Controlled Light and Temperature Induced Valence Tautomerism in a Cobalt-o-Dioxolene Complex

The mononuclear cobalt complex of 3,5-di-tert-butylcathecolate and cyan-pyridine (Co(diox)2(4-CN-py)2) is a very versatile compound that displays valence tautomerism (VT) in the solid state, which induced by temperature, light, hard X-rays, modulated solvent crystal lattice. In our work, we used single X-ray diffraction as probe for light-induced VT state demonstrate controlled use X-rays via attenuation to avoid X-ray-induced interconversion. We report photoinduced benzene solvated crystals Co(diox)2(4-CN-py)2 illuminated with blue 450 nm light at 30 K high yield (80%) metastable hs-CoII states, also show evidence de-excitation these states using red 660 light. Such high-yield had never been experimentally observed molecular tautomers, proving illumination triggering chain events leads ls-CoIII