Arora Himanshu, Lloret Francesc, Mukherjee Rabindranath
Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, India.
Inorg Chem. 2009 Feb 2;48(3):1158-67. doi: 10.1021/ic800861m.
Structural characterization of the newly synthesized complexes [M(I)I(L(1)OO)(xH2O)][ClO4] x 2 H2O [M = Co, x = 1 (1); M = Cu, x = 0 (2); L(1)OO- = 3-[(2-(pyridin-2-yl)ethyl){2-(pyridin-2-yl)methyl}amino]propionate] reveals that 1 and 2 are 1D chainlike coordination polymers. A tridentate variety of this ligand afforded a discrete tetranuclear complex {[Cu(I)I(L(2)OO)(OClO3)]}4 x MeCN (3) [L(2)OO- = 3-[N-methyl-{2-(pyridine-2-yl)ethyl}amino]propionate]. Analysis of the crystal packing diagrams reveals extensive pi-pi stacking in 1 and C-H...O hydrogen bonding interactions in 3, leading to the formation of network structures. For these complexes, absorption spectral properties have been investigated. All three complexes exhibit exchange interaction between the M(II) ions through a syn-anti bridging carboxylate pathway. Magnetic studies on 1 show spontaneous magnetization below 5 K, which corresponds to the presence of spin-canted antiferromagnetism. At T = 2 K, the values of coercive field (H(c)) and remnant magnetization (M(r)) are 200 G and 0.019 muB, respectively. Analysis of the magnetic data through spin Hamiltonians in the form HH = sigma(i<j)(n) -J(ij)S(i)S(j) (J is positive for a ferromagnetic interaction and negative for an antiferromagnetic interaction) leads to the following set of best-fit parameters: J = -2.65(2), -0.66(1), and +12.2(2) cm(-1) for 1, 2, and 3, respectively. An attempt has been made to rationalize the observed magnetic behavior.
新合成的配合物[M(I)I(L(1)OO)(xH₂O)][ClO₄]·2H₂O[M = Co，x = 1 (1)；M = Cu，x = 0 (2)；L(1)OO⁻ = 3 - [(2 - (吡啶 - 2 - 基)乙基){2 - (吡啶 - 2 - 基)甲基}氨基]丙酸酯]的结构表征表明，1和2是一维链状配位聚合物。该配体的一种三齿变体得到了离散的四核配合物{[Cu(I)I(L(2)OO)(OClO₃)]}₄·MeCN (3)[L(2)OO⁻ = 3 - [N - 甲基 - {2 - (吡啶 - 2 - 基)乙基}氨基]丙酸酯]。对晶体堆积图的分析表明，1中存在广泛的π - π堆积，3中存在C - H...O氢键相互作用，导致形成网络结构。对这些配合物的吸收光谱性质进行了研究。所有三种配合物都通过顺 - 反桥连羧酸根途径在M(II)离子之间表现出交换相互作用。对1的磁性研究表明，在5 K以下存在自发磁化，这对应于自旋倾斜反铁磁性的存在。在T = 2 K时，矫顽场(H(c))和剩余磁化强度(M(r))的值分别为200 G和0.019 μB。通过形式为HH = ∑(i<j)(n) -J(ij)S(i)S(j)(J对于铁磁相互作用为正，对于反铁磁相互作用为负)的自旋哈密顿量对磁性数据进行分析，得到以下一组最佳拟合参数：对于1、2和3，J分别为 - 2.65(2)、 - 0.66(1)和 + 12.2(2) cm⁻¹。已尝试对观察到的磁性行为进行合理化解释。
