State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, The Chinese Academy of Sciences, Fuzhou, Fujian 350002, China.
Dalton Trans. 2010 Aug 21;39(31):7276-85. doi: 10.1039/c002474k. Epub 2010 Jun 28.
The use of phosphonic acids in the synthesis of mixed-metal CeMn complexes has led to the formation of two phosphonate complexes with unusual topologies: [Ce(2)Mn(6)O(6)(OH)(5)(t-BuPO(3))(6)(O(2)CMe)(3)] x 53 H(2)O (1 x 53 H(2)O) and Ce(22)Mn(12)O(34)(MePO(3))(12)(O(2)CMe)(33)(OMe)(6)(NO(3))(H(2)O)(12) (2). The two mixed-metal CeMn complexes were both prepared from a reaction system containing Mn(O(2)CMe)(2) and (NH(4))(2)[Ce(NO(3))(6)] with similar procedures except for using different phosphonic acids (tert-butylphosphonic acid and methylphosphonic acid, respectively) as coligands. Both complexes possess rare topology of triangular type, with compound 1 being a 0D discrete cluster, whereas, compound 2 is a 1D polymer. The octanuclear core of complex 1 is composed of three symmetry equivalent distorted cubanes {Ce(IV)(2)Mn(IV)(2)O(2)(OH)(2)} sharing a trigonal-bipyramidal unit {Ce(IV)(2)(OH)(3)} in the centre. Compound 2 is a one-dimensional chain polymer of identical Ce(22)Mn(12)O(34) units linked together by NO(3)(-) and MeCO(2)(-) groups, while the Ce(22)Mn(12)O(34) unit is constituted by two centrosymmetric Ce(9)(IV)Ce(2)(III)Mn(IV)(6)O(17) subunits, which features three identical distorted cubanes {Ce(IV)(2)Mn(IV)(2)O(4)} connecting to a central trigonal-bipyramidal unit {Ce(IV)(3)O(2)}, and two additional Ce(III) ions capping the top and bottom of the central trigonal bipyramid by six MePO(3)(2-) ligands. Complexes 1 and 2 are the first high-nuclearity Mn/Ln aggregates reported to date using phosphonates as ligands. Magnetic susceptibility measurements reveal that compound 1 displays dominant ferromagnetic interactions between the adjacent metal ions with the best fit parameters for the exchanges are J(1) = 6.186 cm(-1), J(2) = 4.172 cm(-1), and with a result of S = 9 ground state confirmed by the M versus HT(-1) data, which indicates the spins of all the six Mn(IV) ions in the cluster are parallel to each other. In contrast, the data for 2 reveals overall antiferromagnetic couplings within the cluster and a resulting S = 6 ground state. Both the in-phase signal chi'(M)T and out-of-phase signal chi''(M) of the two complexes exhibit frequency-dependent below approximate 3 K.
在混合金属 CeMn 配合物的合成中使用膦酸导致了两种具有不同拓扑结构的膦酸盐配合物的形成：[Ce(2)Mn(6)O(6)(OH)(5)(t-BuPO(3))(6)(O(2)CMe)(3)] x 53 H(2)O (1 x 53 H(2)O) 和 Ce(22)Mn(12)O(34)(MePO(3))(12)(O(2)CMe)(33)(OMe)(6)(NO(3))(H(2)O)(12) (2)。这两种混合金属 CeMn 配合物均由反应体系制备，其中 Mn(O(2)CMe)(2)和 (NH(4))(2)[Ce(NO(3))(6)]与类似的程序一起使用，但使用了不同的膦酸（叔丁基膦酸和甲基膦酸，分别）作为共配体。这两种配合物都具有罕见的三角形拓扑结构，化合物 1 是一个 0D 离散簇，而化合物 2 是一个 1D 聚合物。化合物 1 的八核核心由三个对称等效的变形立方烷{Ce(IV)(2)Mn(IV)(2)O(2)(OH)(2)}组成，中心共享一个三角双锥单元{Ce(IV)(2)(OH)(3)}。化合物 2 是由相同的 Ce(22)Mn(12)O(34)单元通过 NO(3)(-)和 MeCO(2)(-)基团连接而成的一维链聚合物，而 Ce(22)Mn(12)O(34)单元由两个中心对称的 Ce(9)(IV)Ce(2)(III)Mn(IV)(6)O(17)亚基组成，其特征是三个相同的变形立方烷{Ce(IV)(2)Mn(IV)(2)O(4)}连接到一个中心三角双锥单元{Ce(IV)(3)O(2)}，以及两个额外的 Ce(III)离子通过六个 MePO(3)(2-)配体覆盖中央三角双锥的顶部和底部。复合物 1 和 2 是迄今为止使用膦酸作为配体报道的第一批高核 Mn/Ln 聚集体。磁导率测量表明，化合物 1 显示相邻金属离子之间的主导铁磁相互作用，最佳交换参数为 J(1) = 6.186 cm(-1)，J(2) = 4.172 cm(-1)，并且通过 M 对 HT(-1)数据确定的结果为 S = 9 基态，这表明簇中所有六个 Mn(IV)离子的自旋彼此平行。相比之下，2 的数据表明簇内存在整体反铁磁耦合，导致 S = 6 基态。两种配合物的同相信号 chi'(M)T 和反相信号 chi''(M)都在大约 3 K 以下表现出频率依赖性。
