A comparison of the rates of electron exchange reactions of ammine complexes of ruthenium(II) and -(III) with the predictions of adiabatic, outer-sphere electron transfer models
A comparison of the rates of electron exchange reactions of ammine complexes of ruthenium(II) and -(III) with the predictions of adiabatic, outer-sphere electron transfer models
复制标题
钌(II)和-(III)氨络合物的电子交换反应速率与绝热外层电子转移模型的预测的比较
DOI：
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发表时间：
1979
期刊：
影响因子：
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通讯作者：
N. Sutin
中科院分区：
文献类型：
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作者：
G. Brown;N. Sutin
Ru(NH/sub 3/)/sub 6//sup 3+/2+/、Ru(NH/sub 3/)/sub 4/(bpy)/sup 3+2+/和Ru(NH/sub 3/)/sub 2/(bpy)/sub 2//sup 3+/2+/电子交换反应的速率常数已通过涉及配体细微修饰的技术测量。对于 Ru(NH/sub 3/)/sub 6//sup 3+/2+/ 交换，25/sup 0/C 下的速率常数（M/sup -1/s/sup -1/，中）为 3.2 x 10/sup 3/、0.1 M CF/sub 3/SO/sub 3/H； 7.7 x 10/sup 5/、0.1 M CF/sub 3/SO/sub 3/H 和 2.2 x 10/sup 6/、0.1 M HClO/sub 4/，用于 Ru(NH/sub 3/)/sub 4/(bpy)/sup 3+/2+/ 交换； 8.4 x 10/sup 7/、0.1 M HClO/sub 4/，用于 Ru(NH/sub 3/)/sub 2/(bpy)/sup 3+/2+/ 交换。 Ru(NH/sub 3/)/sub 4/(bpy)/sup 3+/2+/交换反应的速率常数和活化参数确定为离子强度的函数（k = 4.1 x 10/sup 4/ M/sup -1/s/sup -1/，..delta..H 不等于 4.0 kcal mol/sup -1/，并且 ..delta..S 不等于至 -24 cal deg/sup -1/ mol/sup -1/（零离子强度和 25/sup 0/C）。本工作中确定的速率常数与类似的 Ru(NH/sub 3/)/sub 5/py/sup 3+/2+/ 和 Ru(bpy)/sub 3//sup 3+/2+/ 交换反应的速率常数与理论模型的预测进行了比较。 logmore » k/sub ex/ 与 1/anti r 的图具有良好的线性关系，其中 anti r 是活化络合物中钌中心的平均间距。与传统离子对预平衡模型相比，基于反应碰撞公式推导的 Marcus 模型与零离子强度下观察到的速率常数和活化参数具有更好的一致性。与预测相反，交换率随着离子强度的增加而增加主要反映在活化焓的降低上。 6 个数字，5 个表格。« 更少
The rate constants for the Ru(NH/sub 3/)/sub 6//sup 3+/2+/, Ru(NH/sub 3/)/sub 4/(bpy)/sup 3+2+/, and Ru(NH/sub 3/)/sub 2/(bpy)/sub 2//sup 3+/2+/ electron exchange reactions have been measured by a technique involving subtle modifications of the ligands. The rate constants (M/sup -1/s/sup -1/, medium) at 25/sup 0/C are 3.2 x 10/sup 3/, 0.1 M CF/sub 3/SO/sub 3/H, for the Ru(NH/sub 3/)/sub 6//sup 3+/2+/ exchange; 7.7 x 10/sup 5/, 0.1 M CF/sub 3/SO/sub 3/H, and 2.2 x 10/sup 6/, 0.1 M HClO/sub 4/, for the Ru(NH/sub 3/)/sub 4/(bpy)/sup 3+/2+/ exchange; 8.4 x 10/sup 7/, 0.1 M HClO/sub 4/, for the Ru(NH/sub 3/)/sub 2/(bpy)/sup 3+/2+/ exchange. The rate constants and activation parameters for the Ru(NH/sub 3/)/sub 4/(bpy)/sup 3+/2+/ exchange reaction were determined as a function of ionic strength (k = 4.1 x 10/sup 4/ M/sup -1/s/sup -1/, ..delta..H is not equal to 4.0 kcal mol/sup -1/, and ..delta..S is not equal to -24 cal deg/sup -1/ mol/sup -1/ at zero ionic strength and 25/sup 0/C). The rate constants determined in this work together with those for the analogous Ru(NH/sub 3/)/sub 5/py/sup 3+/2+/ and Ru(bpy)/sub 3//sup 3+/2+/ exchange reactions are compared with the predictions of theoretical models. Good linearity was found for a plot of logmore » k/sub ex/ vs. 1/anti r, where anti r is the mean separation of the ruthenium centers in the activated complex. The Marcus model derived on the basis of a reactive collision formulation gives better agreement with the observed rate constants and activation parameters at zero ionic strength than the conventional ion-pair preequilibrium model. Contrary to prediction, the increase in exchange rate with increasing ionic strength is reflected primarily in a decreased enthalpy of activation. 6 figures, 5 tables.« less