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Asymmetry in methyl group of ethane during internal rotation: Ab initio study
Author(s) -
Mastryukov Vladimir S.,
Samdal Svein
Publication year - 1998
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/(sici)1096-987x(19980730)19:10<1141::aid-jcc3>3.0.co;2-m
Subject(s) - dihedral angle , methyl group , chemistry , ab initio , torsion (gastropod) , internal rotation , bond length , asymmetry , computational chemistry , group (periodic table) , molecular geometry , moiety , molecular physics , crystallography , physics , stereochemistry , quantum mechanics , molecule , crystal structure , hydrogen bond , organic chemistry , mechanical engineering , engineering , medicine , surgery
Computational studies of the minimum energy pathway for internal rotation of a methyl group are often made by constraining one dihedral angle at a sequence of values and optimizing all other parameters. When this is done, the methyl group adopts an asymmetric configuration at intermediate values of the torsion angle, with unequal bond lengths, bond angles, and torsion angles, even though the moiety against which it is rotating is another methyl group. The potential surface leading to this phenomenon is investigated using Hartree–Fock SCF calculations at the 6‐31G* and 6‐311G** levels and the detailed structural behavior of the methyl group during the course of the internal rotation is examined. It is shown that the nature of the constraint governs the resulting deformation of the methyl group symmetry. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 1141–1145, 1998