Binuclear cyclopentadienylvanadium carbonyl thiocarbonyls: Vanadium-vanadium bonding and four-electron donor bridging thiocarbonyl groups

► Density functional theory studies on the cyclopentadienylvanadium carbonyl thiocarbonyls Cp2V2(CS)2(CO)n (n = 5, 4, 3, 2, 1, 0) indicate the energetic preference for structures with four-electron donor bridging CS groups. ► The lowest energy Cp2V2(CS)2(CO)5 structures have an “end-on” four-electron donor CE (E = O, S) bridge and no vanadium-vanadium bond. ► Cp2V2(CS)2(CO)3 is predicted to lie energetically above the disproportionation products Cp2V2(CS)2(CO)4 + Cp2V2(CS)2(CO)2 in contrast to the stable carbonyl analog Cp2V2(CO)5 known experimentally. ► The thermodynamics of the Cp2V2(CS)2(CO)n system suggest Cp2V2(CS)2(CO)2 to be the most promising synthetic objective.