ISSN:
0020-7608
Keywords:
Computational Chemistry and Molecular Modeling
;
Atomic, Molecular and Optical Physics
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Ab initio and INDO LCBO-MO calculations are carried out on glyoxal, 1,3-butadiene, and acrolein in order to analyze the qualitative failure of INDO-like methods to describe conformation energies in these molecules. Following the method of Brunck and Weinhold for ethanelike systems we identify the principal bond-antibond interactions contributing to the glyoxal barrier, their dependence on dihedral angle and substituent, and their relative magnitudes as calculated by ab initio and INDO SCF-MO theory. We find a gross disparity in the INDO representation of π* interactions which leads to a grossly exaggerated estimate of the stability of gauche conformers in these molecules. These findings appear to have serious implications for the applicability of INDO-like theories to conformational problems in π-bonded molecules, including those of biological interest.
Additional Material:
6 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/qua.560190509
Permalink
