Features of the Pnictogen Bonds Formed by Neighboring Nitro Groups in Crystals

S.A Sobalev,Yu.V Matveychuk,E.V Bartashevich

doi:10.14529/chem190408

Abstract

Features of pnictogen O…N bonds were considered from the point of view of analyzing various geometric orientations of the neighboring nitro groups NO 2 …NO 2 observed in molecular crystals. The “idealized” orientation for a pnictogen bond, where the nucleophilic fragment of the atom O of one nitro group was directed to the electrophilic site of the atom N of the other one, and the “stacking” orientation, which was characterized by the parallel stacking of nitro groups, differ in the features of the electron density and electrostatic potential distribution between O and N atoms. The applied electronic criterion, obtained with the use of quantum chemical calculations with periodic boundary conditions, confirmed that for the considered O…N interactions the necessary condition for their classification as pnictogen bonds was met.

Highlights

Non-covalent bonds play an important role in formation of the physicochemical properties of a substance, and their study is important for predicting the properties of new multicomponent compounds with useful applications
With the “idealized” orientation, the region of concentration of the electron density of the O atom, which corresponds to a lower value of the molecular electrostatic potential, is directed to the region of the increased value of the molecular electrostatic potential (π-hole) (Fig. 2) of the N atom of the neighboring nitro group
Our analysis has shown that the electron density minimum, ρ(r)min, for all the studied O...N interactions is closer to the N atom, and the electrostatic potential minimum, φ(r)min, is located closer to the O atom (Fig. 3)

Summary

Introduction

Non-covalent bonds play an important role in formation of the physicochemical properties of a substance, and their study is important for predicting the properties of new multicomponent compounds with useful applications. On the basis of such factors as ∇2ρ(rO)min, dO(∇2ρmin), and d(φmin) on the O...N bond line we can identify the “idealized” orientation of neighboring nitro groups and, a stronger pnictogen O...N bond, relying only on the properties of electron density.

Results

Conclusion