Electrostatic effects in coordination kinetics. Reaction of nickel(II) ion with a cationic unidentate ligand as a function of solvent dielectric
Electrostatic effects in coordination kinetics. Reaction of nickel(II) ion with a cationic unidentate ligand as a function of solvent dielectric
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配位动力学中的静电效应。
DOI：
10.1021/ic50128a037
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发表时间：
1973
影响因子：
4.6
通讯作者：
D. Rorabacher
中科院分区：
文献类型：
--
作者：
Chin;D. Rorabacher
采用温度跳变弛豫技术研究了溶剂化Ni （II）离子与阳离子配体iV， yV， ar -三甲基乙二铵离子（tmen+）在含0-90%甲醇（重量）的甲醇-水混合物中，在25µ= 0.3 M条件下，溶剂化Ni （II）离子与溶剂介电的关系。将实验生成速率常数与Ni （II）与中性氨配体反应的相应值进行比较，发现导致络合物形成的“有效”离子对中Ni （II）与tmen*之间的电荷中心距离为6.5 A。结合先前生成的反应位点中心到中心距离为4a的值以及估计的空间因子，该值允许计算带电双齿配体与金属离子相互作用的“反应性”离子对形成常数。当前处理中计算的有效性受到本研究所需的相对较高的离子强度的限制。考虑了涉及氨基酸和单质子化二胺的配位反应的机制含义。
The kinetics of solvated Ni (II) ion reacting with a cationic ligand, iV, yV, Ar-trimethylethylenediammonium ion (tmen+), have been studied as a function of solvent dielectric in methanol-water mixtures containing 0-90% methanol (by weight) at 25, µ= 0.3 M using the temperature-jump relaxation technique. By comparison of the experimental formation rate constants to the corresponding values for Ni (II) reacting with the neutral ammonia ligand, the value of the chargecenter-to-center distance between Ni (II) and tmen* in the “effective” ion pairs leading to complex formation is found to be 6.5 A. In con-junction with a previously generated value for the reactive sitecenter-to-center distanceof 4 A along with estimated steric factors, this value permits the calculation of a “reactive” ion-pair formation constant for charged bidentate ligands interacting with metal ions. The validity of the calculations in the current treatment is limited by the relatively high ionic strength necessitated in this study. The mechanistic implications for coordination reactions involving amino acids and monoprotonated diamines are considered.