Mechanistic Information from Pressure Acceleration of Hydride Formation via Proton Binding to a Cobalt(I) Macrocycle
作者:Etsuko Fujita、James F. Wishart、Rudi van Eldik
DOI:10.1021/ic011109q
日期:2002.3.1
occurring via proton transfer. Whereas the corresponding volumes of activation (DeltaV) are rather small and negative for all acids (proton donors) with pK(a) values below 8.5, significantly larger negative activation volumes are found for weaker acids (pK(a) > 9.5) containing OH groups as proton donors. In the latter case, the observed DeltaV for these protonation reactions show a correlation with the reaction
压力对质子与钴(I)大环的外消旋异构体CoL(+)结合的影响(L = 5,7,7,12,14,14-六甲基-1,4,8,11-四氮杂环十四烷- 4,11-diene),已使用脉冲辐射分解技术研究了一系列质子供体。CoL(+)与质子供体反应的二级速率常数随供体酸pK(a)的增加而降低,这与通过质子转移发生的反应一致。对于pK(a)值低于8.5的所有酸(质子供体),相应的激活量(DeltaV)相当小且为负,而对于含OH的弱酸(pK(a)> 9.5),则发现其负激活量明显更大。团体作为质子供体。在后一种情况下,