Understanding the geometry and [3 + 2] cycloadditions of nitrile imine in terms of molecular electron density theory

Abstract

Nitrile imine has been classified as carbenoid type three atom component (TAC) by CCSD(T) calculations. [3+2] cycloaddition (32CA) reactions of nitrile imine to a set of olefins is studied in this report in terms of global electron density transfer (GEDT), Bonding evolution theory (BET) and Quantum theory of atoms in molecules (QTAIM) analyses at B3LYP and MPWB1K levels. The reactions are non-polar showing non-covalent interactions and hence GEDT doesn't make the reaction feasible by inducing significant electrophilic-nucleophilic interaction between reactants as occurs in case of polar processes. Mutual penetration of forming bonds to the Van-der Waals' surface was reproduced in asymmetry indices at the transition states. BET and QTAIM study confirmed initial rupture of olefinic bond, followed by the formation of pseudoradical centres and subsequently the bond-formation processes.