Comparison of hydrogen bonds and diverse weak interactions of the nitro group in 2-methyl-4- nitroanilinium nitrate, bisulfate and two hexafluoridosilicates: elementary graph-set approach

摘要

Crystal structures of (H2m4na)NO_3 (1), (H2m4na)HSO_4 (2), (H2m4na)_2SiF_6 (3) and (H2m4na)_2SiF_6?2H_2O (4), where 2m4na = 2-methyl-4-nitroaniline, are presented. Two layers of interactions occur in the structures, N—H…O/F hydrogen bonds and interactions with the nitro group. Although diverse, hydrogen-bonding patterns are compared with each other by means of interrelations among elementary graph-set descriptors and descriptors of hydrogen-bonding patterns. Using mathematical relations, the gradual expansion of the ring patterns was shown in the crystal structures. Parallel and perpendicular arranged nitro groups form weak π(N)_(NO2)…π(O)_(NO2) and π(N)_(NO2)…O_(NO2) interactions, respectively. The π_(NO2)…π_(ring) interaction has an impact to the stabilization of parallel oriented nitro groups. Generally, weak interactions constructed by the nitro group occur in the studied crystals as follows: π(N)_(NO2)…π(O)_(NO2), π_(ring)…π_(ring), C—H…O (1); π(N)_(NO2)…π(O)_(NO2), π(N)_(NO2)…O_(NO2) (2); π(N)_(NO2)…π(O)_(NO2), π(N)_(NO2)…ONO2 (3); C—H…O (4).