Density functional study of the reaction paths of formamidine

Abstract

Density functional theory (DFT) is used to study the reaction paths of formamidine. The E conformer of formamidine is predicted to be more stable (1.4 kcal mol^-1) than the Z. The energy of activation is estimated to be 26.7 kcal mol^-1 for the E <img src='http://www.niscair.res.in/jinfo/rightarrow.gif' border=0> Z isomerization. The E isomer can undergo 1,3-sigmatropic shift and the energy barrier is estimated to be 47.6 kcal mol ^-1 Unimolecular decomposition of the Z isomer to HCN and NH₃ is predicted to have a barrier height of 66.8 kcal mol^-1. The predicted barrier heights are significantly lower than those obtained from Hartree-Fock estimates particularly for 1,3-sigmatropic shift and decomposition reaction of formamidine. Results of second order Moller-Plesset (MP2) studies also lead to the conclusion that inclusion of electron correlation decreases the barrier heights significantly for 1,3-sigmatropic shift and unimolecular decomposition of formamidine. Calculated equilibrium geometries, harmonic vibrational frequencies and relative energies are in excellent agreement with the results of MP2 studies.