(CO)3][Li] with gray Se and has W-Se bond distances of 2.651(2) and 2.632(1) Å and Se-Se bond distances of 2.348(2) and 2.342(2) Å. The significantly shorter W-Se bond distances in [TpW(CO)2]2Se3 are consistent with the different coordination environment of the [CpW(CO)3]+ and [TpW(CO)2]+ fragments. Formation of [TpW(CO)2]2Se3 rather than COSe extrusion in the above example also supports the hypothesis that carbonyl chalcogenide formation stems from intermediate metal chalcogenido species, as seen in the reaction between S8 and [TpM(CO)3]− (M = Mo, W), rather than the from the parent carbonyl precursors directly.

Based on the relatively unusual structure of [TpW(CO)2]2Se3 and rarity of polyselenide bridged species, we next sought to investigate its basic reactivity with simple reductants and nucleophiles. Treatment of [TpW(CO)2]2Se3 with 1 equiv. of PPh3 resulted in rapid and stoichiometric formation of a new peak in the 31P{1H} NMR spectrum corresponding to Ph3P=Se (35.4 ppm) and decomposition of the resultant [TpW(CO)2Se] fragment into an intractable product mixture (Figure 3). Treatment of [TpW(CO)2]2Se3 with nucleophilic BnSK resulted in rapid formation of a blue solution, which gradually bleached to green and then finally to a red/brown color. We attribute the formation of these highly colored compounds to the transient formation of polyselenide anions generated from triselenide cleavage by BnS− and subsequent reduction. Treatment of the resultant reaction mixture with BnBr resulted in Bn2Se formation as evidenced by the major peak at 335.1 ppm in the 77Se NMR spectrum, which matched the chemical shift of authentic Bn2Se.32 Alternatively, treatment of the reaction mixture with PPh3 resulted in Ph3P=Se formation. Taken together, these trapping experiments support that both Se0 and Se2− species are present, which is consistent with polyselenide formation. Isolation of the W-containing product after treatment with BnSK revealed formation of TpW(CO)2(SBn), as evidenced by NMR spectroscopy and X-ray crystallography. TpW(CO)2(SBn) is a known compound that was prepared previously by treatment of TpW(CO)2I with BnSH, and the NMR spectrum matches the previously reported spectrum.33 Formation of this thiolate adduct suggests that either the triselenide bridge is labile, which would also help explain the thermal instability of this compound, or that attack of the BnS− on the W-Se motif generates an unstable TpW(CO)2(SeSBn) intermediate that extrudes Se to form the more thermodynamically stable TpW(CO)2(SBn) product.

Figure 3.

Figure 3.

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Summary of the reactivity of [TpW(CO)2]2Se3 with PPh3 and BnSK. The solid-state structure of TpW(CO)2(SBn) includes ellipsoids at 50% probability levels. Blue, red, yellow, pink, and light blue ellipsoids represent N, O, Se, B, and W atoms, respectively.

Conclusions

We have demonstrated that simple Mo and W carbonyl compounds can react with elemental sulfur to generate COS. The atom economical nature of this chemistry, in which CO and S8 are coupled to form COS, provides an intriguing reaction platform from which prebiotic precursors like COS can be generated from simple metal carbonyl compounds. Similar reactions of the Mo and W carbonyl compounds with elemental grey selenium did not generate COSe. [TpMo(CO)3]− was inert toward Se, whereas [TpW(CO)3]− reacted with Se to form the unusual [TpW(CO)2]2Se3 product, which was characterized by X-ray crystallography. Basic reactivity studies show that the triselenide bridge can be cleaved by both reductants and nucleophiles. More broadly, this work advances our understanding of the potential routes of metal-mediated interconnectivity between CO and reactive sulfur and selenium species. These results also expand the fundamental differences in observed S and Se chemistry at metal centers and highlight pathways in which COS generation could be possible from simple inorganic motifs.

Experimental Section

Materials and Methods.

