Hydrophobic Vitamin B12. II. Coordination Geometry and Redox Behavior of Heptamethyl Cobyrinate in Nonaqueous Media
Hydrophobic Vitamin B12. II. Coordination Geometry and Redox Behavior of Heptamethyl Cobyrinate in Nonaqueous Media
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疏水性维生素 B12。
DOI：
10.1246/bcsj.57.405
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发表时间：
1984
影响因子：
4
通讯作者：
T. Ohno
中科院分区：
文献类型：
--
作者：
Y. Murakami;Y. Hisaeda;A. Kajihara;T. Ohno
在极性溶剂（甲醇）中，钴（Ⅱ）七甲基碘化钴（Ⅱ）酯·I的核钴（Ⅱ）离子以碘离子为配位原子，呈Co-N_4型畸变四方平面构型;在非极性溶剂（二氯甲烷、苯和甲苯）中，核钴（Ⅱ）离子以碘离子为配位原子，呈Co-N_4 I型畸变四方锥构型。用循环伏安法和控制电位电解法研究了钴（II）酯·I和钴酸七甲酯高氯酸盐[Cob（II）酯] ClO 4在不同有机溶剂中的氧化还原化学。Co（II）/Co（I）和Co（III）/Co（II）的氧化还原电位[钴（II）酯]二氧化氯表现出阴极位移作为溶剂的碱性或极性的提高，并被发现是在阳极侧相对于相应的电位CoII（TPP）在相同的条件下。结合微环境对维生素B12氧化还原行为的影响，讨论了介质对疏水性维生素B12氧化还原行为的影响。
The nuclear cobalt(II) ion in heptamethyl cobyrinate iodide, Cob(II)ester·I, was found to assume a distorted square-planar geometry of Co–N4 type with iodide as a counterion in a polar solvent (methanol) and a square-pyramidal one of Co–N4I type with the iodide ion coordinated at one of the axial positions in apolar solvents such as dichloromethane, benzene, and toluene. The redox chemistry of Cob(II)ester·I and heptamethyl cobyrinate perchlorate, [Cob(II)ester]ClO4, was investigated in various organic solvents by means of cyclic voltammetry and controlled-potential electrolysis. The Co(II)/Co(I) and Co(III)/Co(II) redox potentials for [Cob(II)ester]ClO4 exhibited cathodic shifts as either solvent basicity or polarity was raised, and were found to be in the anodic side relative to the corresponding potentials for CoII(tpp) under identical conditions. The medium effect on the redox behavior of hydrophobic vitamin B12 was discussed in connection with the microenvironmental effect on vitamin B12 placed in th...