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Nonadditivity of methyl group in single‐electron hydrogen bond of methyl radical‐water complex
Author(s) -
Li Qingzhong,
Zhu Hongjie,
An Xiulin,
Gong Baoan,
Cheng Jianbo
Publication year - 2008
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.21812
Subject(s) - chemistry , methyl group , methyl radical , natural bond orbital , hydrogen bond , radical , hydrogen atom , molecule , triple bond , bond length , single bond , computational chemistry , bond energy , hydrogen , crystallography , photochemistry , group (periodic table) , double bond , density functional theory , organic chemistry
The nonadditivity of methyl group in the single‐electron hydrogen bond of the methyl radical‐water complex has been studied with quantum chemical calculations at the UMP2/6‐311++G(2df,2p) level. The bond lengths and interaction energies have been calculated in the four complexes: CH 3 H 2 O, CH 3 CH 2 H 2 O, (CH 3 ) 2 CHH 2 O, and (CH 3 ) 3 CH 2 O. With regard to the radicals, tert‐butyl radical forms the strongest hydrogen bond, followed by iso‐propyl radical and then ethyl radical; methyl radical forms the weakest hydrogen bond. These properties exhibit an indication of nonadditivity of the methyl group in the single‐electron hydrogen bond. The degree of nonadditivity of the methyl group is generally proportional to the number of methyl group in the radical. The shortening of the C···H distance and increase of the binding energy in the (CH 3 ) 2 CHH 2 O and (CH 3 ) 3 CH 2 O complexes are less two and three times as much as those in the CH 3 CH 2 H 2 O complex, respectively. The result suggests that the nonadditivity among methyl groups is negative. Natural bond orbital (NBO) and atom in molecules (AIM) analyses also support such conclusions. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009