A Density Functional Theory Study of the Isomerization Reaction HNC→HCN

The reaction mechanism of the isomerization:HNC→HCN has been studied by means of density functional theory (DFT) at the level of B3LYP/6-31G*.There may exist two types: one is that the HNC molecule itself proceeds via a three-centred transition states to transform by its interior hydrogen-bonded; the other is that two HNC molecules associate at first and then proceed via a six-centred transition states to transform by its exterior hydrogen-bonded.The results show that: the mechanism of the six-centred construction makes the activation energy of the isomerizing reaction reduce dramatically.