气相离子-分子反应B2H3-+CS2——B2H3S-+CS的理论研究

用密度泛函方法B3LYP/6-311++G(d,p)和高级电子相关的偶合簇法CCSD(T)/6-311++G(d,p)研究了气相离子-分子反应B₂H₃^-+CS₂B₂H₃S^-+CS的机理.结果表明,B₂H₃最可能进攻CS₂中碳原子形成三元环中间体,随后通过氢迁移和最终消除CS的反应步骤形成硫原子转移产物H₃BBS^-+CS,反应大量放热且不需要活化能.B₂H₃直接对CS₂中硫原子进攻夺取硫原子的反应方式存在一定能垒阻碍.计算结果有助于深入了解B₂H₃,B₃H-6和B₄H₇^-等缺电子硼氢负离子的反应行为.

Theoretical Study on the Gas Phase Reaction:B2H-3+CS2B2H3S-+CS

The mechanism for the gas phase ion molecule reaction B 2H - 3+CS 2B 2H 3S -+CS has been investigated theoretically by using the B3LYP/6 311++G( d,p ) and the high level electron correlation CCSD(T)/6 311++G( d,p ) single point levels. It is shown that the B 2H - 3 anion may attack the carbon atom of CS 2 to form a three membered ring intermediate followed by a H shift and subsequently a CS extrusion steps to reach the final dissociation product H 3BBS -+CS. The reaction is largely exothermic and no activation energy is needed for this three membered ring mechanism. On the other hand, an activation barrier is found for the sulfur atom abstraction reaction initiated by the sulfur attack of B 2H - 3 towards CS 2. The calculated results presented in this paper may be helpful for understanding the chemical behavior of electron deficient boron hydride anions such as B 2H - 3, B 3H - 6 and B 4H - 7, etc..