1993 年 51 巻 7 号 p. 592-607
Optically active a carbon-chiral 1-substituted ethyl and 1, 2-disubstituted ethyl bis (dimethylglyoximato) cobalt complexes were prepared by resolution of chiral axial base-coordinated complexes followed by ligand displacement of the chiral axial base with achiral base. An unprecedented type of chiral octahedral cobalt complexes, trans- [Co (AB) 2 (X) (Y)], have also been synthesized enantioselectively. By taking advantage of the features of these chiral complexes, some precise information was obtained on the mechanism of Co-C bond formation and cleavage of the alkyl cobaloxime complexes, and Co-C bond dissociation energies were estimated which, in turn, made it possible to estimate steric and electronic effects on the Co-C bond cleavage quantita-tively.
Unexpectedly, these complexes lead to the findings of X-ray-induced racemization of α carbon-chiral cobalt complexes in the crystalline-state, solid state-specific phenomena in the solid state photoracemization, unidirectional β to α (solid-state specific) photoisomerization. The mechanisms of these reactions are elucidated based on the X-ray structural analyses.