Novel redox active rhodium(iii) complex with bis(arylimino)acenaphthene ligand: synthesis, structure and electrochemical studies

(Rhodium trichloride reacts with 1,2-bis[(2,6-diisopropylphenyl)imino] acenaphthene (dpp-bian) to afford new octahedral complex mer-[Rh(dpp-bian)(H2O)Cl3]·CH2Cl2. The CV of mer-[Rh(dpp-bian)(H2O)Cl3] in MeCN shows an irreversible reduction that corresponds to the RhIII/RhI couple, followed by reversible or quasi-reversible cathodic waves assigned to reduction of the dpp-bian ligand. DFT calculations confirm the assignment of the redox processes and predict the elimination of two chloride ligands from axial positions upon two-electron reduction of mer-[Rh(dpp-bian)(H2O)Cl3] with the formation of a RhI square-planar complex [RhI(dpp-bian)(H2O)Cl].