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

Abstract A di-nuclear compound, [(CoTPA) 2 (1,4-BQ)][AsF 6 ] 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.