title: The driving force for Π-bond localization and bond alternation in trisannelated benzenes.
abstract: To investigate the factors that may cause bond length alternation and π-bond localization in annelated benzenes, ab initio valence bond calculations were performed. The results reveal that the bond length alternation of annelated benzene is determined by the strain-induced hybridization change from the partially optimized geometries, in which the central benzene ring is constrained to a regular hexagon, to the equilibrium geometries rather than the previously recognized re-hybridization effect that the carbon atoms in the central ring are deviated from sp2hybridization. Meanwhile, the π-π interaction also provides a sort of driving force, which facilitates bond length alternation, which in turn magnifies π-bond localization. A subsequent potential energy curve study shows that σ-strain and π-π interactions have different mechanisms for the effect.
authors.affiliation: The State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China. zhhchen@xmu.edu.cn.
authors.forename: Xuhui
authors.initials: X
authors.lastname: Lin
authors.affiliation: The State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China. zhhchen@xmu.edu.cn.
authors.forename: Zhenhua
authors.initials: Z
authors.lastname: Chen
authors.affiliation: The State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China. zhhchen@xmu.edu.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Wu