BrSSCl和SSBrCl相对稳定性的理论研究

A DFT Investigation on the Relative Stabilities of BrSSCl and SSBrCl Isomers

采用量子化学中的密度泛函理论,在B3LYP/6-311+G(3df)水平上全优化得到了S_2BrCl分子线型和分叉型2种异构体的平衡结构,同时对可能发生的分子内原子迁移过程的过渡态进行了考察。计算结果表明,从能量角度看,线型的BrSSCl为稳定构型。采用统计热力学及过渡态理论,研究了2种平衡结构之间相互转化的热力学和动力学性质。根据计算结果,无论是Cl迁移还是Br迁移,分子内的原子迁移都需要较高的活化能,并且迁移速度较慢。

B3LYP calculations of density functional theory with the 6-311 + G(3df, 2p) basis set level are used to investigate the equilibrium structures and intramolecular rearrangement reactions of the linear BrSSCl and branched SSBrCl isomers. The calculated results show that the linear structure is more stable than the branched structure (lower 53. 4kJ . mol(-1) corrected with zero point vibrational energy) energetically. The calculated energy barriers for the intramolecular bromine atom transfer and chlorine atom transfer isomerization processes are 102. 9kJ . mol(-1) and 115. 3kJ . mol(-1), respectively. The kinetic results demonstrate that the isomerization is a unimolecular process, and the reaction rate is slow. This agrees with thermodynomical results. So the isomerization process should proceed via other likely processes.