Geiger David K, Parsons Dylan E
Department of Chemistry, State University of New York-College at Geneseo, 1 College Circle, Geneseo, NY 14454, USA.
Acta Crystallogr C Struct Chem. 2014 Jul;70(Pt 7):681-8. doi: 10.1107/S2053229614013485. Epub 2014 Jun 14.
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).
报道了4-硝基苯-1,2-二胺[C₆H₇N₃O₂, (I)]、2-氨基-5-硝基苯胺盐酸盐[C₆H₈N₃O₂(+)·Cl⁻, (II)]和2-氨基-5-硝基苯胺氢溴酸盐一水合物[C₆H₈N₃O₂(+)·Br⁻·H₂O, (III)]的结构，并描述了它们的氢键结构。(I)中硝基对位的胺基采用近似平面的几何构型，而间位胺基则明显呈金字塔形。在卤化氢盐(II)和(III)中，硝基间位的胺基被质子化。化合物(I)呈现出具有R₂(2)(14)和R₄(4)(20)环的褶皱片状氢键二维结构。这些片层通过额外的氢键连接，形成三维扩展结构。氢卤酸盐(II)在不对称单元中有两个通过假反演中心相关的化学式单元。主要的氢键相互作用涉及氯离子，并形成连接成梯链结构的R₄(2)(8)环。这些链通过N-H···Cl和N-H···O氢键连接形成平行于(010)的片层。在水合氢卤酸盐(III)中，溴离子与胺基和铵基形成氢键，形成R₄(2)(8)环。水作为双供体/单受体，与溴离子一起形成涉及硝基、胺基和铵基的氢键。结果是形成了由交替的R₅(5)(15)和R₆(4)(24)环组成的平行于(001)的片层。铵基的N-H···Br相互作用将这些片层连接起来，形成三维扩展结构。使用DFT和MP2计算得到的能量最小化结构与固态结构一致。与(II)和(III)一致，计算表明硝基间位胺基的质子化导致的结构比对位胺基质子化得到的结构稳定约1.5 kJ mol⁻¹。基于(I)和3-硝基苯-1,2-二胺(IV)[Betz & Gerber (2011). Acta Cryst. E67, o1359]的结构结果对单分子和氢键分子对进行的DFT计算用于估计三种观察到的基序的N-H···O(硝基)相互作用强度。发现所研究的分子对之间的氢键相互作用对应于20 - 30 kJ mol⁻¹。
