State Key Laboratory of Coordination Chemistry, Coordination Chemistry Institute, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China.
Dalton Trans. 2013 Oct 21;42(39):14075-80. doi: 10.1039/c3dt51742j.
The first examples of metal phosphonates based on 2-phenyl-2-(phosphonomethylamino)acetic acid (ppaH3) are reported, namely, Co3(ppa)2(4,4′-bpy)2(H2O)4·2H2O (1) and Ni4(ppaH)4(4,4′-bpy)2(H2O)2 (2). Compound 1 shows a three-dimensional framework structure in which the Co3(ppa)2 chains are cross-linked by 4,4′-bpy ligands. Within the chain, the equivalent Co2 atoms are doubly bridged by the O–P–O units from the R- and S-ppa(3−) ligands forming a racemic dimer of Co2(ppa)2. The dimers are connected by the Co1 atoms through O–P–O units to form an infinite racemic chain. Compound 2 displays a layer structure, where chains of Ni2(ppaH)2 are fused together by 4,4′-bpy. Within the chain, dimers of equivalent Ni atoms with O–P–O linkages are again observed. Unlike compound 1, however, the opposite handedness dimers are linked via O–C–O bridges into an infinite racemic chain. Magnetic studies reveal that dominant antiferromagnetic interactions are mediated between the magnetic centers in both cases.
首次报道了基于 2-苯-2-（膦酸甲酯基）乙酸（ppaH3）的金属膦酸盐的实例，即 Co3（ppa）2（4,4′-bpy）2（H2O）4·2H2O（1）和 Ni4（ppaH）4（4,4′-bpy）2（H2O）2（2）。化合物 1 呈现出三维框架结构，其中 Co3（ppa）2 链通过 4,4′-bpy 配体交联。在链内，等效的 Co2 原子通过 R-和 S-ppa（3−）配体的 O–P–O 单元双桥接形成 Co2（ppa）2 的外消旋二聚体。二聚体通过 Co1 原子通过 O–P–O 单元连接形成无限的外消旋链。化合物 2 呈现出层状结构，其中 Ni2（ppaH）2 链通过 4,4′-bpy 融合在一起。在链内，再次观察到等效 Ni 原子的二聚体与 O–P–O 键合。然而，与化合物 1 不同，相反手性的二聚体通过 O–C–O 桥连接成无限的外消旋链。磁性研究表明，在这两种情况下，磁中心之间存在主导的反铁磁相互作用。
