溶液中过渡金属水合离子内氛重组能的离子—偶极子俘获力场模型

A Model of Ion-Dipole Capture Force Field for Inner-Sphere Reorganization Energy of Transition Metal Hexa-aquocations in Solution

本文基于重组现象简单的改进模型及离子—偶极子俘获力场势函数，提出了描述电子转移过程中溶液水合离子内氛重组织效应的能量指标的一种新的形式。计算结果表明该工作有效地改进了前人的工作，取得了与实验光谱标度数据一致的规律性，并与光发射实验结果吻合较好，它避免了因缺乏溶液中可信的振动光谱数据在计算内氛重组能上的困难，通过易得的离子和配体的物理量给出了一种简便的分析方法。

Abstract From the view of structure of coordination ions, the effect of the structural reogranization energy (RE) of reactants in electron transfer processes to electron transfer rate may be divided into two parts: inner-sphere factor (contribution from the ion-ligand bond length stretching)and outter-sphere factor (contribution from the solvent). The outter-sphere RE may be accurately calculated via the Marcus theory of nonequilibrium solvent polarization, but the inner-sphere formalism are George-Griffith's model whose applicability is usually limited by the paucity of the reliable vibrational spectroscopic data and Tunuli's formalism of RE of oscillator potential by calculating the force constants of reorganized state in terms of ion-dipole interaction potential which effectively improved RE results. But, there are also some errors in them, the reason is that the change relationship between the energy of complex ions and ion-ligand bond length in solution doesn't completely satisfy harmonic oscillator model, the bigger the equilibrium displacement, the bigger the energy error. Both of cxperiment and theory indicate that the cubic term correction of harmonic oscillator potential can give a better fit to actual potential curve in a large degree. Based on a simple improved model of reorganization phenomenon and ion-dipole capture force field potential, a new formalism of energy index describing the inner-sphere reorganization effect of hydrated ions in solution involved in electron-transfer processes is presented in this paper, the calculation results indicate that this work effectively improve early ones, and give a better agreement with experimental spectroscopic scale data and photoemission cxperimentul results, and avoid the difficulty to calculate inner-sphere RE under the condition of the scarcity of vibrational spectroscopic data in solution, and present a new simple analysis method by the physical parameters of ions and ligands which is chained easily.