Cationic carboxylato complexes of dirhodium(II) with oxo thioethers: Promising catalysts with unusual coordination modes

Removal of an acetato ligand from dirhodium(II) acetato complexes with thioethers of the general structure [Rh-2(mu-OAc)(4)(RSCH(2)Z)(2)] yields the cationic complexes [Rh-2(mu-OAc)(3)(RSCH(2)Z)(2)](BF4) (R = Me, Ph; Z = C(O)OEt, CH2(O)OMe). The methylthio complex with Z = C(O)OEt has been structurally characterized and found to exhibit an unusual bidentate O-S coordination of the oxo thioether ligands. Preliminary tests indicate that the complex is a promising catalyst of the silylformylation or hydrosilylation of 1-hexyne with dimethylphenylsilane.