All manipulations were performed under an inert atmosphere using an Innovative Technology N2-filled glove box unless otherwise noted. C6D6 was degassed with N2 and stored in an inert atmosphere glove box over 4 Å molecular sieves. THF-d8 was degassed with N2, distilled from Na/benzophenone, and stored in an inert atmosphere glove box over 4 Å molecular sieves. All commercially available chemicals were used as received and purchased from Strem. [NBu4][TpMo(CO)3],34 [NBu4][TpW(CO)3],34 BnSK,35 and COS17 were synthesized from established procedures. C6D6 and THF-d8 were purchased from Cambridge Isotope Laboratories. COS standards in toluene were purchased from AccuStandard. UV/Vis spectra were acquired on an Agilent Cary 60 UV/Vis spectrophotometer equipped with a Quantum Northwest TC-1 temperature controller set at 25.0 ± 0.05 °C. NMR spectra were acquired on a Varian 500 MHz spectrometer (1H: 500 MHz, 13C: 126 MHz, 31P: 202 MHz, 77Se: 95 MHz ). Chemical shifts are reported in parts per million (δ) and are referenced to an internal or external standard (PPh3 for 31P, δ = −6.00 ppm). IR spectra were acquired on a Nicolet 6700 IR Spectrometer as ATR or KBr pellet samples. COS was quantified using an Agilent 8890 GC system with a DB-FFAP column (60 m x 0.250 mm, 0.25 μM) and a 5383 PFPD from OI Analytical. The injector was used in split mode with a split ratio of 10:1 at 250 °C. Nitrogen was used as the carrier gas at 2 mL/min with an oven temperature program of 0-1 min 40 °C, increase to 120 °C at a rate of 10 °C/min from 1-9 min, hold at 120 °C from 9-10 min. For typical experiments, the COS peak eluted at 3.1-3.2 min.

X-Ray Crystallography.

Diffraction intensities for [TpW(CO)2]2Se3 and TpW(CO)2(SBn) were collected at 173 K on a Bruker Apex2 CCD diffractometer using an Incoatec Cu IμS source with CuK⟨ radiation (1.54178 Å). The space groups were determined based on systematic absences and intensity statistics. Absorption corrections were applied by SADABS.36 Structures were solved by direct methods and Fourier techniques and refined on F2 using full matrix least-squares procedures. All non-H atoms were refined with anisotropic thermal parameters. H atoms in both structures were refined in calculated positions in a rigid group model, except the H atoms at the B atoms which were found on the residual density map and refined with isotropic thermal parameters. Both structures include solvent molecules: toluene in [TpW(CO)2]2Se3 and tetrahydrofuran in TpW(CO)2(SBn). All calculations were performed using the Bruker SHELXL-2014/7 package.37

COS generation from [NBu4][TpMo(CO)3].

A J-young NMR tube was charged with [NBu4][TpMo(CO)3] (0.020 g, 0.029 mmol), S8 (0.010 g, 0.31 mmol “S0”) and 0.5 mL THF-d8. The Teflon screw top was closed on the J-young NMR tube, and the solution was heated at 50 °C on a hot plate in a heating container containing metal beads for 24 hrs. The solution turned from a yellow color to a dark green color over this time, and the reaction was analyzed by 1H and 13C{1H} NMR spectroscopy. As previously described, the [NBu4][TpMo(S)(S4)] product formed, and the spectral data matched previously reported data for [NBu4][TpMo(S)(S4)]. The 13C{1H} NMR spectrum was analyzed to determine the CO-containing by products of the reaction. A peak at 154.5 ppm was observed, corresponding to COS.

COS generation from [NBu4][TpW(CO)3].

A J-young NMR tube was charged with [NBu4][TpW(CO)3] (0.0249 g, 0.031 mmol), S8 (0.0088 g, 0.275 mmol “S0”), and 0.5 mL THF-d8. The Teflon screw top was closed on the J-young NMR tube, and the solution was heated at 50 °C on a hot plate with a container containing metal beads for 24 hrs. The solution immediately began changing color from yellow to a dark red. The reaction was analyzed by 1H and 13C{1H} NMR spectroscopy. As previously described, the [NBu4][TpW(S)3] product was formed, and the spectral data matched previously reported data for [NBu4][TpW(S)3]. The 13C{1H} NMR spectrum was analyzed to determine the CO containing by products. A peak at 154.5 ppm was observed, corresponding to COS.

General procedures COS calibration curves.

