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Internal rotational potential in α,α‐dichlorotoluene
Author(s) -
Schaefert Ted,
Penner Glenn H.
Publication year - 1985
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1250160514
Subject(s) - cndo/2 , conformational isomerism , chemistry , potential energy , molecular mechanics , benzene , computational chemistry , bond length , hydrogen , internal rotation , hydrogen bond , rotation (mathematics) , carbon fibers , molecular physics , crystallography , molecule , atomic physics , molecular dynamics , materials science , physics , geometry , organic chemistry , mechanical engineering , mathematics , composite number , engineering , composite material
Whereas carbon‐hydrogen stretching frequencies and some CNDO/2 and molecular mechanics calculations suggest a double minimum potential for the rotation about the sp 2 ‐sp 3 carbon‐carbon bond in α,α‐dichlorotoluene, an extensively geometry optimized STO 3G MO computation implies a two‐fold (single minimum) potential of 11.6±0.1 kJ mol −1 and that in the conformer of low energy the CH bond in the side‐chain prefers the benzene plane. Fully relaxed molecular mechanics procedures also indicate a two‐fold barrier. A value of 9.2±1.3 kJ mol −1 had been derived from long‐range spin‐spin coupling constants. There is a need for an independent determination of the shape of the internal potential.