Asymmetric heterobimetallic mixed-valence complex trans-[(SO3)Co(cyclam)(NCS)Ru(NH3)4(NCS)](BF4): Synthesis and characterization

[(SO3)Co(cyclam)(NCS)] and [(SO3)Co(cyclam)-NCS-Ru(NH3)4(NCS)](BF4) complexes were synthesized and characterized by means of X-ray diffraction, electrochemistry, elemental analysis, and spectroscopic techniques. Crystallographic and FTIR data indicated NCS− ligand is coordinated to Co through the nitrogen atom in the monomer species. Electrochemistry and FTIR data of the material isolated after reductive electrolysis of [(SO3)Co(cyclam)(NCS)] hint that NCS− and SO32− are released thus forming [Co(cyclam)(L)2]2+, where L is solvent molecules. The formation of the heterobimetallic mixed-valence complex induced a thermodynamic stabilization of Co and Ru metal atoms in the oxidized and reduced states, respectively. According to the Robin and Day classification, a Class II system with a comproportionation constant of 5.78 × 106 is suggested for the mixed-valence complex based on the electrochemical and UV–Vis–NIR results.

Graphical abstractA mixed-valence complex containing Ru and Co was synthesized and characterized. Electrochemistry and spectroscopic data acquired for the asymmetric heterobimetallic mixed-valence complex [(SO3)Co(cyclam)-NCS-Ru(NH3)4(NCS)](BF4) indicated electronic communication between the metal centers with a comproportionation constant of 5.78 × 106 which is typical of a Class II system.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► IR and X-ray data indicated N-bonding for NCS in a cyclam-Co(III) starting complex. ► Electrochemistry and IR indicated no cyclam demetalation after reduction of Co(III). ► The formation of the binuclear complex implied stabilization of Co(III) and Ru(II). ► Mixed-valence complex showed communication between Co and Ru metal centers. ► Electrochemistry and UV–Vis–NIR data suggested a mixed-valence system of Class II.