ISSN:
0192-8651
Keywords:
Computational Chemistry and Molecular Modeling
;
Biochemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Computer Science
Notes:
Ab initio MP2/6-31G*//MP2/6-31G* and semiempirical AM1 and PM3 calculations on a series of differently substituted α-oxo-ketenes are used to investigate E/Z-isomerism and rotational barriers in these molecules. Sterically crowded derivatives are found to exist solely as s-E conformers. The unusual stability of these derivatives thus can be attributed to their inability to adopt the s-Z conformation required for the normal α-oxo-ketene reactions. With respect to structures and energies, the PM3 method (especially in the case of highly crowded molecules) is found to be less reliable than AM1. Ab initio HF/3-21G and PM3 vibrational frequencies appear to be of sufficient accuracy for a distinction between s-Z and s-E conformers. In this respect, the AM1 method appears less reliable. © 1994 by John Wiley & Sons, Inc.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jcc.540150203
