The Cr(III) and Ca(II) complexes (dmpH)[Cr(pydc)₂]•H₂O (1) and [Ca₂(pydc)₂(H₂O)₆].2pydcH₂ (2) were synthesized by reaction of 2,9-dimethyl-1,10-phenanthroline (dmp) and pyridine-2,6-dicarboxylic acid (pydcH₂) with Cr(NO₃)₃ and Ca(NO₃)₂, respectively, and characterized using IR spectroscopy, single crystal X-ray diffraction method and solution studies. The space group and crystal system of these two compounds are P2 ₁/c and monoclinic. The crystal dimensions are a = 9.785(3) Å, b = 25.671(4) Å, c = 9.3402(16) Å, β = 90.790(17)° for (1) and a = 9.1319(4) Å, b = 14.8430(8) Å, c = 12.2449(7) Å, β = 98.227(5)° for (2). In complex (1), a water molecule presents in the crystal packing, linking the anionic and cationic fragments together by hydrogen bonding and thus increases the stabilization of crystal lattices. In complex (2), the coordinated water molecules relate each dimer to adjacent dimers forming infinite molecular ribbons by strong hydrogen bondings. Hydrogen bonding and ion pairing play an important role in stabilizing these crystals. The complexation reactions of pydc, dmp and pydc+dmp with Cr³⁺ and Ca²⁺ ions in aqueous solution were investigated by potentiometric pH titrations and the equilibrium constants for all major complexes formed were evaluated.

中文翻译：

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从二吡啶甲酸获得的铬（III）和钙（II）配合物：合成，表征，X射线晶体结构和溶液研究

Cr（III）和Ca（II）络合物（dmpH）[Cr（pydc）₂ ]•H ₂ O（1）和[Ca ₂（pydc）₂（H ₂ O）₆ ] .2pydcH ₂（2）为由（pydcH 2,9-二甲基-1,10-菲咯啉（DMP）和吡啶-2,6-二羧酸的反应合成₂）用的Cr（NO ₃）₃和Ca（NO ₃）₂，分别与特征使用红外光谱，单晶X射线衍射法和溶液研究。这两种化合物的空间群和晶体系统为P2 ₁/ c和单斜。晶体尺寸为a = 9.785（3）Å，b = 25.671（4）Å，c = 9.3402（16）Å，（1）的β= 90.790（17）° ，a = 9.1319（4）Å，b = 14.8430（8）埃，c ^ = 12.2449（7）α，β= 98.227（5）°，（2）。在配合物（1）中，水分子存在于晶体堆积中，通过氢键将阴离子和阳离子片段连接在一起，从而增加了晶格的稳定性。在复杂（2），配位的水分子通过强氢键将每个二聚体与相邻的二聚体联系起来，形成无限的分子带。氢键和离子对在稳定这些晶体中起重要作用。含Cr pydc，DMP和pydc + DMP的络合反应³⁺和Ca ²⁺离子在水溶液中，通过电位研究p ħ滴定和平衡常数形成的所有主要复合物进行了评价。