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Pseudo Jahn–Teller origin tracking for symmetry breaking in halogenabenzene: How can a bird fly?
Author(s) -
Wang Ya,
Liu Yang,
Zheng Xiaonan
Publication year - 2018
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.25704
Subject(s) - jahn–teller effect , planar , vibronic coupling , valence (chemistry) , chemistry , excited state , symmetry breaking , electronic structure , molecule , coupling (piping) , molecular physics , ground state , valence bond theory , physics , atomic physics , computational chemistry , chemical physics , ion , quantum mechanics , materials science , molecular orbital , computer graphics (images) , computer science , metallurgy
The cyclic iodabenzene molecule (CH) 5 I was first introduced and characterized as planar configuration and zwitterionic valence structure by Glukhovtsev in 1991. Recently, it caused researchers' great interest due to the theoretical discovery of a stable bird‐like structure by Hoffmann et al. in 2017 which has similar electronic structure and charge distribution as well‐known Meisenheimer complex C 6 H7 − . Inspired by this, we continue to tell the halogenabenzene story by revealing the origin of the bird‐like structure and understanding how the electronic behavior affects the geometrical symmetry for a molecule. By combining the Pseudo Jahn–Teller effect (PJTE) theory with the ab initio calculations for halogenabenzenes (CH) 5 X (X = F, Cl, Br, I) and C 6 H7 − , it is illustrated that the vibronic coupling of 1 A 1 ground state and 1 B 1 excited states with C 2v planar structure along the out‐of‐plane b 1 distortion triggers the symmetry breaking of planar configuration to form a preferred bird‐like structure. This interpretation can be also applied to explain their different stabilization energies by analyzing numerically the energy gaps of coupled electronic states and PJTE vibronic coupling parameters. Taking use of the PJTE formulation above, we also tracked the origin of restoring to be planar for (CH) 5 X 2+ cation, as well as their isoelectronic species (CH) 5 O + and (CH) 5 N, and suggests an effective strategy to stabilize the planar configuration for halogenabenzenes.