Synthesis, crystal structure and magnetic behavior of three polynuclear complexes: [Co(pyo)2(dca)2]n, [Co3(ac)4(bpe)3(dca)2]n and [{Co(male)(H2O)2}(H2O)]n [pyo, pyridine-N-oxide; dca, dicyanamide; ac, acetate; bpe, 1,2-bis-(4-pyridyl)ethane and male, male
Synthesis, crystal structure and magnetic behavior of three polynuclear complexes: [Co(pyo)2(dca)2]n, [Co3(ac)4(bpe)3(dca)2]n and [{Co(male)(H2O)2}(H2O)]n [pyo, pyridine-N-oxide; dca, dicyanamide; ac, acetate; bpe, 1,2-bis-(4-pyridyl)ethane and male, male
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DOI：
10.1039/b401928h
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发表时间：
2004-10
影响因子：
3.3
通讯作者：
D. Ghoshal;G. Mostafa;T. Maji;E. Zangrando;T. Lu;J. Ribas;N. R. Chaudhuri
中科院分区：
文献类型：
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作者：
D. Ghoshal;G. Mostafa;T. Maji;E. Zangrando;T. Lu;J. Ribas;N. R. Chaudhuri
[Co(pyo)2(dca)2]n(1)、[Co3(ac)4(bpe)3 (dca)2]n(2)和[{Co（公）（H2O）2(H2O)]n (3)] [pyo，吡啶- n -氧化物]的三种聚合钴（II）配合物dca, dicyanamide;交流,乙酸;合成了Bpe， 1,2-二-（4-吡啶基）乙烷和雄性，雄性酸盐]，并对其进行了结构和磁性表征。对配合物1的结构测定表明，其一维配位链上的每个八面体Co（II）分别附着4个μ-1,5-二氰酰胺和2个悬垂的吡啶- n-氧化物配体，通过非共价π-π相互作用与其他一维链形成相互关系，形成二维无限片状结构。分子结构表明，配合物2采用无限三腿梯形结构，其中三个平行的1D Co（bpe）链通过syn-syn和氧桥接乙酸配体连接。二氰酰胺配体与末端的Co（II）中心相连。配合物3是一个无限的三维网络，其中羧酸基团的马来酸配体以顺反方式连接到Co（II）中心。络合物3的结构已经被报道过。对这三种配合物进行了变温（300-2 K）磁测量。在2的情况下，整个结构可以合理化为准孤立三聚体；描述低温下有效S′= 1/2自旋之间磁相互作用的交换哈密顿量为。根据4 K处的EPR测量值，固定g⊥= 6.01和g∣∣= 2.25,2J =−3.3 cm−1是最佳拟合参数。对于1和3，分别计算一维和三维结构对应的J参数是不可能完全拟合的。对于1只计算了一个近似的J值。
Three polymeric cobalt(II) complexes of formulae [Co(pyo)2(dca)2]n (1), [Co3(ac)4(bpe)3 (dca)2]n (2) and [{Co(male)(H2O)2(H2O)]n (3) [pyo, pyridine-N-oxide; dca, dicyanamide; ac, acetate; bpe, 1,2-bis-(4-pyridyl)ethane and male, maleate] have been synthesized and characterized structurally as well as magnetically. The structure determination of complex 1 shows that each octahedral Co(II) in the 1D coordination chain is attached with four μ-1,5-dicyanamide and two pendant pyridine-N-oxide ligands, which form mutual relationships with other 1D chains through non-covalent π-π interactions, giving rise to a 2D infinite sheet-like structure. The molecular structure reveals that complex 2 adopts an infinite three-leg ladder-like structure in which three parallel 1D Co(bpe) chains are connected by syn-syn and oxo bridging acetate ligands. The dicyanamide ligands are pendant to the terminal Co(II) centers. Complex 3 is an infinite 3D network in which carboxylate groups of the maleate ligand are linked to Co(II) centers in syn-anti fashion. The structure of complex 3 has already been reported. The variable temperature (300–2 K) magnetic measurements have been performed for all three complexes. In the case of 2, the full structure can be rationalized as quasi-isolated trimers; the exchange Hamiltonian that describes magnetic interactions between the effective S′ = 1/2 spins, at low temperature is . Fixing g⊥ = 6.01 and g∣∣ = 2.25, according to the EPR measurements at 4 K, 2J = −3.3 cm−1 is the best-fit parameter. For 1 and 3, complete fits are not possible for calculating the corresponding J parameters for the one- and three-dimensional structures, respectively. Only an approximate J value has been calculated for 1.