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Structural and theoretical analysis of 2‐chloro‐4‐nitroaniline and 2‐methyl‐6‐nitroaniline salts
Author(s) -
Medviediev Volodymyr,
Daszkiewicz Marek
Publication year - 2021
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229621001455
Subject(s) - nitroaniline , chemistry , hydrogen bond , nitro , triiodide , bromide , hydrogen , crystallography , crystal structure , crystal (programming language) , molecule , stereochemistry , inorganic chemistry , organic chemistry , programming language , alkyl , electrode , computer science , dye sensitized solar cell , electrolyte
The crystal structures of five new salts of 2‐chloro‐4‐nitroaniline (2Cl4na) and 2‐methyl‐6‐nitroaniline (2m6na) with inorganic acids, namely, 2‐chloro‐4‐nitroanilinium bromide, C 6 H 6 ClN 2 O 2 + ·Br − ( 1 ), 2‐chloro‐4‐nitroanilinium hydrogen sulfate, C 6 H 6 ClN 2 O 2 + ·HSO 4 − ( 2 ), 2‐methyl‐6‐nitroanilinium bromide, C 7 H 9 N 2 O 2 + ·Br − ( 3 ), 2‐methyl‐6‐nitroanilinium triiodide, C 7 H 9 N 2 O 2 + ·I 3 − ( 4 ), and 2‐methyl‐6‐nitroanilinium hydrogen sulfate, C 7 H 9 N 2 O 2 + ·HSO 4 − ( 5 ), were determined by single‐crystal X‐ray diffraction. Theoretical calculations of the relaxed potential energy surface (rPES) revealed that the energy barriers for the rotation of the nitro group for isolated H2Cl4na + and H2m6na + cations are 4.6 and 11.6 kcal mol −1 , respectively. The ammonium group and respective anions form hydrogen bonds which are the most important interactions and are arranged in zero‐ (in 3 ), one‐ (in 1 and 4 ) or two‐dimensional (in 2 and 5 ) networks. Hydrogen‐bonding patterns were analyzed by means of mathematical relationships between graph‐set descriptors and compared with previously reported nitroaniline salts. Hirshfeld surface analysis indicates that the nitro group plays a dominant role among the weak interactions, i.e. C—H…O(NO 2 ), NO 2 …π(Ar) and O(NO 2 )…π(NO 2 ). The frequency of the ν s NO 2 vibration is correlated with the type of interaction in which the NO 2 group is involved. Analysis of the ν s NO 2 band observed in the IR and Raman spectra allowed an assessment of its shift in the sequence (H2m6na)I 3 ( 4 ) < (H2m6na)HSO 4 ( 5 ) < (H2m6na)Br ( 3 ) < (H2Cl4na)Br ( 1 ) < (H2Cl4na)HSO 4 ( 2 ).