Ab initio calculations of substituent constants: A reinvestigation

A set of various substituent constants sigma(F), sigma(R), sigma(alpha), and sigma(chi) for 21 common substituents was recalculated according to the models of Marriott and Topsom which are based on ab initio calculations. Some inconsistencies in the original methods as to the use of molecular geometries and basis sets were eliminated and a few values of the original work were corrected. The set was extended by an additional 10 substituents derived from the amido and thioamido groups, with particular interest for QSAR. Comparison with standard experimental data confirmed the physical meaning and significance of the computational model for sigma(F), sigma(R), sigma(alpha), but not for sigma(chi). (C) 1997 Elsevier Science B.V.