Structural Elucidation of N2O Clusters at Low Temperatures: Exemplary Framework Stabilized by π-Hole-Driven N···O and N···N Pnicogen Bonding Interactions.

Abstract

N2O is a classic prototype, in which central nitrogen is sufficiently electropositive with a positive potential of 20 kcal mol-1 in magnitude to qualify it as a possible pnicogen. This was applied to a test with N2O clusters using ab initio calculations in association with various molecular topographic tools. The structure of the energetically dominant and N2O dimer was in favor of a perpendicular geometry, where the central nitrogen atom of the N2O submolecule assumed a near 90° angle with the adjacent N═O and/or N═N moiety, which provides the affirmation of central nitrogen as a possible π-hole-driven pnicogen. The terminal nitrogen and oxygen atoms of N2O continue to act as conventional electron donors (Lewis bases) with a negative potential. Overall, predominant π-hole-driven N···O and N···N pnicogen bonding interactions were observed to stabilize N2O clusters. Furthermore, N2O clusters (dimers and trimers) were synthesized at low temperatures in an Ar matrix using molecular beam (effusive and supersonic expansion) experiments. The geometries of these clusters were characterized by probing infrared spectroscopy with corroboration from ab initio computational methods. In addition to our previously investigated nitromethane and nitrobenzene systems, N2O also makes it to a pnicogen bonder's club with the central nitrogen as a π-hole-driven pnicogen.