A Quantum Chemistry Study on the Isomerization Reaction Mechanism of ATM

The mechanism of 2-amino-5-mercapto-1,3,4-thiadiazole(AMT) isomerization reactions have been studied by B3LYP/6-31+G** and the geometric parameters of reactants, products and transition states have been located at the same calculation level. The stationary points have been conformed by vibration analysis and zero-point energy corrections have been considered. The energy of the Qcisd(T) has been counted single point by single point and the way of IRC of the reactionary course has also been counted so that the possible channel of isomerization is determined. The obtained results show that there are sixtransition states occurring in the course of isomerization reactions for different isomers, among which the isomerization from A to C is the easiest one and C is the most stable one.