Intermolecular interactions in 2-methyl-3-nitroanilinium nitrate, sulphate and dihydrogen phosphate in a view of topological approach and vibrational spectra

Crystal structure of three new salts of 2-methyl-3-nitroaniline with inorganic acids, (H2m3na)NO3 (1), (H2m3na)(2)SO4 (2), (H2m3na)H2PO4 (3) are determined by single-crystal X-ray diffraction. Theoretical calculations of the relaxed potential surface reveal non-planarity of the nitro group towards benzene ring for the structure of global minimum, which is atypical conformation amongst nitroanilines. The ammonio group and respective anions are engaged in formation of layered hydrogen bonding network, which is analysed by means of graph-set approach and construction of hydrogen bonding patterns is presented by algebraic relations between graph-set descriptors. Analysis of the IR spectra allowed to assess a strength of hydrogen bonds in the sequence (H2m3na)NO3 < (H2m3na)(2)SO4 < (H2m3na)H2PO4. A frequency of the nu sNO2 vibration was correlated with the type of interaction of the NO2 group. In the nitrate salt, the nitro group is engaged in C-H center dot center dot center dot O hydrogen bond and nu sNO2 band was observed at 1343 cm(-1). This band is blue-shifted up to 1362 and 1359 cm(-1) for compounds 2 and 3, respectively. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

The crystal structures of three new salts of 2-methyl-3-nitroaniline with inorganic acids have been determined by single-crystal X-ray diffraction. The nitro group in compounds 2 and 3 show a higher nusNO2 vibration frequency compared to the nitrate salt, indicating different types of interactions.