Sivakumar N, Muralidharan S, Chakkaravarthi G, Velmurugan D, Anbalagan G
Department of Physics, Presidency College, Chennai 600 005, India.
Department of Physics, Anna University, Chennai 600 025, India.
Acta Crystallogr Sect E Struct Rep Online. 2014 Sep 20;70(Pt 10):221-3. doi: 10.1107/S1600536814020583. eCollection 2014 Oct 1.
The title salt, 2C7H11N2 (+)·2C7H4NO4 (-)·3H2O, crystallized with two anions and two cations in the asymmetric unit, together with three water mol-ecules. Both 4-di-methyl-amino-pyridinium cations are protonated at their pyridine N atoms with the plane of the N(CH3)2 hetero atoms inclined to the pyridine ring by 4.5 (2) and 1.4 (2)°. In the 2-nitro-benzoate anions, the carboxyl and nitro groups are inclined to their respective benzene rings by 77.1 (3) and 20.0 (3)°, and 75.8 (2) and 20.9 (3)°. In the crystal, the anions are linked via O-H⋯O hydrogen bonds involving the water mol-ecules, forming chains along [100]. The cations are linked to these chains by N-H⋯O hydrogen bonds. The chains are linked via C-H⋯O hydrogen bonds and C-H⋯π and π-π inter-actions [inter-centroid distances range from 3.617 (1) to 3.851 (1) Å], forming a three-dimensional structure.
标题盐2C₇H₁₁N₂⁺·2C₇H₄NO₄⁻·3H₂O在不对称单元中结晶，含有两个阴离子、两个阳离子以及三个水分子。两个4-二甲基氨基吡啶鎓阳离子均在其吡啶N原子处质子化，N(CH₃)₂杂原子平面与吡啶环的夹角分别为4.5(2)°和1.4(2)°。在2-硝基苯甲酸根阴离子中，羧基和硝基与各自苯环的夹角分别为77.1(3)°和20.0(3)°，以及75.8(2)°和20.9(3)°。在晶体中，阴离子通过涉及水分子的O—H⋯O氢键相连，沿[100]方向形成链状结构。阳离子通过N—H⋯O氢键与这些链相连。这些链通过C—H⋯O氢键以及C—H⋯π和π–π相互作用（质心间距范围为3.617(1)至3.851(1) Å）相连，形成三维结构。
