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 [Rh2(m-OAc)4(RSCH2Z)2] yields the cationic complexes [Rh2(m-OAc)3-(RSCH2Z)2](BF4) (R ) Me, Ph; Z ) C(O)OEt, CH2C(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.