基于2,3-二羟基丁二酸新配位方式构建的新颖双U形四核铜配合物[Cu4(dhbd)2(dpphen)4•2H2O]•8H2O

利用水热法合成了标题配合物Cu₄(dhbd)₂(dpphen)₄?2H₂O]?8H₂O(H4dhbd＝2,3-二羟基丁二酸, dpphen＝4,7-二苯基-1,10-邻菲咯啉), 通过元素分析、红外光谱、热分析、X射线单晶衍射等技术对其进行了表征. 晶体结构分析表明, 由于水的配位阻断, 2,3-二羟基丁二酸根仅通过单羟基氧桥联两个U形双核亚单元形成具有一个对称中心的双U形四核结构, 其中U型亚单元包含晶体学上不对称的2个Cu(II)原子、1个2,3-二羟基丁二酸根(dhbd)、2个4,7-二苯基-1,10-邻菲咯啉(dpphen)和1个配位H₂O分子. 毗邻的四核单元通过配位H2O分子和配位羟基O原子形成的R₂²(8)型环形氢键桥的连接, 沿a轴方向构建了四核单元交替相连的一维超分子链; 链间籍苯环的π-π堆积作用和晶格水分子氢键链的连接进一步扩展为具有隧道的三维结构. 配合物中呈现了一种2,3-二羟基丁二酸与过渡金属配位的新方式. 变温磁化率研究表明标题配合物具有弱的反铁磁耦合作用.

A Novel Dual-U-shaped Tetranuclear Complex[Cu4(dhbd)2(dpphen)4•2H2O]•8H2O Constructed from 2,3-Dihydroxybutanedioic Acid with New Coordinating Mode

The title complex Cu₄(dhbd)₂(dpphen)₄?2H₂O]?8H₂O(H4dhbd＝2,3-dihydroxybutanedioic acid, dpphen＝4,7-diphenyl-1,10-phenanthroline) has been hydrothermally synthesized and characterized by means of single crystal X-ray diffraction, elemental analysis, IR and TGA analysis. Crystal structural analysis reveals that, because water molecules bond to Cu(II) atoms, the dhbd ligand can only adopt a hydroxyl oxygen atom to bridge two reversed U-shaped subunits into a novel centrosymmetric dual-U-shaped tetranuclear Cu(II) structure. Each U-shaped frame consists of two crystallographically distinct Cu(II) atoms, two dpphen ligands and one coordinated water molecule. Through cyclic hydrogen bonding with motif formed by coordinated water molecules and coordinated hydroxyl groups of dhbd from adjacent tetranuclear units, these adjacent neighbors are connected to afford a 1D supramolecular chain along axis a, which is further extended via aromatic intercalations and other crystallization water molecules into a 3D structure with channels. The binding mode of dhbd group was not observed so far. Variable-temperature magnetic susceptibility measurements indicate the presence of weak antiferromagnetic interactions.