Theoretical study of conformational changes in simple hydrazones

Abstract

An ab initio MO study was carried out in order to predict the conformational properties of C-substituted hydrazones. The order of stability found for the stereoisomers of these compounds changes when a methyl group bonded to the imine carbon atom is replaced by fluorine, the Z-form being more stable in the latter case. The E⇌Z isomerization process turns out to have an inversion pathway, and the energy barrier depends on the substitution at the carbon atom. The mechanism of inversion of the amino nitrogen, which is only slightly distorted from planarity, requires small activation energies which differ in the two stereoisomers of the compounds examined.