ESR Study of Light-Induced Valence Tautomerism of a Dinuclear Co Complex

Light-induced valence tautomerism (LIVT) of a dinuclear complex, [{Co(dpqa)}(2)(dhbq)](PF(6))(3) (1), was investigated by ESR analysis of dhbq(3-). LIVT phenomena were observed in the sample diluted in the glass matrix as well as that in powder form. The signal decay and the relaxation were analyzed by double exponential fitting; the results suggest a two-step mechanism. Quantum mechanical tunneling was clearly observed in the glass matrix.