Departament de Química Inorganìca/Instituto de Ciencia Molecular, Facultat de Química de la Universitat de València, Catedrático José Beltrán Martinez, n°2, 46980 Paterna, Valencia, Spain.
Dalton Trans. 2012 Nov 28;41(44):13716-26. doi: 10.1039/c2dt31675g. Epub 2012 Oct 2.
We herein present the synthesis and magneto-structural study of a new family of heterobimetallic chains of general formula {Fe(III)(dmbpy)(CN)(4)M(II)(H(2)O)(2)}(n)·pnH(2)O [dmbpy = 4,4'-dimethyl-2,2'-bipyridine; M = Mn (2), Cu (3), Ni (4) and Co (5) with p = 4 (2), 3 (3), 9 (4) and 3.5 (5)] which were prepared by using the mononuclear PPh(4)[Fe(III)(dmbpy)(CN)(4)]·3H(2)O (1) building block (PPh(4)(+) = tetraphenylphosphonium) as a ligand toward fully solvated M(II) ions. The structure of 1 consists of discrete Fe(III)(dmbpy)(CN)(4) anions, tetraphenylphosphonium cations and noncoordinated water molecules. Complexes 2-5 are isostructural compounds whose structure consists of neutral 4,2-wave like heterobimetallic chains of formula {Fe(III)(dmbpy)(CN)(4)M(II)(H(2)O)(2)}(n) where the Fe(III)(dmbpy)(CN)(4) entity adopts a bis-monodentate coordination mode toward trans-[M(II)(H(2)O)(2)] units through two of its four cyanide groups in cis positions. 1 exhibits the magnetic behaviour of magnetically isolated six-coordinate low-spin Fe(III) complexes with an important orbital contribution. 2 behaves as ferrimagnetic Fe(III)(2)Mn(II) chains, whereas 3-5 exhibit intrachain ferromagnetic couplings between the low-spin Fe(III) and either Cu(II) (3), Ni (4) or Co(II) (5) as well as frequency-dependence of the out-of-phase ac susceptibility signals below 3.0 (3), 5.5 (4) and 5.0 K (5). The relaxation time and the energy to reverse the magnetization of 3-5 are related to the anisotropy of the M(II) center and to the intra- and interchain magnetic interactions. Unprecedentedly in the world of cyanide-bearing complexes, 5 exhibits a double slow relaxation of the magnetization.
我们在此介绍了一类新的异双核链的合成和磁结构研究，其通式为{Fe(III)(dmbpy)(CN)4M(II)(H2O)2}(n)·pnH2O [dmbpy = 4,4'-二甲基-2,2'-联吡啶；M = Mn(2), Cu(3), Ni(4)和 Co(5)，其中 p = 4(2), 3(3), 9(4)和 3.5(5)]，这些化合物是通过使用单核 PPh4[Fe(III)(dmbpy)(CN)4]·3H2O (1)作为配体来制备的，其中 PPh4(+) = 四苯膦。1 的结构由离散的Fe(III)(dmbpy)(CN)4阴离子、四苯膦阳离子和非配位水分子组成。配合物 2-5 是等结构的化合物，其结构由中性 4,2-波状异双核链组成，通式为{Fe(III)(dmbpy)(CN)4M(II)(H2O)2}(n)，其中Fe(III)(dmbpy)(CN)4实体通过其四个氰化物基团中的两个处于顺式位置，以双单齿配位模式与顺式-[M(II)(H2O)2]单元配位。1 表现出六配位低自旋 Fe(III)配合物的磁行为，具有重要的轨道贡献。2 表现为铁磁 Fe(III)(2)Mn(II)链，而 3-5 表现出低自旋 Fe(III)与 Cu(II)(3)、Ni(4)或 Co(II)(5)之间的链内铁磁耦合，以及在 3.0(3)、5.5(4)和 5.0 K(5)以下的交流磁化率信号的频率依赖性。3-5 的弛豫时间和反转磁化的能量与 M(II)中心的各向异性和链内和链间磁相互作用有关。在含氰化物配合物的世界中，5 表现出前所未有的磁弛豫的双重缓慢。
