Solid-state specific and unidirectional photoisomerization of 3-substituted propyl to 1-substituted propyl cobaloxime complexes via 2-substituted propyl complexes

Solid state-specific (gamma-->beta-->alpha )photoisomerization of 3-cyanopr opyl and 3-(methoxycarbonyl)propyl cobaloxime complexes were found to occur on visible-light irradiation. There exist considerable differences in the reaction rates, which have no relation to the basicity of the axial ligand. In the former series of complexes, the rate constant (k(2)) for the second step (beta-->alpha) is much faster than that (k(1)) for the first step. Ho wever, in the latter series of complexes, the rate constant (k(2)) for the second step tends to decrease extremely, and thus, k(2) become smaller than k(1).