INFLUENCE OF HYBRIDIZATION DISPLACEMENT CHARGE ON THE DESCRIPTION OF ELECTROSTATIC POTENTIALS OF MOLECULES WITH MULTIPLE ELECTROPHILIC SITES

摘要

The importance of the hybridization displacement charge (HDC) in describing molecular electrostatic potential (MEP) maps was demonstrated by studying six molecules; pyrazine N-oxide, para-nitropyridine, 5-nitropyrimidine, 3-nitropyridazine, N-2, and N2O. It is shown that continuously distributed HDC-corrected Lowdin charges reproduce the MEP features of these molecules, most of which have competing electrophilic sites, in agreement with ab initio results. Further, it is found that for homonuclear diatomic molecules MEP minima can be located properly using HDC-corrected Lowdin (or HDC-corrected Mulliken) continuously distributed charges, but these features cannot be obtained using the conventional Lowdin (or Mulliken) charges. It was shown that the order of molecular electric field (MEF) values near the different electrophilic sites becomes changed when one moves away from the molecules. Thus, pyridine-type nitrogen atoms are the preferred binding sites close to the molecules, while at large distances, effects of oxygen atoms of the NO groups become dominant. (C) 1997 John Wiley & Sons, Inc. [References: 27]