Theoretical study of spin-orbit coupling and zero-field splitting in the spin-forbidden two-state reaction between cobaltacyclopentadiene and isocyanate  

作　　者：Lingling L Xiaofang Wang Yuancheng Zhu Xinwen Liu Kun Yuan Yongcheng Wang 

机构地区：[1]College of Life Science and Chemistry,Tianshui Normal University [2]College of Chemistry and Chemical Engineering,Northwest Normal University

出　　处：《Chinese Science Bulletin》2014年第3期286-296,共11页

基　　金：supported by the National Natural Science Foundation of China(21263022);University Research Fund of Gansu Province Financial Department,and"QingLan"Talent Engineering Funds of Tianshui Normal University

摘　　要：The two-state reaction mechanism of CpCo(C_4H_4)with isocyanate on the triplet and singlet potential energy surfaces has been investigated at the B3LYP level.A study is described for the computation of spin-orbit coupling of triplet state of the minimal energy crossing point(CP)with their singlet states and of the zerofield splitting(ZFS)parameters of the triplet states,including the full one-and two-electron terms of the BreitPauli Hamiltonian.There are two key crossing points along this two-state reaction pathway.The first crossing point—CP2 exists near^1B.The reacting system will change its spin multiplicity from the triplet state to the singlet state near this crossing region.Although the spin-orbit coupling interaction and ZFS D-tensor of the CP2 region are very strong,the reaction system will occur the reverse intersystem crossing from T_1 to S_0.Therefore,its spin-flip efficiency may be lower.The second crossing point,CP3will again change its spin multiplicity from the singlet state to the triplet state in the Co-Cr bond activation pathway,leading to a decrease in the barrier height of^1TS(CF)from19.5 to 9.5 kcal/mol(1cal=4.182 J),and the efficiency of intersystem crossing from S_0 to T_1 is high because the larger spin-orbit coupling(SOC)matrix elements will result in the overpopulations of the three sublevels of T_1(3.30×10^(-1),3.32×10^(-1),and 3.38×10^(-1),respectively).The two-state reaction mechanism of CpCo（C4H4） with isocyanate on the triplet and singlet potential energy surfaces has been investigated at the B3LYP level. A study is described lbr the computation of spin-orbit coupling of triplet state of the minimal energy crossing point （CP） with their singlet states and of the zero- field splitting （ZFS） parameters of the triplet states, including the full one- and two-electron terms of the Breit- Pauli Hamiltonian. There are two key crossing points along this two-state reaction pathway. The first crossing point-- CP2 exists near 1B. The reacting system will change its spin multiplicity from the triplet state to the singlet state near this crossing region. Although the spin-orbit coupling interaction and ZFS D-tensor of the CP2 region are very strong, the reaction system will occur the reverse intersystem crossing from T1 to S0. Therefore, its spin-flip efficiency may be lower. The second crossing point, CP3 will again change its spin multiplicity from the singlet state to the triplet state in the Co--C,/bond activation pathway, leading to a decrease in the barrier height of ITS（CF） from 19.5 to 9.5 kcal/mol （1 cal =4.182 J）, and the efficiency of intersystem crossing from So to T1 is high because the larger spin-orbit coupling （SOC） matrix elements will result in the overpopulations of the three sublevels of Ti （3.30 × 10-1, 3.32 × 10 -1, and 3.38× 10-l, respectively）.

关 键 词：轨道耦合 异氰酸酯 零场分裂 反应机理 自旋 B3LYP 三重态 交叉点 

分 类 号：O621.2[理学—有机化学]