Oxidative addition of methyl iodide and CO migratory insertion in a cationic rhodium complex of a S,N,S tridentate ligand

The cationic rhodium(I) carbonyl complex mer-[Rh(L)(CO)]PF6 coordinated by a tridentate S,N,S donor ligand (L = 2,6-bis(benzylthiomethyl)pyridine) reacts with MeI to give the corresponding acetyl derivative [Rh(L)(COMe)I]PF6, by consecutive oxidative addition-migratory insertion reactions via observable methyl-rhodium(III) intermediate complexes. Rate constants and activation parameters have been obtained for both reaction steps in MeCN, and compared with those of complexes coordinated by mono- and bidentate ligands. This is the first report on the organometallic reactivity of a rhodium(I) and carbonyl complex of S,N,S ligands.