Department of Chemistry (BK21), Korea University, Seoul 136-713, Korea.
Inorg Chem. 2010 May 17;49(10):4632-42. doi: 10.1021/ic100301q.
Reaction of (Tp)Fe(CN)(3) [Tp = hydrotris(pyrazolyl)borate] with respective Mn(III) Schiff bases led to the formation of four dimeric molecules, [(Tp)Fe(CN)(3)][Mn(1-napen)(H(2)O)].MeCN.4H(2)O [1; 1-napen = N,N'-ethylenebis(2-hydroxy-1-naphthylideneiminato) dianion], [(Tp)Fe(CN)(3)][Mn(5-Clsalen)(H(2)O)] [2; 5-Clsalcy = N,N'-(trans-1,2-cyclohexanediylethylene)bis(5-chlorosalicylideneiminato) dianion], [(Tp)Fe(CN)(3)][Mn(2-acnapen)(MeOH)].MeOH [3; 2-acnapen = N,N'-ethylenebis(1-hydroxy-2-acetonaphthylideneiminato) dianion], [(Tp)Fe(CN)(3)][Mn(3-MeOsalen)(H(2)O)] [4; 3-MeOsalen = N,N'-ethylenebis(3-methoxysalicylideneiminato) dianion], and a one-dimensional (1D) zigzag chain [(Tp)Fe(CN)(3)][Mn(2-acnapen)].H(2)O (5). The dimers contain multiple intermolecular interactions such as hydrogen bonds, face-to-face pi-pi contacts, and edge-to-face CH-pi forces, raising molecular dimensions from one-dimensional (1D) up to three-dimensional (3D) arrays, whereas there are no pi-pi stacking interactions in the 1D chain compound. Magnetic measurements reveal that ferromagnetic couplings are obviously operative between Mn(III) and Fe(III) spin centers transmitted by CN bridges for 1-3 and 5, and antiferromagnetic interactions are however unexpectedly present in 4. On the basis of the proper spin Hamiltonians, magnetic exchange couplings are estimated to be in the span from 1.79 to 7.48 cm(-1) for the ferromagnetically coupled systems and -1.40 cm (-1) for the antiferromagnetic dimer. A slow magnetic relaxation is tangible in 5, which is in connection with isolated chains devoid of any intermolecular noncovalent interactions. Density Functional Theory (DFT) calculations and comparison of structural parameters suggest that the observed magnetic behaviors are mainly associated with the bending of the Mn-N[triple bond]C angle in the bridging pathway.
[(Tp)Fe(CN)(3)]- [Tp = 氢化三(吡唑基)硼]与相应的 Mn(III)Schiff 碱反应生成了四个二聚体分子，[(Tp)Fe(CN)(3)][Mn(1-napen)(H(2)O)].MeCN.4H(2)O [1; 1-napen = N,N'-亚乙基双(2-羟基-1-萘基亚氨基)二阴离子]，[(Tp)Fe(CN)(3)][Mn(5-Clsalen)(H(2)O)] [2; 5-Clsalcy = N,N'-(反式-1,2-环己烷二亚乙基)双(5-氯水杨醛亚氨基)二阴离子]，[(Tp)Fe(CN)(3)][Mn(2-acnapen)(MeOH)].MeOH [3; 2-acnapen = N,N'-亚乙基双(1-羟基-2-乙酰萘亚氨基)二阴离子]，[(Tp)Fe(CN)(3)][Mn(3-MeOsalen)(H(2)O)] [4; 3-MeOsalen = N,N'-亚乙基双(3-甲氧基水杨醛亚氨基)二阴离子]和一维 (1D) 锯齿链 [(Tp)Fe(CN)(3)][Mn(2-acnapen)].H(2)O (5)。这些二聚体包含多种分子间相互作用，如氢键、面对面的 pi-pi 接触和边缘对 pi 的力，从而将分子尺寸从一维 (1D) 提升到三维 (3D) 排列，而在一维链状化合物中不存在 pi-pi 堆积相互作用。磁性测量表明，在 1-3 和 5 中，CN 桥通过 Mn(III)和 Fe(III)自旋中心之间的明显铁磁耦合传输，而在 4 中则存在反铁磁相互作用。基于适当的自旋哈密顿量，估计铁磁耦合体系的磁交换耦合在 1.79 到 7.48 cm(-1)之间，而反铁磁二聚体的磁交换耦合为-1.40 cm(-1)。在 5 中可以明显感受到缓慢的磁弛豫，这与缺乏任何分子间非共价相互作用的孤立链有关。密度泛函理论 (DFT) 计算和结构参数比较表明，观察到的磁行为主要与桥接途径中 Mn-N[三重键]C 角的弯曲有关。
