Valence tautomerism and photodynamics observed in a dinuclear cobalt-tetraoxolene compound

Abstract

A di-nuclear compound, [(CoTPA)2(1,4-BQ)][AsF6]3 (1) (TPA=tris(2-pyridylmethyl)amine, 1,4-BQ=deprotonated 2,5-dihydroxy-1,4-benzoquinone), was formed by one electron oxidation of [(CoTPA)2(1,4-BQ)]2+ cations. The compound was characterized by X-ray diffraction, electrochemistry, ESR, thermal- and photo-induced magnetic measurements. Variable temperature magnetic measurements have demonstrated that valence tautomeric transition with a small hysteresis around room temperature and photo-excited phenomenon is exhibited. In addition, temperature-dependent hs–ls relaxation of the converted high-spin fraction after irradiation was also studied.