The electronic structures of non-Kekulé isoelectronic molecules 1,3,5-trimethylenebenzene (TMB) and 1,3,5-triaminobenzene trication (TAB3+ are discussed by means of the ab initio molecular orbital (MO) method in the unrestricted Hartree-Fock scheme. In TMB the quartet state with planar D3h geometry is predicted to lie 26 kcal/mol below the lowest doublet state with a planar C2v geometry in which one of the methylene groups has a longer CC bridge bond connecting the phenyl ring. Moreover, in TAB3+ the quartet state with planar D3h geometry also lies 17 kcal/mol below the lowest doublet state with an orthogonal geometry where one of the amino groups is twisted out of the molecular plane. These quartet ground states result from the nearly threefold-degenerate orbitals consisting of the nonbonding MOs.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry