Trigonal Bipyramidal and Related Molecules of the Main Group Elements: Investigation of Apparent Exceptions to the VSEPR Model through the Analysis of the Laplacian of the Electron Density

Abstract

Topological analyses of the charge density (p) and the Laplacian of the charge density (⊇ 2 p) for molecules of the types AF 4 E (A=P, S, Cl; E=a lone pair of electrons) and YSF 4 (Y=O, NH, CH 2 ) are presented. Examination of the relative sizes and shapes of bonding and nonbonding valence shell charge concentrations (VSCC's), which are made evident from the study of ⊇ 2 p, enables the geometrical features of these molecules to be understood and shows that they are in agreement with the concepts of the VSEPR model of molecular geometry