The Study of The Second-Order Asymmetric Transformation in Metal Complexes

三{N-（S-脯氨酸）二硫代氨基甲酸}钴（Ⅲ）：[Co（S-脯氨酸）_3]~（2-）的光谱<3->与三（二甲基二硫代氨基甲酸）钴（Ⅲ）的光谱相似，故前者应具有[Co（S）_6]发色团。脯氨酸的羧基不能与钴离子配位。该配合物有变旋现象，但其异构体比例可通过QAE-Sephadex阴离子交换树脂吸附而固定。此外，柱层析技术得到光学纯的非对映体。另一方面，在钡盐中的二级不对称异构化产生纯的DELTA异构体。在低温（193 K）下，K_3[Co（S-prodtc）_3]在甲醇溶液中的^1HNMR谱显示为纯的DELTA异构体。该体系将能提供有关不对称转化的新信息，去年报道了fac-[Co（R-cystineato-N，S）_3]^<3->络合物在0.1M Li_2（R-cystineate）水溶液中的变旋二级不对称转化及其动力学。现在我们也证实了异构体比例可以通过在阴离子交换树脂上吸附来冻结。游离R-或S-半胱氨酸离子的作用的检查表明，钴中心周围的反转与游离R-半胱氨酸离子的置换竞争。

The spectrum of tris{N-(S-proline)dithiocarbamato}cobaltate(III) : [Co(S-prodtc)_3]^<3-> is similar to that of tris(dimethyldithiocarbamato)cobalt(III) so that the former complex shoud have [Co(S)_6] chromophore. The proline's carboxyl groups can not coordinate to cobalt(III) Ion. This complex shows mutarotation but the isomer ratio can be fixed by adsorption on anion exchange resin of QAE-Sephadex. Furthermore, he column chromatographic technique gave optically pure diastereomers. On the other hand, the second-order asymmetric transfomation in the barium salt produced the pure DELTA isomer. At low temperature (193K) the ^1H NMR spectrum of K_3[Co(S-prodtc)_3] in methanol solution shows that of the pure DELTA isomer. This system will be able to yield new informations on asymmetric transformation.The mutarotation of the fac-[Co(R-cysteinato-N,S)_3]^<3-> complex in 0.1 M Li_2(R-cysteinate) aqueous solution has been reported last year on the second-order asymmetric transformation and its kinetics. Now we also confirm that isomer ratio can be frozen by adsorption on anion exchange resin. The examination of the effect of free R- or S-cysteinate ion indicates that the inversion around cobalt center competes with the replacement of free R-cysteinate ion.