Stepwise metal-promoted conversion of η2-CS2 into η2-SO. Synthesis and crystal structure of the complex [(triphos)Rh(µ-SO)2Rh(triphos)][BPh4]2·HCONMe2[triphos = MeC(CH2PPh2)3]

Abstract

Nucleophilic attack by PEt₃ at the carbon atom of the η²-CS₂ ligand in (tirphos)RhCl(η-²-CS₂)[triphos = MeC(CH₂PPh₂)₃] yields the η¹-phosphoniodithiocarboxylate complex (triphos)RhCl(S₂CPEt₃), which reacts with dioxygen to give the η²-dithiocarbonate complex (triphos)RhCl(S₂CO), treatment of which with NaBPh₄ gives [(triphos)Rh(S₂CO)]BPh₄; reaction of the latter with O₂ generates the novel µ-SO complex [(triphos)Rh(µ-SO)₂Rh(triphos)][BPh₄]₂·HCONMe₂, X-ray analysis of which shows that each bridging SO molecule is η²-bonded to one metal centre via O and S, and η¹-bonded to the other metal via S.