The formation kinetics of the complex, [Ru(CN)5INH]3−, formed through the ligand substitution reaction between isoniazid (INH) and aquapentacyanoruthenate(II) ([Ru(CN)5H2O]3−), have been investigated, under pseudo first-order conditions, as a function of concentrations of [INH] and [Ru(CN)5H2O]3−, ionic strength and temperature at pH = 4.0 ± 0.02 in 0.2 M NaClO4 spectrophotometrically at 502 nm (λmax of intense yellow colour product [Ru(CN)5INH]3−) corresponding to metal-to-ligand charge-transfer transitions, in aqueous medium. The pseudo first-order condition was maintained by taking at least 10% excess of [INH] over [Ru(CN)5H2O]3−. The stoichiometry of the reaction product was found to be 1:1 which was further supported and characterized using elemental analysis, infrared, nuclear magnetic resonance and mass spectrometric techniques. Thermodynamic and kinetic parameters have also been computed, using the Eyring equation, and the values of ΔH≠, Ea, ΔG≠ and ΔS≠ were found to be 47.3 kJ mol−1, 49.8 kJ mol−1, −8.62 kJ mol−1 and 187.6 J K−1mol−1, respectively. The reaction was found to obey first-order kinetics with respect to [INH]. It exhibited a negative salt effect on the rate upon variation of ionic strength of the medium. A tentative mechanistic scheme was proposed on the basis of experimental findings.

中文翻译：

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[Ru(CN)5INH]3− 通过五氰基钌 (II) 阴离子与异烟肼之间的配体取代反应形成的动力学和机制

通过异烟肼 (INH) 和五氰基钌 (II) ([Ru(CN)5H2O]3-) 之间的配体取代反应形成的复合物 [Ru(CN)5INH]3- 的形成动力学已被研究，在伪一级条件，作为 [INH] 和 [Ru(CN)5H2O]3− 浓度、离子强度和温度的函数，pH = 4.0 ± 0.02 在 0.2 M NaClO4 中，在 502 nm 处分光光度计（强黄色的λmax）产物 [Ru(CN)5INH]3-) 对应于金属到配体的电荷转移跃迁，在水性介质中。通过使 [INH] 超过 [Ru(CN)5H2O]3- 至少 10% 来维持伪一级条件。发现反应产物的化学计量比为 1:1，使用元素分析、红外、核磁共振和质谱技术进一步支持和表征。还使用 Eyring 方程计算了热力学和动力学参数，发现 ΔH≠、Ea、ΔG≠ 和 ΔS≠ 的值为 47.3 kJ mol-1、49.8 kJ mol-1、-8.62 kJ mol-1和 187.6 JK−1mol−1，分别为。发现该反应服从关于 [INH] 的一级动力学。它在介质离子强度变化时对速率显示出负盐效应。在实验结果的基础上提出了一个暂定的机械方案。它在介质离子强度变化时对速率显示出负盐效应。在实验结果的基础上提出了一个暂定的机械方案。它在介质离子强度变化时对速率显示出负盐效应。在实验结果的基础上提出了一个暂定的机械方案。