LIGAND-SUBSTITUTION REACTIONS OF AQUACOBALAMIN (VITAMIN-B(12A)) REVISITED - CONCLUSIVE EVIDENCE FOR THE OPERATION OF A DISSOCIATIVE INTERCHANGE MECHANISM

被引：39

作者：

MEIER, M ^{[1
]}

VANELDIK, R ^{[1
]}

机构：

[1] UNIV WITTEN HERDECKE,INST INORGAN CHEM,STOCKUMER STR 10,W-5810 WITTEN,GERMANY

来源：

INORGANIC CHEMISTRY | 1993年 / 32卷 / 12期

关键词：

D O I：

10.1021/ic00064a011

中图分类号：

O61 [无机化学];

学科分类号：

070301 ; 081704 ;

摘要：

A detailed kinetic study of the substitution of aquacobalamin by thiourea and substituted thiourea was performed as a function of entering ligand concentration, temperature, and pressure. The observed rate and activation parameters for the forward and reverse reaction steps conclusively confirm the operation of a dissociative interchange mechanism. For instance, the volumes of activation for both the forward and reverse reactions have values between + 6 and + 10 cm3 mol-1, accompanied by positive values for the entropy of activation. The conclusions reached in an earlier study dealing with the substitution by pyridine are in error and are reinterpreted in the light of the new data. The results are compared to all available literature information, which confirms the mechanistic assignment made in this study.

引用

页码：2635 / 2639

页数：5

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