Density Functional Theory Study of the Reactivities of Perimidine-Based Carbene Analogues of the Group 14 Elements

Abstract

The potential energy surfaces for the chemical reactions of group 14 carbenes have been studied using density functional theory (B3LYP/LANL2DZ). Five group 14 carbene species containing three six-membered rings, perimidine-E, where E = C, Si, Ge, Sn, and Pb, have been chosen as model reactants in this work. Also, four kinds of chemical reaction, C−H bond insertion, alkene cycloaddition, O−H bond insertion, and dimerization, have been used to study the chemical reactivities of these group 14 carbenoids. The present theoretical investigations suggest that the relative carbenic reactivity decreases in the order C > Si > Ge > Sn > Pb. That is, the heavier the group 14 atom (E), the less reactive are its carbene compounds with respect to chemical reaction. Also, our theoretical findings suggest that all the perimidine-E carbenes are isolable at room temperature, since they are quite inert to chemical reactions, except for reaction with water. Furthermore, the group 14 carbene singlet−triplet energy splitting, as described in the configuration mixing model attributed to the work of Pross and Shaik, can be used as a diagnostic tool to predict their reactivities. The results obtained allow a number of predictions to be made.