Synthetic, structural, spectroscopic, and electrochemical studies of mixed sandwich Rh(III) and Ir(III) complexes involving Cp* and tridentate macrocycles

Six heteroleptic mixed sandwich complexes containing η5-Cp*, the Group 9 transition metal ions Rh(III) or Ir(III), and three tridentate macrocycles (trithia or triazacrowns) have been successfully prepared. All complexes have the general formula [M(L)(Cp*)]2+ (M = Ir(III) or Rh(III), L = macrocycle) and exhibit a distorted octahedral structure involving three donor atoms from the macrocycle and the facially coordinating carbocyclic Cp* ligand. Our results are consistent with the role that the π acidity plays in thiacrown ligands, and the metal-thioether π interaction is enhanced in the presence of strongly donating ligands like Cp*.