Hydrogen bonding in 4-nitrobenzene-1,2-diamine and two hydrohalide salts

Abstract

The structures of 4-nitrobenzene-1,2-diamine [C6H7N3O2, (I)], 2-amino-5-nitroanilinium chloride [C6H8N3O2(+)·Cl(-), (II)] and 2-amino-5-nitroanilinium bromide monohydrate [C6H8N3O2(+)·Br(-)·H2O, (III)] are reported and their hydrogen-bonded structures described. The amine group para to the nitro group in (I) adopts an approximately planar geometry, whereas the meta amine group is decidedly pyramidal. In the hydrogen halide salts (II) and (III), the amine group meta to the nitro group is protonated. Compound (I) displays a pleated-sheet hydrogen-bonded two-dimensional structure with R2(2)(14) and R4(4)(20) rings. The sheets are joined by additional hydrogen bonds, resulting in a three-dimensional extended structure. Hydrohalide salt (II) has two formula units in the asymmetric unit that are related by a pseudo-inversion center. The dominant hydrogen-bonding interactions involve the chloride ion and result in R4(2)(8) rings linked to form a ladder-chain structure. The chains are joined by N-H···Cl and N-H···O hydrogen bonds to form sheets parallel to (010). In hydrated hydrohalide salt (III), bromide ions are hydrogen bonded to amine and ammonium groups to form R4(2)(8) rings. The water behaves as a double donor/single acceptor and, along with the bromide anions, forms hydrogen bonds involving the nitro, amine, and ammonium groups. The result is sheets parallel to (001) composed of alternating R5(5)(15) and R6(4)(24) rings. Ammonium N-H···Br interactions join the sheets to form a three-dimensional extended structure. Energy-minimized structures obtained using DFT and MP2 calculations are consistent with the solid-state structures. Consistent with (II) and (III), calculations show that protonation of the amine group meta to the nitro group results in a structure that is about 1.5 kJ mol(-1) more stable than that obtained by protonation of the para-amine group. DFT calculations on single molecules and hydrogen-bonded pairs of molecules based on structural results obtained for (I) and for 3-nitrobenzene-1,2-diamine, (IV) [Betz & Gerber (2011). Acta Cryst. E67, o1359] were used to estimate the strength of the N-H···O(nitro) interactions for three observed motifs. The hydrogen-bonding interaction between the pairs of molecules examined was found to correspond to 20-30 kJ mol(-1).

Structural, theoretic and spectroscopic analysis of 2-methyl-5-nitroaniline salts with various inorganic acids

“…The ammonio group forms charge-assisted hydrogen bonds, whereas the other substituents are involved in weak intermolecular interactions stabilizing the crystal structure. Literature data and our previous work showed a high tendency for nitroanilinium salts to create two-dimensional hydrogen-bonding networks (Daszkiewicz, 2013a;Geiger & Parsons, 2014;Marchewka et al, 2003). These two-dimensional hydrogen-bonding networks are connected to each other by interactions based on the nitro group, such as weak C-HÁ Á ÁO hydrogen bonds or various NO2 Á Á Á NO2 or NO2 Á Á Á Ar contacts (Daszkiewicz, Montazerozohori et al, 2015;Sikorski & Trzybiń ski, 2013).…”

How does the combination of the nitro group and fluorine atoms affect the (co)crystallization behaviour of arylenediamines?

“…Nitro-substituted aromatic amines are capable of forming extended H-bonded supramolecular structures. 16,17 There are several H-bond acceptors in molecules A-D, with the oxygen atoms of a NO 2 group being the most effective. However, N amino and F atoms, due to their lone electron pairs, can also serve as H-acceptors to form N-H⋯N amino and N-H⋯F H-bonds.…”

“…The presence of the two H-bond acceptors (O nitro ) makes nitro substituted aromatic amines capable of forming extended H-bonded supramolecular structures in one, two, or three dimensions (see, for example, ref. 16 and 17). The extension of the π-system in the co-former due to NO 2 + aromatic ring conjugation enhances π-stacking in the crystals, 17–20 making it a powerful structure stabilizing factor.…”

“…16 and 17). The extension of the π-system in the co-former due to NO 2 + aromatic ring conjugation enhances π-stacking in the crystals, [17][18][19][20] making it a powerful structure stabilizing factor. Nitrobenzene derivatives are widely used to make various functional materials such as molecular crystals exhibiting nonlinear optical properties, 21,22 solid-state thermochromic materials, 20,23 sensors for chiroptical analysis, 24 dyes and luminophores.…”