The influence of N⋯π pnicogen bonding in π-stacked parallel displaced geometry of nitrobenzene dimers: Evidence using matrix isolation infrared spectroscopy and ab initio computations

Abstract

The present study elucidates the preferential stabilization of parallel displaced geometry of nitrobenzene dimers by co-operative action of π…π interactions and ON⋯π pnicogen bonding. The homodimers have also been synthesized within Ne and Ar matrixes at cryogenic temperatures followed by their characterization using infrared spectroscopy. The significant contribution of short-range dispersion forces in stabilization of parallel-displaced geometries causes a concomitant rise in Pauli repulsion effects, owing to increased electron correlation. This destabilization is efficiently compensated for, by the added electrostatic effects due to the π-hole facilitated ON⋯π pnicogen bond. The directional determinism of the pnicogen bond proves pivotal in facilitating this co-operation with π…π interactions. These inferences have been obtained by a comparative computational analysis of the parallel displaced and ‘T-shaped’ geometries of the benzene homodimer, with their nitrobenzene analogues.