External electric field effects on the σ-hole and lone-pair hole interactions of group V elements: a comparative investigation

sigma-hole and lone-pair (lp) hole interactions of trivalent pnicogen-bearing (ZF(3)) compounds were comparatively scrutinized, for the first time, under field-free and external electric field (EEF) conditions. Conspicuously, the sizes of the sigma-hole and lp-hole were increased by applying an EEF along the positive direction, while the sizes of both holes decreased through the reverse EEF direction. The MP2 energetic calculations of ZF(3)MIDLINE HORIZONTAL ELLIPSISFH/NCH complexes revealed that sigma-holes exhibited more impressive interaction energies compared to the lp-holes. Remarkably, the strengths of sigma-hole and lp-hole interactions evolved with the increment of the positive value of the considered EEF; i.e., the interaction energy increased as the utilized EEF value increased. Unexpectedly, under field-free conditions, nitrogen-bearing complexes showed superior strength for their lp-hole interactions than phosphorus-bearing complexes. However, the reverse picture was exhibited for the interaction energies of nitrogen- and phosphorus-bearing complexes interacting within lp-holes by applying the high values of a positively directed EEF. These results significantly demonstrate the crucial influence of EEF on the strength of sigma-hole and lp-hole interactions, which in turn leads to an omnipresent enhancement for variable fields, including biological simulations and material science.