Dimetalla-heterocyclic carbenes: The interconversion of chalcocarbonyl and carbido ligands

The l-carbido complexes [Rh2(l-C)Cl2(PPh3)4] and [Rh2(l-C)Cl2(dppm)2] cleave CS2 to afford themonothiocarbonyl complexes [RhCl(CS)(PPh3)2] and [Rh2(l-CS)Cl2(dppm)2]. The latter reacts with dimethyl acetylenedicarboxylate (DMAD) to afford [Rh(l-CS)(l-DMAD)Cl2(dppm)2]. This complex is also formed from [Rh(l-C)(l-DMAD)Cl2(dppm)2] and sulfur. These strategies also afford the first rhodium selenocarbonyl complexes [Rh(l-CSe)Cl2(dppm)2] and [Rh(l-CSe)(l-DMAD)Cl2(dppm)2].