Investigating Molybdenum and Tungsten Carbonyls as a Bridge between Elemental Chalcogens and CO: Formation of Carbonyl Sulfide and Selenium Complexes

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 the 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 gray 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 the inorganic centers.