title: The contributions of through-bond interactions to the singlet-triplet energy difference in 1,3-dehydrobenzene.
abstract: Separation of the through-space (TS) from the through-bond (TB) interactions between the two atomic orbitals at C(1) and C(3) of 1,3-dehydrobenzene (1) has been achieved by carrying out ab initio, valence-bond, self-consistent-field (VBSCF) calculations. The results indicate that, at the CCSD(T)/cc-pVTZ optimized geometry of the singlet state of 1, the stabilization provided by TB interactions contributes 10% more than the stabilization provided by the TS interactions to the adiabatic singlet-triplet energy difference. The highest occupied MO of 1 contains a contribution from a hybrid AO at C(2), which has the same phase as the smaller lobes of the AOs at C(1) and C(3). Consequently, TB interactions in 1 increase with decreasing values of the C(1)-C(3) distance. The origin of this hybrid AO at C(2) and the contributions of hyperconjugation to TB and TS interactions in 1 are described and discussed.
authors.affiliation: Department of Chemistry and Center for Advanced Scientific Computing and Modeling, University of North Texas, 1155 Union Circle, #305070, Denton, Texas 76203-5070, USA.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Wei
authors.forename: David A
authors.initials: DA
authors.lastname: Hrovat
authors.forename: Yirong
authors.initials: Y
authors.lastname: Mo
authors.forename: Roald
authors.initials: R
authors.lastname: Hoffmann
authors.forename: Weston Thatcher
authors.initials: WT
authors.lastname: Borden
mesh_terms: D001554:Benzene / Q000737:chemistry*; D003198:Computer Simulation; D008956:Models, Chemical
chemical_list: D001554:Benzene