Aghabozorg Hossein, Roshan Leila, Firoozi Najmeh, Ghadermazi Mohammad, Bagheri Sara
Acta Crystallogr Sect E Struct Rep Online. 2008 Aug 30;64(Pt 9):m1208-9. doi: 10.1107/S1600536808027347.
The reaction of chromium(III) nitrate hexa-hydrate, pyridine-2,6-diamine and 4-hydroxy-pyridine-2,6-dicarboxylic acid in a 1:2:2 molar ratio in aqueous solution resulted in the formation of the title compound, (C(5)H(8)N(3))[Cr(C(7)H(3)NO(5))(2)]·2H(2)O or (pydaH)[Cr(hypydc)(2)]·2H(2)O (where pyda is pyridine-2,6-diamine and hypydcH(2) is 4-hydroxy-pyridine-2,6-dicarboxylic acid). Each Cr(III )atom is hexa-coordinated by four O and two N atoms from two (hypydc)(2-) fragments, which act as tridentate ligands, in a distorted octa-hedral geometry. The O-Cr-O-C torsion angles between the two planes of the (hypydc)(2-) fragments [-99.81 (17) and 97.77 (17)°] indicate that these two units are almost perpendicular to one another. In the crystal structure, extensive O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds with D⋯A distances ranging from 2.560 (2) to 3.279 (3) Å, ion pairing, C-O⋯π [O⋯π = 3.166 (2) Å] and π-π stacking inter-actions between (hypydc)(2-) and (pydaH)(+) rings [with a centroid-centroid distance of 3.3353 (14) Å] contribute to the formation of a three-dimensional supra-molecular structure.
硝酸铬（III）六水合物、吡啶-2,6-二胺和4-羟基吡啶-2,6-二羧酸以1:2:2的摩尔比在水溶液中反应，生成了标题化合物（C(5)H(8)N(3))[Cr(C(7)H(3)NO(5))(2)]·2H(2)O或（pydaH)[Cr(hypydc)(2)]·2H(2)O（其中pyda为吡啶-2,6-二胺，hypydcH(2)为4-羟基吡啶-2,6-二羧酸）。每个Cr(III)原子由来自两个（hypydc)(2-)片段的四个O原子和两个N原子以六配位方式配位，这两个（hypydc)(2-)片段作为三齿配体，形成扭曲的八面体几何构型。（hypydc)(2-)片段的两个平面之间的O-Cr-O-C扭转角[-99.81 (17)°和97.77 (17)°]表明这两个单元几乎相互垂直。在晶体结构中，广泛的O-H⋯O、N-H⋯O和C-H⋯O氢键（D⋯A距离范围为2.560 (2)至3.279 (3) Å）、离子对、C-O⋯π [O⋯π = 3.166 (2) Å]以及（hypydc)(2-)和（pydaH)(+)环之间的π-π堆积相互作用[质心-质心距离为3.3353 (14) Å]有助于形成三维超分子结构。
