TY - JOUR
T1 - Generation of an optically active octahedral cobalt complex by a chiral autocatalysis
AU - Asakura, Kouichi
AU - Kobayashi, Kayo
AU - Mizusawa, Yoshinori
AU - Ozawa, Takehiro
AU - Osanai, Shuichi
AU - Yoshikawa, Sadao
PY - 1995/6/15
Y1 - 1995/6/15
N2 - Optically active cis-[CoBr(NH3)(en)2]Br2 could be readily obtained by the reaction of optically inactive [Co(H2O)2{(OH)2Co(en)2}2](SO4)2 with ammonium bromide in a water suspension. The optically active cis-[CoBr(NH3)(en)2]Br2 was not readily racemized in its aqueous solution, indicating it not to be produced by total spontaneous resolution but by asymmetric synthesis. This synthesis was exclusively observed when the weight ratio of[Co(H2O)2{(OH)2Co(en)2}2](SO4)2 to water was above 0.31. Since the crystal of each enantiometer of cis-[CoBr(NH3)(en)2]Br2 introduced into the reaction system lead to the preferential production of the same enantiomer, chiral autocatalysis was shown to be performed during the reaction. In the concentrated suspension, crystallization of cis-[CoBr(NH3)(en)2]Br2 that was produced by the reaction would be started during the relatively early stage of the reaction. If several crystals to be initially produced are enantiomerically unequivalent by statistical fluctuation, it may cause the spontaneous generation of the enantiomeric predominance.
AB - Optically active cis-[CoBr(NH3)(en)2]Br2 could be readily obtained by the reaction of optically inactive [Co(H2O)2{(OH)2Co(en)2}2](SO4)2 with ammonium bromide in a water suspension. The optically active cis-[CoBr(NH3)(en)2]Br2 was not readily racemized in its aqueous solution, indicating it not to be produced by total spontaneous resolution but by asymmetric synthesis. This synthesis was exclusively observed when the weight ratio of[Co(H2O)2{(OH)2Co(en)2}2](SO4)2 to water was above 0.31. Since the crystal of each enantiometer of cis-[CoBr(NH3)(en)2]Br2 introduced into the reaction system lead to the preferential production of the same enantiomer, chiral autocatalysis was shown to be performed during the reaction. In the concentrated suspension, crystallization of cis-[CoBr(NH3)(en)2]Br2 that was produced by the reaction would be started during the relatively early stage of the reaction. If several crystals to be initially produced are enantiomerically unequivalent by statistical fluctuation, it may cause the spontaneous generation of the enantiomeric predominance.
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U2 - 10.1016/0167-2789(95)00013-T
DO - 10.1016/0167-2789(95)00013-T
M3 - Article
AN - SCOPUS:0002788369
SN - 0167-2789
VL - 84
SP - 72
EP - 78
JO - Physica D: Nonlinear Phenomena
JF - Physica D: Nonlinear Phenomena
IS - 1-2
ER -