电子转移反应O_2+O_2^(·-)→O_2^(·-)+O_2的从头算研究  

Ab intio Studies on the Electron Transfer O_2 + O_2^(·-)→O_2^- + O_2

作　　者：王彦妮[1] 张小东[1] 刘扬[1] 张启元[1] 

机构地区：[1]中国科学院化学研究所

出　　处：《化学学报》2000年第1期19-23,共5页Acta Chimica Sinica

基　　金：国家重点基础研究及发展规划项目基金;国家自然科学基金(29733100;39870208;39890390)资助项目

摘　　要：利用ab initio方法,在UHF,UMP2及不同基组3-21G,6-31G~*,6-311+G~*和UMP2(full)/6-311+G~*水平上,研究了O_2/O_2^-自交换电子转移反应.优化了电子转移前后反应物和产物的结构,研究了体系能量的变化,计算了自交换电子转移反应的内重组能.对UHF方法和UMP2方法的计算结果进行了比较,并与实验结果进行了对照.结果表明UHF方法由于没有考虑组态相互作用,计算结果存在较大偏差,UMP2(full)/6-311+G~*水平上的计算结果与实验值吻合较好.在UMP2(full)/6-311+G~*水平上计算了气相自交换电子转移反应速率常数.在优化了电子转移复合物结构的基础上考虑了溶剂效应的影响,计算了水溶液中的溶剂重组能.研究结果表明O_2/O_2^-体系电子转移反应的活化能主要来源于溶剂重组能的贡献.最后计算了该反应在水溶液中的反应速率常数.理论计算结果与实验值吻合得很好.Ab initio studies in the changes in structures and energy the of the O2/O2- system in the electron transfer process were performed by using UHF and UMP2 methods with basis sets of 3-21G, 6-31G* , 6 -311 + G* , UMP2(full)/6 - 311 + G* respectively. It is shown that the UMP2 method is necessary in the calculation for this system, because the electron correlation is important. The bond lengths of O2 and O2-calculated with UMP2 ( full) /6 - 311 + G * are in agreement with the experimental results. The calculated internal reorganization energy of the electron transfer reaction, the activation energy, and the rate constant are77.14kJ/mol, 19.29kJ/mol and ca. 3.17 × 107dm3·mol-1·s-1 respectively, for the self - exchange reaction of O2/O2- in the gas phase. Structures of the electron transfer activated complex of O2/O2- system in aqueous solution were optimized. The calculated solvent reorganization energy is 146.09kJ/mol. The results show that the activation energy is 55.81kJ/mol, and the rate constant of O2/O2- self- exchange reaction inaqueous is about 1.00×102dm3·mol-1·s-1,which is in agreement with the experimental result.

关 键 词：电子转移 从头算 氧分子 超氧阴离子 自由基 

分 类 号：O643.1[理学—物理化学]