The racemic complex of (1-cyanoethyl)(piperidine)cobalozime crystallizes in an isomorphous structure to its chiral one. In either crystal one of the two crystallographically independent molecules is gradually inverted to have the opposite configuration on exposure to visible light retaining the single crystal form. This brings about optical enrichment for the crystal of racemic complex. The final structures produced by the complete irradiation for the chiral and racemic crystals are converged to the same one. The ratio of the R and S configuration of the partly inverted molecule in the final structure is not 50:50 but 60:40, which is well explained by the shape of the reaction cavities for the cyanoethyl group before and after the partial inversion. Another racemic complex crystal with pyrrolidine instead of piperidine seems to exhibit a similar optical enrichment.