A computational study on the stability of diaminocarbenes

The 1,2-H shift, 1,2-Me shift, and dimerization reactions of several diaminocarbenes have been studied using density functional theory and ab initio methods. It was observed that the activation energies (Ea) for the dimerization of diaminocarbenes are much smaller than those of 1,2-H shift, 1,2-Me shift and insertion. Dimerization is thus the most likely course of reaction for diaminocarbenes. The activation energies for the dimerization of diaminocarbenes which exhibit 6π-electron delocalization are larger than those of the non-aromatic ones. For cyclic diaminocarbenes there is a proportional relation between Ea and the singlet–triplet gap (ΔES–T), i.e., Ea of dimerization is larger as ΔES–T increases.