HCN→HNC异构化反应过渡态附近的拓扑特性

电荷密度拓扑分析方法(topological analysis of charge distribution)已经被广泛应用于研究化合物的各种静态性质及反应特性.对IRC反应途径上过渡态附近构型的拓扑性质研究报导较少.本工作是用电荷密度分布的拓扑分析方法对HCN→HNC异构化反应IRC过渡态附近的性质进行了研究.对电荷密度分布拓扑分析和IRC途径确定选用相同的基组,得到了一些新的结论。

The Topological Characteristics of the Structures in the Vicinity of Transition State of HCN→HNC Isomerization

In this paper,thermal isomerization of HCN to isocyanide HNC has been studied. The topological properties of the structures of some points on IRC path in the vicinity of transition state have been analyzed. It is found that the transition state for HCN→HNC isomerization reaction is a bond switching point on IRC path in view of its topological properties. It is a point wherc the "old" chemical bond H—C begins to break and a "new" bond between H atom and the bond critical point of CN begins to form and this state lasts for a period about ΔS=0.3 (from S=0.00 to S=0.30) on the IRC path. The changes of other properties along the IRC reaction path has also been discussed.Together with the reverse reaction, it is realized that the changing of topological properties of structures in the vicinity of transition state on IRC path is different for exothermal and endothermal reactions.