Individual stock solutions of COS (0.5, 1.0, 2.0, 3.0, and 4.0 mM) were prepared in THF (180 μL) in 20 mL septum sealed scintillation vials using known COS concentrations from an analytical sample in toluene (34.5 mM). After equilibration, a sample of the headspace (5 μL) from each individual stock solution was removed an analyzed by GC to generate a calibration curve for COS (Figure S10).

General procedures for COS quantification.

A 150 μL aliquot of a stock solution of a 1.0 mM solution of [Tp*M(CO)3][NBu4] (M: W, Mo) in THF was added to three separate septum-capped 20 mL scintillation vials equipped with stir bars, after which 1 equiv. of S8 from a 50 mM stock solution in THF was added. The reaction mixtures were allowed to stir for 18 h before headspace samples (5 μL) were removed and analyzed by GC. (Avg yield of COS for W: 0.99 mM ± 0.19, Avg yield of COS for Mo: 0.95 mM ± 0.05).

General procedures for quantification of [Tp*WS3][NBu4] and [Tp*MoS(S4)][NBu4] formation.

To match the general conditions for GC measurements of COS, stock solutions of [Tp*M(CO)3][NBu4] (M: W, Mo) in THF (1 mM, 600 μL) containing known amounts of hexamethylbenzene as an internal standard were added to 20 mL scintillations vial equipped with stir bar before another stock solution of S8 in THF (50 mM, 1 equiv.) was added to the sample. The reaction was stirred for 18 h, after which all volatiles were removed under vacuum before analysis by 1H NMR spectroscopy in C6D6, revealing a 51% yield for [Tp*WS3][NBu4] and a 48% yield for [Tp*MoS(S4)][NBu4] by integration with respect to hexamethylbenzene.

Synthesis of [TpW(CO)2]2Se3.

In the glovebox, a Schlenk tube with a Teflon screw top was charged with [NBu4][TpW(CO)3] (0.104 g, 0.128 mmol), excess grey Se powder (0.136 g, 1.72 mmol), and 5 mL of THF to form a black slurry. The Schlenk tube was closed and heated at 80 °C on a hot plate with metal beads for 16 hours, during which the black slurry turned a deep green color. The slurry was filtered over a pad of Celite, and solvent from the resulting green filtrate was removed in vacuo to yield [TpW(CO)2]2Se3 (48.0 mg, 57% yield) as a powder. Green crystals suitable for X-ray diffraction studies were grown from a concentrated toluene solution that was layered with hexanes and stored overnight at room temperature. [TpW(CO)2]2Se3 is thermally unstable and decomposes at room temperature, even under an inert atmosphere. 1H NMR (600 MHz, C6D6) δ: 5.59 (s, 2H), 5.33 (s, 1H), 2.52 (s, 6H), 2.41 (s, 3H), 1.90 (s, 3H), 1.81 (s, 6H). 13C{1H} NMR (151 MHz, C6D6) δ: 244.8, 159.0, 150.4, 147.1, 144.2, 109.2, 106.6, 17.6, 16.3, 12.4, 12.2. UV-vis spectrum (THF) λmax (εM, M−1cm−1): 328 (25,670), 327 (25,800), 594 (8,340). FTIR (KBr, cm−1): 2545 (w, νB-H), 1942 (sh, νCO), 1918 (s, νCO), 1842 (s, νCO).

Reaction of [TpW(CO)2]2Se3 with PPh3.

[TpW(CO)2]2Se3 (0.0030 g, 0.0023 mmol) was dissolved in 0.5 mL of C6D6 in an NMR tube. To this solution was added 11 μL of a 0.199 M PPh3 solution in C6D6. Upon addition of the PPh3 solution, a purple-red precipitate formed, and a 31P NMR spectrum was acquired. The NMR spectrum revealed formation of Ph3P=Se at −34.7 ppm.

Reaction of [TpW(CO)2]2Se3 with BnSK to form TpW(CO)2SBn.

