Departamento de Química Inorgánica, Facultad de Física Universidad de La Laguna, 38206 La Laguna (Tenerife), Spain.
Inorg Chem. 2010 Sep 6;49(17):7880-9. doi: 10.1021/ic100786j.
Two new compounds K(3)[Cu(3)(Hmesox)(3)(H(2)O)] x 4 H(2)O (1) and {(PPh(4))(2)[CoCu(3)(Hmesox)(3)Cl]} (2) [H(4)mesox = mesoxalic acid (2-dihydroxymalonic acid) and PPh(4)(+) = tetraphenylphosphonium cation] have been prepared and magneto-structurally characterized. Compound 1 contains the Cu(3)(Hmesox)(3) entity which can be considered as a new precursor for molecular magnetism. In 1 the triangular arrangement of three copper(II) ions bridged by alkoxo groups are further connected to a symmetry-related tricopper(II) unit through a double oxo(carboxylate) bridge. The resulting hexacopper(II) entities are joined further through anti-syn carboxylate groups into an anionic three-dimensional network of formula Cu(3)(Hmesox)(3)(H(2)O)(3n-) whose charge is neutralized by univalent potassium cations. The strong decrease of the chi(M)T product [per three copper(II) ions] in the high temperature range with the occurrence of a plateau for a spin doublet at T < 65 K is as expected for the coexistence of two antiferromagnetic interactions within the quasi isosceles tricopper(II) core of 1 [J = -194(1) cm(-1) and j = -3(4) cm(-1), the Hamiltonian being defined as H = -J(S(1) x S(2) + S(2) x S(3)) - j(S(1) x S(2))]. Compound 2 exhibits a chiral three-dimensional structure which is made up of an anionic Co(II)Cu(II)(3)(mu(3)-Cl)(Hmesox)(3)(2n-) framework with a (10,3)-a topology whose cavities are filled by PPh(4)(+) cations. The Cu(II)(3)(mu(3)-Cl)(Hmesox)(3) tricopper(II) unit in 2 acts as a tris-bidentate ligand through the Hmesox groups toward three cobalt(II) ions, these latter ones being tris-chelated. Alternating current (ac) and direct current (dc) magnetic susceptibility measurements of 2 show a ferrimagnetic behavior with a magnetic ordering at T(c) = 18.5 K and a coercive field H(c) = 5000 G. As shown by the magneto-structural study of 2, the use as a ligand of 1 versus metal ions other than cobalt(II) or preformed complexes whose coordination sphere is partially blocked represents a new and rational preparative route toward multifunctional heterometallic compounds.
两种新的化合物 K(3)[Cu(3)(Hmesox)(3)(H(2)O)] x 4 H(2)O (1) 和 {(PPh(4))(2)[CoCu(3)(Hmesox)(3)Cl]} (2) [H(4)mesox = 马来酸二甲酯（2-二羟基亚戊二酸）和 PPh(4)(+) = 四苯膦阳离子] 已经被制备和磁性结构表征。化合物 1 包含 Cu(3)(Hmesox)(3) 实体，可被视为分子磁体的新前体。在 1 中，三个铜（II）离子通过烷氧基桥接的三角形排列通过双氧（羧酸酯）桥进一步连接到对称相关的三铜（II）单元。所得的六铜（II）实体通过反顺羧酸酯基团进一步连接成一个阴离子三维网络，其化学式为 Cu(3)(Hmesox)(3)(H(2)O)(3n-)，其电荷由单价钾阳离子中和。在高温范围内，chi(M)T 产物 [每个三个铜（II）离子] 的强烈下降伴随着自旋双峰在 T < 65 K 时的平台的出现，这是由于 1 中准等腰三铜（II）核内存在两种反铁磁相互作用的共存所致 [J = -194(1) cm(-1) 和 j = -3(4) cm(-1)，哈密顿量定义为 H = -J(S(1) x S(2) + S(2) x S(3)) - j(S(1) x S(2))]。化合物 2 表现出手性三维结构，由阴离子 Co(II)Cu(II)(3)(mu(3)-Cl)(Hmesox)(3)(2n-) 骨架组成，其拓扑结构为 (10,3)-a，其空腔被 PPh(4)(+) 阳离子填充。2 中的 Cu(II)(3)(mu(3)-Cl)(Hmesox)(3) 三铜（II）单元通过 Hmesox 基团充当三配位配体，向三个钴（II）离子配位，这些钴（II）离子是三螯合的。2 的交流（ac）和直流（dc）磁化率测量显示出铁磁行为，在 T(c) = 18.5 K 时具有磁序，矫顽场 H(c) = 5000 G。正如 2 的磁结构研究所示，将 1 用作配体而不是钴（II）或配位球部分受阻的预形成配合物的金属离子的使用代表了一种新的、合理的制备多功能杂金属化合物的方法。
