A unique single carboxylate-bridged spin-frustrated chiral Mn(II) metallatriangle.
A unique single carboxylate-bridged spin-frustrated chiral Mn(II) metallatriangle.
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DOI：
10.1039/c0dt00613k
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发表时间：
2010-10
影响因子：
4
通讯作者：
Jesus E. Perea-Buceta;A. Mota;J. Costes;R. Sillanpää;J. Krzystek;E. Colacio
中科院分区：
文献类型：
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作者：
Jesus E. Perea-Buceta;A. Mota;J. Costes;R. Sillanpää;J. Krzystek;E. Colacio
5-甲基-4-氰基-双嘧啶经NaOH水解制得的Hmbpymca配体与1：1摩尔比的Mn(ClO(4))(2)·4H(2)O按1：1的摩尔比反应得到了三角三锰(II)配合物[Mn(3)(Bpymca)(3)(H(2)O)(6)]Cl(3)·6H(2)O 1。1的分子结构由具有C(3)对称性的阳离子分子三角形[Mn(3)(μ-mbpymca)(3)(H(2)O)(6)](3+)、氯离子和结晶水分子组成，它们都参与了一个广泛的氢键网络，形成了一个手性网络。在[Mn(3)(μ-mbpymca)(3)(H(2O)O)(6)](3+)阳离子中，七配位的Mn(II)离子被羧酸根的两个氧原子桥联，表现出MnO(5)N(2)压缩的五方双锥配位环境。磁化率的温度依赖关系表明，在4K以下，由MBpymca配体的羧酸基介导的Mn(II)离子之间存在弱的反铁磁相互作用，并且存在三维反铁磁有序。7K以上的实验磁化率数据与自旋哈密顿量H=-J(S(1)S(2)+S(1)S(3)+S(2)S(3))的理论解析表达式符合得很好，其中J=-0.782(3)cm(-1)，g=2.092(3)。该模型预测了S=1/2的简并基态，这是含有非整数自旋金属的三角形三金属自旋受阻系统的典型特征。对固体中的分子结构进行了密度泛函理论计算，以支持实验的J值和以Mn-O(Carb)-Mn为主要交换途径。
The reaction between Hmbpymca ligand (prepared in situ from the hydrolysis of 5-methyl-4-cyano-bispyrimidine with NaOH and further neutralization with 2 M HCl) and Mn(ClO(4))(2)·4H(2)O in 1:1 molar ratio afforded the triangulo-trimanganese(II) complex [Mn(3)(bpymca)(3)(H(2)O)(6)]Cl(3)·6H(2)O 1. The chloride anions in this complex come from the HCl used in the neutralization process. The molecular structure of 1 consists of cationic molecular triangles [Mn(3)(μ-mbpymca)(3)(H(2)O)(6)](3+) with C(3) symmetry, chloride anions and crystallization water molecules, all of them involved in an extensive network of hydrogen bonds, leading to a chiral network. Within the [Mn(3)(μ-mbpymca)(3)(H(2)O)(6)](3+) cations, seven-coordinated Mn(II) ions are bridged by both oxygen atoms of the carboxylate groups and exhibit a MnO(5)N(2) compressed pentagonal bipyramidal coordination environment. The temperature dependence of the magnetic susceptibility shows the presence of weak antiferromagnetic interactions between Mn(II) ions mediated by the carboxylate group of the mbpymca ligand and the existence of a 3D antiferromagnetic ordering below 4 K, which has its origin in the AF inter-trimer exchange interactions mediated by the strong hydrogen bonds present in the crystal of 1. The experimental magnetic susceptibility data above 7 K could be satisfactorily fitted to the theoretical analytical expression derived from the spin Hamiltonian H = -J(S(1)S(2) + S(1)S(3) + S(2)S(3)) with J = -0.782(3) cm(-1) and g = 2.092(3). The model predicts a degenerate ground state with an S = 1/2, which is typical of triangular trimetallic spin frustrated systems containing metal with non-integer spins. DFT calculations were performed on the molecular structure as found in the solid state to support the experimental J value and the Mn-O(carb)-Mn as the primarily exchange pathway.