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Intramolecular hydrogen bond in the hydroxycyclohexadienyl peroxy radicals
Author(s) -
Huang Mingqiang,
Wang Zhenya,
Yang Yong,
Hao Liqing,
Zhao Wenwu,
Gao Xiaoming,
Fang Li,
Zhang Weijun
Publication year - 2006
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.21209
Subject(s) - intramolecular force , antibonding molecular orbital , natural bond orbital , chemistry , radical , photochemistry , density functional theory , hydrogen bond , computational chemistry , atoms in molecules , crystallography , atomic orbital , molecule , stereochemistry , electron , organic chemistry , physics , quantum mechanics
The hydroxycyclohexadienyl peroxy radicals (HOC 6 H 6 O 2 ) produced from the reaction of OH‐benzene adduct with O 2 were studied with density functional theory (DFT) calculations to determine their characteristics. The optimized geometries, vibrational frequencies, and total energies of 2‐hydroxycyclohexadienyl peroxy radical II s and 4‐hydroxycyclohexadienyl peroxy radical III s were calculated at the following theoretical levels, B3LYP/6‐31G( d), B3LYP/6‐311G( d,p), and B3LYP/6‐311+G( d,p). Both were shown to contain a red‐shifted intramolecular hydrogen bond (OH … OH bond). According to atoms‐in‐molecules (AIM) analysis, the intramolecular hydrogen bond in the 2‐hydroxycyclohexadienyl peroxy radical II s is stronger than that one in 4‐hydroxycyclohexadienyl peroxy radical III s , and the former is the most stable conformation among its isomers. Generally speaking, hydrogen bonding in these radicals plays an important role to make them more stable. Based on natural bond orbital (NBO) analysis, the stabilization energy between orbitals is the main factor to produce red‐shifted intramolecular hydrogen bond within these peroxy radicals. The hyperconjugative interactions can promote the transfer of some electron density to the OH antibonding orbital, while the increased electron density in the OH antibonding orbital leads to the elongation of the OH bond and the red shift of the OH stretching frequency. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007