Radical anions of carbenes and carbene homologues. DFT study and preliminary experimental results

Abstract

In the course of exploring the electronic properties and chemistry of stable non-annelated and annelated heterocyclic carbenes and carbene analogues (silylenes, germylenes and nitrenium ions), we investigated ground state configurations of such structures as well as their one-electron reduction by means of ab initio calculations. We used a DFT approach, which proved to be reliable for obtaining the geometries of the ground state molecules and was thus employed for all calculations. The compounds investigated are presented in Scheme 2. Injection of one electron into these molecules leads to the formation of radical anions, except for with cation 4a, which gives a neutral radical. For all molecules, ground states are singlet states and comparison has been made in terms of geometrical parameters with known experimental structures and results obtained at the MP2 level of calculation. These results, along with experimental data on the reduction of carbenes, nitrenium ions and germylenes obtained by cyclic voltammetry, give some clues about their stability, properties and potential redox activity.