摘要
应用Ｍａｒｃｕｓ双球模型计算溶剂重组能λｓ时，在ＡＭ１法优化给受体几何构型基础上，提出了共轭体系电子云分布的扁球模型，并用统计的方法求出了ｒＤ／Ａ，同时依照Ｍｉｌｌｅｒ等的处理办法，结合其他理论及实验证据将电子转移交叉反应中联苯分子的扭转能计入溶剂重组能λｓ中，从而用实验速率常数拟合出含扭转能的λｓ值．此实验拟合值与扁球法得到的λｓ计算值吻合得很好．通过比较理论值与实验值，发现了给受体间距的大小、受体分子的变化、溶剂的不同对λｓ计算值相对λｓ实验值的偏差的影响，直接证实了电子给受体的耦合作用，溶剂分子参与的超交换电子转移及溶质溶剂分子表面相互作用等量子因素造成的实际反应体系对溶剂经典连续介质模型的偏离．
In the calculation of solvent reorganization energy by Marcus's two-sphere model, we presented a flat sphere model based on benzene-solvent system's exact geometry structure to describe the electron cloud of conjugated systems. We figured out the radii of electron donors and acceptors by using statistics method, after AM(1), geometry optimization, and then calculated lambda (s). Besides, according to Miller's experiment and consulting McHale and other researchers' Raman Spectrometry results, we supposed that the solute molecular low frequency torsion gave no contribution to lambda (s). when the frequency was too small and the lambda obtained from flat sphere model had contained low frequency contribution. This revised lambda (s), was in agreement with the value figured out by subtracting revised lambda (s) from experimental lambda value. By comparing them, we found that the distance between donor and acceptor, the alteration of acceptor and solvent affected the deviation of calculated lambda (s) from experiment values. Finally, we confirmed that the D-A coupling, super exchange mediated by solvent molecule, surface interaction of solvent-solute molecules and other similar quantum effects would reduce the classical value of A(s), thus contribute to ET reaction. Our results proved the deviation of practical reaction systems to the continuum dielectric theory and reflected the necessity of describing the behaviors of solvent and solute molecules using molecular model.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2001年第10期924-930,共7页
Acta Physico-Chimica Sinica
基金
秦惠莙与李政道中国大学生见习进修基金资助项目