A scintillation vial was charged with [TpW(CO)2]2Se3 (0.010 g, 0.0076 mmol) and 3 equiv. of BnSK (0.0040 g, 0.025 mmol). THF (5 mL) was added to the vial, and the resultant mixture was stirred. The solution turned from dark green to bright blue within seconds, and the blue color dissipated over the next hour to afford a yellow-brown solution. The solution was filtered over a pad of Celite, concentrated under vacuum, layered with hexanes, and placed in the freezer at −25 °C. Yellow crystals formed overnight and were analyzed by single crystal X-ray diffraction revealing the formation of TpW(CO)2SBn. The crystals were further analyzed by 1H NMR and IR spectroscopy, and the resultant spectral data matched those previously reported for TpW(CO)2(SBn).33

Reaction of [TpW(CO)2]2Se3 with BnSK in the presence of BnBr.

A scintillation vial was charged with [TpW(CO)2]2Se3 (0.008 g, 0.006 mmol), BnSK (0.0040 g, 0.025 mmol), and excess BnBr (0.012 g, 0.071 mmol). THF (5 mL) was added to the vial, and the resultant reaction mixture was stirred. The solution quickly turned color from dark green to yellow. The solution was filtered, the solvent was removed under reduced pressure, and the residue was analyzed by 1H and 77Se NMR spectroscopy. The 1H NMR spectrum revealed the formation of TpW(CO)2(SBn) and Bn2(Se)n products. The 77Se NMR spectrum agreed with the Se containing product being Bn2Se observed at 335.1 ppm.32

Supplementary Material

supporting information

The following files are available free of charge. X-Ray crystallography data, NMR spectra, IR spectra, and UV-Vis spectra. (PDF)

ACKNOWLEDGMENT

We thank the NIH (F32-GM139372 to T.J.S; R01-GM113030 to M.D.P.) for support of this research. A prior version of this manuscript was published as ChemRxiv preprint.38

