Inter- and Intramolecular Interactions in Crystalline 2‑Nitrobenzoic AcidAn Experimental and Theoretical QTAIM Analysis

We have quantified the inter- and intramolecular interactions in crystalline 2-nitrobenzoic acid from QTAIM analysis of the topology of the electron density distribution obtained from both a low temperature (20 K) X-ray diffraction experiment and from theoretical calculations. The covalent bonds have been characterized by the properties at their (3,–1) bond critical points; in particular the nature of the aromatic/nitro group C–N bond is discussed. All noncovalent bonds of the type O···H (both strong and weak), C···C, O···O, and O···C have also been characterized. Intermolecular interactions may be roughly divided into three types, the formation of a classical carboxylic acid hydrogen bonded dimer, an unusual ribbon of O···O interactions parallel to a, and a number of predominantly O···H interactions perpendicular to a. Integrated atomic charges (in particular for the acidic hydrogen, ∼+0.6) and the derived molecular dipole moment are reported.