Model calculations of chemical interactions. Part 4.—Directed valency and analysis of intramolecular interactions with redundant basis sets

Abstract

Directed valency hybrids are obtained starting with a double-zeta-plus polarization basis set. The original atomic basis set (6-31G*/5d in our example) is split into a set of high-occupancy hybrids, a set of low-occupancy hybrids and a set of ‘pure’ polarization functions which, unlike hybrids, are not ‘assigned’ to specific molecular fragments (bonds, lone pairs, etc.) but to the molecule as a whole. Analysis of intramolecular interactions according to a procedure originally formulated for minimal basis sets reveals that these hybrids retain the essential features and meanings of those obtained in minimal basis sets, although they introduce the effects of electron delocalization from high- to low-occupancy hybrids of different fragments.