Kwak Hyun Young, Ryu Dae Won, Kim Hyoung Chan, Koh Eui Kwan, Cho Beong Ki, Hong Chang Seop
Department of Chemistry, Korea University, Seoul 136-713, Korea.
Dalton Trans. 2009 Mar 21(11):1954-61. doi: 10.1039/b818559j. Epub 2009 Jan 28.
Three cyanide-linked Fe(iii)Mn(iii) bimetallic clusters, (Tp)Fe(CN)(3)Mn(acphen) [; acphen = N,N'-ethylenebis(2-hydroxyacetophenylideneiminato) dianion], (Tp)Fe(CN)(3)Mn(5-Bracphen) [; 5-Bracphen = N,N'-ethylenebis(5-bromo-2-hydroxyacetophenylideneiminato) dianion], and (Tp)Fe(CN)(3)Mn(salen).6H(2)O [; salen = N,N'-ethylenebis(salicylidineiminato) dianion], were prepared by self-assembling a facial (Tp)Fe(CN)(3) [Tp = hydrotris(pyrazolyl)borate] precursor and respective Mn(iii) Schiff bases. X-Ray crystal structure analyses revealed that each complex is composed of a central Mn(iii) dimer doubly linked by phenoxides of the tetradentate N(2)O(2) Schiff bases and the terminal (Tp)Fe(CN)(3) groups connecting to the center through cyanides. Using the spin Hamiltonian H = -2J(1)(S(Fe1).S(Mn1) + S(Mn1a).S(Fe1a)) - 2J(2)(S(Mn1).S(Mn1a)), where J(1) stands for the exchange coupling constant between Fe(iii) (S(Fe) = 1/2) and Mn(iii) (S(Mn) = 2) through cyanides and J(2) between Mn(iii) ions via phenoxides, the best fits corresponded to J(1) = 2.61 cm(-1) and J(2) = 0.85 cm(-1) for , J(1) = 2.50 cm(-1) and J(2) = 1.30 cm(-1) for , and J(1) = -2.15 cm(-1) and J(2) = 0.55 cm(-1) for . The phenoxide routes transmit ferromagnetic interactions in all cases, while ferromagnetic or antiferromagnetic couplings occur through the cyanide linkage. Although the geometric parameters relevant to the magnetic Fe-C[triple bond, length as m-dash]N-Mn pathways are analogous to each other their magnetic natures are varied across the compounds, which supports that a degree of orbital overlap is quite sensitive to a subtle structural change in the present system.
通过自组装面式[(Tp)Fe(CN)(3)]- [Tp = 氢三(吡唑基)硼酸根]前体和相应的Mn(III)席夫碱，制备了三种氰基连接的Fe(III)Mn(III)双金属簇合物，[(Tp)Fe(CN)(3)]2[Mn(acphen)]2 [；acphen = N,N'-亚乙基双(2-羟基乙酰苯亚氨基)二价阴离子]，[(Tp)Fe(CN)(3)]2[Mn(5-Bracphen)]2 [；5-Bracphen = N,N'-亚乙基双(5-溴-2-羟基乙酰苯亚氨基)二价阴离子]，以及[(Tp)Fe(CN)(3)]2[Mn(salen)]2·6H2O [；salen = N,N'-亚乙基双(水杨醛亚氨基)二价阴离子]。X射线晶体结构分析表明，每个配合物均由一个中心Mn(III)二聚体组成，该二聚体通过四齿N2O2席夫碱的酚氧基双重连接，末端[(Tp)Fe(CN)(3)]-基团通过氰基连接到中心。使用自旋哈密顿量H = -2J1(S(Fe1)·S(Mn1) + S(Mn1a)·S(Fe1a)) - 2J2(S(Mn1)·S(Mn1a))，其中J1代表通过氰基的Fe(III)（S(Fe) = 1/2）和Mn(III)（S(Mn) = 2）之间的交换耦合常数，J2代表通过酚氧基的Mn(III)离子之间的交换耦合常数，对于 ，最佳拟合对应J1 = 2.61 cm-1和J2 = 0.85 cm-1，对于 ，J1 = 2.50 cm-1和J2 = 1.30 cm-1，对于 ，J1 = -2.15 cm-1和J2 = 0.55 cm-1。在所有情况下，酚氧基路径传递铁磁相互作用，而通过氰基连接发生铁磁或反铁磁耦合。尽管与磁性Fe-C≡N-Mn路径相关的几何参数彼此相似，但它们在各化合物中的磁性性质不同，这支持了轨道重叠程度对本体系中细微结构变化相当敏感。
