Conditions for chiral asymmetry generation in the preparation of the chiral octahedral cobalt complex

We have reported that the random chiral asymmetry generation, which is a sp ontaneous preferential generation of one enantiomer, was observed in the sy nthesis of a chiral octahedral cobalt complex, cis-[CoBr(NH3) (en)(2)]Br-2. In this article, we review our studies to explain in this system the autoc atalytic growth of small enantiomeric excess that arises due to statistical fluctuations. One important experimental finding was that the rate of chir al autocatalysis increased with increasing the degree of supersaturation. F urthermore, our numerical simulation indicates that even small inhomogeneit ies in the reaction system may play a significant role because their effect is amplified by the autocatalytic reaction under appropriate conditions. I n a small volume, fluctuations in concentration can grow if the autocatalyt ic growth overcomes the diffusional loss of the excess concentration from t his volume. This may makes the enantiomeric excess of the chiral complex ra ndomly fluctuate from run to run. (C) 2001 Wiley-Liss, Inc.