References

  • 1.Hille R; Hall J; Basu P, The Mononuclear Molybdenum Enzymes. Chem. Rev 2014, 114 (7), 3963–4038. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 2.Liu J; Chakraborty S; Hosseinzadeh P; Yu Y; Tian SL; Petrik I; Bhagi A; Lu Y, Metalloproteins Containing Cytochrome, Iron-Sulfur, or Copper Redox Centers. Chem. Rev 2014, 114 (8), 4366–4469. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 3.Olson KR; Straub KD, The Role of Hydrogen Sulfide in Evolution and the Evolution of Hydrogen Sulfide in Metabolism and Signaling. Physiology 2016, 31 (1), 60–72. [DOI] [PubMed] [Google Scholar]
  • 4.Saito MA; Sigman DM; Morel FMM, The bioinorganic chemistry of the ancient ocean: the co-evolution of cyanobacterial metal requirements and biogeochemical cycles at the Archean-Proterozoic boundary? Inorg. Chem. Acta 2003, 356, 308–318. [Google Scholar]
  • 5.Edgcomb VP; Molyneaux SJ; Saito MA; Lloyd K; Boer S; Wirsen CO; Atkins MS; Teske A, Sulfide ameliorates metal toxicity for deep-sea hydrothermal vent archaea. Appl. Environ. Microbiol 2004, 70 (4), 2551–2555. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 6.Khangulov SV; Gladyshev VN; Dismukes GC; Stadtman TC, Selenium-Containing Formate Dehydrogenase H from Escherichia coli: A Molybdopterin Enzyme That Catalyzes Formate Oxidation without Oxygen Transfer. Biochemistry 1998, 37 (10), 3518–3528. [DOI] [PubMed] [Google Scholar]
  • 7.Reich HJ; Hondal RJ, Why Nature Chose Selenium. ACS Chem. Biol 2016, 11 (4), 821–841. [DOI] [PubMed] [Google Scholar]
  • 8.Leman L; Orgel L; Ghadiri MR, Carbonyl sulfide-mediated prebiotic formation of peptides. Science 2004, 306 (5694), 283–286. [DOI] [PubMed] [Google Scholar]
  • 9.Leman LJ; Orgel LE; Ghadiri MR, Amino acid dependent formation of phosphate anhydrides in water mediated by carbonyl sulfide. J. Am. Chem. Soc 2006, 128 (1), 20–21. [DOI] [PubMed] [Google Scholar]
  • 10.Steiger AK; Zhao Y; Pluth MD, Emerging Roles of Carbonyl Sulfide in Chemical Biology: Sulfide Transporter or Gasotransmitter? Antioxid. Redox Signal 2018, 28 (16), 1516–1532. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 11.Cody GD; Boctor NZ; Filley TR; Hazen RM; Scott JH; Sharma A; Yoder HS, Primordial carbonylated iron-sulfur compounds and the synthesis of pyruvate. Science 2000, 289 (5483), 1337–1340. [DOI] [PubMed] [Google Scholar]
  • 12.Miyakawa S; Yamanashi H; Kobayashi K; Cleaves HJ; Miller SL, Prebiotic synthesis from CO atmospheres: Implications for the origins of life. Proc. Natl. Acad. Sci. USA 2002, 99 (23), 14628–14631. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 13.Dobbek H; Gremer L; Kiefersauer R; Huber R; Meyer O, Catalysis at a dinuclear [CuSMo(O)OH] cluster in a CO dehydrogenase resolved at 1.1-A resolution. Proc. Natl. Acad. Sci 2002, 99 (25), 15971–15976. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 14.Rothery RA; Workun GJ; Weiner JH, The prokaryotic complex iron-sulfur molybdoenzyme family. Biochim. Biophys. Acta Biomembr 2008, 1778 (9), 1897–1929. [DOI] [PubMed] [Google Scholar]
  • 15.Seino H; Arai Y; Iwata N; Nagao S; Mizobe Y; Hidai M, Preparation of mononuclear tungsten tris(sulfido) and molybdenum sulfido-tetrasulfido complexes with hydridotris(pyrazolyl)borate coligand and conversion of the former into sulfido-bridged bimetallic complex having Pt(μ-S)2WS core. Inorg. Chem 2001, 40 (7), 1677–1682. [DOI] [PubMed] [Google Scholar]
  • 16.Sherbow TJ; Zakharov LN; Johnson DW; Pluth MD, Hydrosulfide Oxidation at a Molybdenum Tetrasulfido Complex. Inorg. Chem 2020, 59 (21), 15574–15578. [DOI] [PubMed] [Google Scholar]
  • 17.Cerda MM; Fehr JM; Sherbow TJ; Pluth MD, Progress toward colorimetric and fluorescent detection of carbonyl sulfide. Chem. Commun 2020, 56 (67), 9644–9647. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 18.Seidel WW; Ibarra Arias MD; Schaffrath M; Jahnke MC; Hepp A; Pape T, Molybdenum and Tungsten η2-Alkyne-1-thio Complexes Acting as Sulfur Donors in Homoleptic Werner Type Complexes with Nickel(II) and Palladium(II). Inorg. Chem 2006, 45 (12), 4791–4800. [DOI] [PubMed] [Google Scholar]
