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Strong effect of methyl group on the strength of ionic hydrogen bond between C 2 H 2 and H 3 O +
Author(s) -
An Xiulin,
Li Qingzhong
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.21882
Subject(s) - chemistry , hydrogen bond , ionic bonding , methyl group , proton , hydrogen , acceptor , low barrier hydrogen bond , solvent , bond energy , computational chemistry , crystallography , group (periodic table) , ion , molecule , organic chemistry , physics , quantum mechanics , condensed matter physics
The effect of methyl group on the strength of the ionic hydrogen bond between C 2 H 2 and H 3 O + has been studied with quantum chemical calculations at the UMP2/6‐311++G(d,p) level. The presence of a methyl group in the proton acceptor results in an energetic increase of 6.02 kcal/mol, increased by about 39%, whereas that in the proton donor leads to an energetic decrease of 2.18 kcal/mol, decreased by 14%. The charge analyses indicate that the methyl group in the proton acceptor is electron‐donating and that in the proton donor is electron‐withdrawing. The former plays a positive contribution to the formation of ionic hydrogen bond and the latter plays a negative contribution to the formation of ionic hydrogen bond. The weakening effect of solvent on the role of methyl group in the ionic hydrogen bond has also been studied at the UB3LYP/6‐311++G(d,p) level. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009