Synthesis of a rhodium(III) triphenylphosphine complex via C S bond cleavage of an azo-thioether ligand: X-ray structure, electrochemistry and catalysis towards transfer hydrogenation of ketones

A new rhodium(III) triphenylphosphine complex having the general formula [Rh(PPh3)2(L)Cl] (1) was synthesized by C S bond cleavage of an ONS donor azo-thioether ligand (L-CH2Ph). The complex was thoroughly characterized by various spectroscopic techniques. Its single crystal X-ray structure exhibits an octahedral geometry around the rhodium(III) center. A cyclic voltammogram of the complex exhibits ligand based quasi-irreversible oxidative and reductive responses. The electronic structure, redox properties and electronic excitations in the complex were interpreted by DFT and TDDFT calculations. The complex effectively catalyzed the transfer hydrogenation reaction of ketones with high yields in i-PrOH in the presence of a base.