title: DFT prediction of ground-state spin multiplicity of cyclobutane-1,3-diyls: notable effects of two sets of through-bond interactions.
abstract: DFT calculations (UB3LYP/6-31+G**) have been performed to predict the substituent effect on the ground-state spin-multiplicity and the singlet-triplet energy gap in cyclobutane-1,3-diyls, CB-DR. The ground state is calculated to be largely dependent on the substituents (X, Y) at the C2 and C4 positions. The substituent effects can be reasonably explained by the two sets of through-bond (TB) interactions which result from the coupling between the symmetric nonbonding molecular orbital (Psi(S)) and the C-X (Y) sigma and sigma* orbitals.
authors.affiliation: Department of Materials Chemistry & Frontier Research Center (HANDAI FRC), Graduate School of Engineering, Osaka University (HANDAI), Suita 565-0871, Osaka, Japan. abe@ap.chem.eng.osaka-u.ac.jp
authors.forename: Manabu
authors.initials: M
authors.lastname: Abe
authors.forename: Chizuko
authors.initials: C
authors.lastname: Ishihara
authors.forename: Masatomo
authors.initials: M
authors.lastname: Nojima