  • 19.Young CG; Malarek MS; Evans DJ; Doonan CJ; Ng VWL; White JM, Synthesis and Characterization of TpiPrMoO(S2PR2) (R = Pri, Ph, OEt, OPri, (−)-Mentholate) and {HB(OMe)(Pripz)2}MoO(S2PPri2), Including Isomers of Known 1,2-Borotropically-Shifted Complexes. Inorg. Chem 2009, 48 (5), 1960–1966. [DOI] [PubMed] [Google Scholar]
  • 20.Winkler U; Khan MA; Nicholas KM, Atom addition and insertion reactions of (MeCp)2Ta(H)CO with sulfur, tellurium, carbonyl sulfide and carbon disulfide. Inorg. Chem. Commun 1998, 1 (8), 317–319. [Google Scholar]
  • 21.Hartmann NJ; Wu G; Hayton TW, Reactivity of a Nickel Sulfide with Carbon Monoxide and Nitric Oxide. J. Am. Chem. Soc 2016, 138 (38), 12352–12355. [DOI] [PubMed] [Google Scholar]
  • 22.Fu PF; Khan MA; Nicholas KM, Facile transformation of a metal carbonyl to a metal carbonyl sulfide by reaction with elemental sulfur. Organometallics 1993, 12 (10), 3790–3791. [Google Scholar]
  • 23.Nagao S; Seino H; Hidai M; Mizobe Y, Synthesis and X-ray structure of the new Mo diselenido complex with hydrotris(pyrazolyl)borate coligand [Et4N][TpMo(CO)2(η2-Se2)]. Inorg. Chem. Acta 2004, 357 (15), 4618–4621. [Google Scholar]
  • 24.Farrell WS; Zavalij PY; Sita LR, Metal-Catalyzed “On-Demand” Production of Carbonyl Sulfide from Carbon Monoxide and Elemental Sulfur. Angew. Chem. Int. Ed 2015, 54 (14), 4269–4273. [DOI] [PubMed] [Google Scholar]
  • 25.Kondo K; Yokoyama S; Miyoshi N; Murai S; Sonoda N, A New Synthesis of Carbonyl Selenide. Angew. Chem. Int. Ed. Engl 1979, 18 (9), 691–691. [Google Scholar]
  • 26.Pearson TG; Robinson PL, 83. Carbonyl selenide. Part I. Preparation and physical properties. J. Chem. Soc 1932, (0), 652–660. [Google Scholar]
  • 27.Kondo K; Yokoyama S; Miyoshi N; Murai S; Sonoda N, Reactions of Carbonyl Selenide with Amines and Aminoalcohols to Produce Ureas and Carbamates. Angew. Chem. Int. Ed. Engl 1979, 18 (9), 692–692. [Google Scholar]
  • 28.Zhang XP; Tang ZJ; Niu XL; Li ZW; Fan XS; Zhang GS, Selenium-catalyzed carbonylation of 2-aminothiazole with nitro aromatics to N-aryl-N’-2-thiazolylureas. Tetrahedron Lett. 2016, 57 (47), 5266–5270. [Google Scholar]
  • 29.Sonoda N, Selenium Assisted Carbonylation with Carbon-Monoxide. Pure Appl. Chem 1993, 65 (4), 699–706. [Google Scholar]
  • 30.Gombler W, NMR-spektroskopische Untersuchungen an Chalkogenyerbindungen, III 77Se− und 18O-NMR-Daten von Verbindungen mit C=S- und C—Se-Doppelbindung. Z. Naturforsch. B 1981, 36 (12), 1561–1565. [Google Scholar]
  • 31.Jones PG; Laube J; Thone C, Organometallic selenolates, 8 - The reaction of potassium polyselenides with CpW(CO)3Cl in DMF - Formation and crystal structure of CpW(CO)3SeC(O)NMe2 and {[CpW(CO)3]2Se4}. Eur. J. Inorg. Chem 1998, (3), 397–400. [Google Scholar]
  • 32.Newton TD; Pluth MD, Development of a hydrolysis-based small-molecule hydrogen selenide (H2Se) donor. Chem. Sci 2019, 10 (46), 10723–10727. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 33.Philipp CC; Young CG; White PS; Templeton JL, Dicarbonyltungsten(II) Thiolate Complexes of Hydridotris(3,5-dimethylpyrazolyl)borate. Inorg. Chem 1993, 32 (24), 5437–5443. [Google Scholar]
  • 34.Trofimenko S, Transition Metal Polypyrazolylborates Containing Other Ligands. J. Am. Chem. Soc 1969, 91 (3), 588–595. [Google Scholar]
  • 35.Gray VJ; Cuthbertson J; Wilden JD, Transition-Metal-Free Synthesis of Ynol Ethers and Thioynol Ethers via Displacement at sp Centers: A Revised Mechanistic Pathway. J. Org. Chem 2014, 79 (12), 5869–5874. [DOI] [PubMed] [Google Scholar]
  • 36.Sheldrick G, SADABS v. 2.01, Bruker/Siemens area detector absorption correction program. Bruker AXS, Madison, Wisconsin, USA: 1998. [Google Scholar]
  • 37.Sheldrick G, SHELXT - Integrated space-group and crystal-structure determination. Acta Crystallogr A 2015, 71 (1), 3–8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 38.Sherbow T; Li K; Zakharov L; Pluth M, Molybdenum and Tungsten Carbonyl Compounds Generate Carbonyl Sulfide (COS), but not Carbonyl Selenide (COSe), when Treated with Elemental Sulfur and Selenium. ChemRxiv (February/8/2023), DOI: 10.26434/chemrxiv-2023-hp0mt (accessed 2025-06-01). . [DOI]

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