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

• Published in: Chinese science bulletin 2014, Vol.59 (3), p.286-296
• Main Authors: Lü, Lingling, Wang, Xiaofang, Zhu, Yuancheng, Liu, Xinwen, Yuan, Kun, Wang, Yongcheng
• Format: Article
• Language: English
• Subjects: Activation; B3LYP; Bonding; chemical reactions; Chemistry/Food Science; Earth Sciences; Efficiency; energy; Engineering; equations; Humanities and Social Sciences; Isocyanates; Life Sciences; multidisciplinary; organic compounds; Pathways; Physics; Potential energy; Science; Science (multidisciplinary); Spin-orbit interactions; Splitting; 三重态; 交叉点; 反应机理; 异氰酸酯; 自旋; 轨道耦合; 零场分裂
• ISSN: 1001-6538; 1861-9541
• DOI: 10.1007/s11434-013-0024-5

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）.