Single crystals of two new bimetallic oxalate compounds with the formula [ACr(C₂O₄)₂(H₂O)₄]_n (A = Li or Na), namely catena‐poly[[diaqualithium(I)]‐μ‐oxalato‐κ⁴O¹,O²:O^1′,O^2′‐[diaquachromium(III)]‐μ‐oxalato‐κ⁴O¹,O²:O^1′,O^2′], (I), and catena‐poly[[diaquasodium(I)]‐μ‐oxalato‐κ⁴O¹,O²:O^1′,O^2′‐[di‐aquachromium(III)]‐μ‐oxalato‐κ⁴O¹,O²:O^1′,O^2′], (II), have been synthesized, characterized and their crystal structures elucidated by X‐ray diffraction analysis and compared. The compounds crystallize in the monoclinic space group C2/m for (I) and in the triclinic space group P for (II); however, they have somewhat similar features. In the asymmetric unit of (I), the Li and Cr atoms both have space‐group‐imposed 2/m site symmetry, while only half of the oxalate ligand is present and two independent water molecules lie on the mirror plane. The water O atoms around the Li atom are disordered over two equivalent positions separated by 0.54 (4) Å. In the asymmetric unit of (II), the atoms of one C₂O₄²⁻ ligand and two independent water molecules are in general positions, and the Na and Cr atoms lie on an inversion centre. Taking into account the symmetry sites of both metallic elements, the unit cells may be described as pseudo‐face‐centred monoclinic for (I) and as pseudo‐centred triclinic for (II). Both crystal structures are comprised of one‐dimensional chains of alternating trans‐Cr(CO)₄(H₂O)₂ and trans‐A(CO)₄(H₂O)₂ units μ₂‐bridged by bis‐chelating oxalate ligands. The resulting linear chains are parallel to the [101] direction for (I) and to the [11] direction for (II). Within the two coordination polymers, strong hydrogen bonds result in tetrameric R₄⁴(12) synthons which link the metal chains, thus leading to two‐dimensaional supramolecular architectures. The two structures differ from each other with respect to the symmetry relations inside the ligand, the role of electrostatic forces in the crystal structure and the molecular interactions of the hydrogen‐bonded networks. Moreover, they exhibit the same UV–Vis pattern typical of a Cr^III centrosymmetric geometry, while the IR absorption shows some differences due to the oxalate‐ligand conformation. Polymers (I) and (II) are also distinguished by a different behaviours during the decomposition process, the precursor (I) leading to the oxide LiCrO₂, while the residues of (II) consist of a mixture of sodium carbonate and Cr^III oxide.

中文翻译：

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ACr（C2O4）2（H2O）4（A = Li或Na）：两种具有不同氢键网络的低维新配位聚合物。

与下式的两个新的双金属草酸盐化合物单晶[甲的Cr（C ₂ Ò ₄）₂（H ₂ O）₄ ] _Ñ（甲= Li或Na），即连锁-聚[[diaqualithium（I）] - μ -oxalato-κ ⁴ ø ¹，Ò ²：Ô ^1' ，ö ^2' - [diaquachromium（III）] - μ-草酸-κ ⁴ ø ¹，Ò ²：Ô ^1' ，Ò ^2' ]，（我）和系列-聚[[diaquasodium（I）] - μ-草酸-κ ⁴ ø ¹，Ò ²：Ô ^1'，Ö ^2' - [二- aquachromium（III）] - μ-草酸-κ ⁴ ø ¹，Ò合成了²：O ^1'，O ^2' ]，（II），并通过X射线衍射分析阐明了它们的晶体结构，并进行了比较。对于（I），化合物在单斜空间群C 2 / m中结晶；对于（II），在三斜晶空间群P中结晶。）; 但是，它们具有相似的功能。在（I）的不对称单元中，Li和Cr原子均具有空间基团强加的2 / m位置对称性，而草酸配体仅存在一半，两个独立的水分子位于镜面上。Li原子周围的水O原子在相隔0.54（4）的两个等效位置上无序。在（II）的不对称单元中，一个C ₂ O ₄ ^2-配体的原子和两个独立的水分子处于一般位置，并且Na和Cr原子位于反型中心。考虑到两种金属元素的对称位点，晶胞可以描述为（I）和（II）的伪中心三斜线。两者的晶体结构由交替的一维链的反式-Cr（CO）₄（H ₂ O）₂和反式-甲（CO）₄（H ₂ O）_2个单位μ ₂通过双-螯合配体草酸盐-bridged 。所得的线性链对于（I）平行于[101]方向，对于（II）平行于[11 ]方向。在两个配位聚合物中，强氢键导致四聚体R ₄ ⁴（12）连接金属链的合成子，从而导致二维超分子结构。两种结构在配体内部的对称关系，静电力在晶体结构中的作用以及氢键网络的分子相互作用方面互不相同。此外，它们表现出与Cr ^III中心对称几何形状相同的相同的UV-Vis图案，而由于草酸盐-配体的构象，红外吸收显示出一些差异。聚合物（I）和（II）的区别还在于在分解过程中行为不同，前体（I）生成氧化物LiCrO ₂，而（II）的残基）由碳酸钠和Cr ^III氧化物的混合物组成。