Development of a versatile synthesis method for trinuclear Co(iii), Rh(iii), and Ir(iii) dithiolene complexes, and their crystal structures and multi-step redox properties.

Triangular trinuclear Co(iii), Rh(iii), and Ir(iii) dithiolene complexes, [[M(3)(eta(5)-C(5)Me(5))(3)(S(6)C(6))] (M = Co, Rh, Ir), which have not been obtained by the trimerization of mononuclear complexes, were synthesized via a new synthetic route, that is, the reaction of benzenehexathiol and [(eta(5)-C(5)Me(5))Co(CO)I(2)], [Rh(eta(5)-C(5)Me(5))Cl(2)](2) and [Ir(eta(5)-C(5)Me(5))Cl(2)](2), respectively, under basic conditions. Single crystal X-ray diffraction measurements were carried out and their crystal structures were determined. Electrochemical measurements revealed that the trinuclear complexes exhibit three-step one-electron redox reactions and form mixed valence complexes. Studies on the stabilities of their mixed valence states and the X-ray crystal structure analyses revealed that the through-bond internuclear electronic interaction and the aromaticity of central benzene ring decrease in the order of Co > Rh > Ir.