Synthesis and characterization of a new family of bi-, tri-, tetra-, and pentanuclear ferric complexes.
Synthesis and characterization of a new family of bi-, tri-, tetra-, and pentanuclear ferric complexes.
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DOI：
10.1021/ic049600f
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发表时间：
2004-07
影响因子：
4.6
通讯作者：
C. Boskovic;A. Sieber;G. Chaboussant;H. Güdel;J. Ensling;W. Wernsdorfer;A. Neels;G. Labat;H. S
中科院分区：
文献类型：
--
作者：
C. Boskovic;A. Sieber;G. Chaboussant;H. Güdel;J. Ensling;W. Wernsdorfer;A. Neels;G. Labat;H. S
合成了一个新的多核铁配合物家族的九个成员，并对其进行了表征。Fe（O（2）CMe）（2）与水杨醛缩2-乙醇胺衍生的多齿Schiff碱前配体（H（2）L）反应，在某些情况下与羧酸反应，得到通式为[Fe（2）（pic）（2）（L）（2）]的新配合物（其中pic（-）是2-吡啶甲酸的阴离子）、[Fe（3）（O（2）CMe）（3）（L）（3）]、[Fe（4）（OR）（2）（O（2）CMe）（2）（L）（4）]和[Fe（5）O（OH）（O（2）CR）（4）（L）（4）]。三核、四核和五核配合物都具有独特的结构和新颖的拓扑结构。穆斯堡尔谱证实了三核和五核配合物中存在高自旋铁中心。变温磁测量表明自旋基态S = 0，1/2，0，和5/2的双，三，四，和五核配合物，分别。拟合的磁化率数据提供了专门的反铁磁交换相互作用的大小。此外，已经观察到五核配合物的易轴型磁各向异性，通过模拟低温磁化数据确定的D值约为-0.4 cm（-）（1）。一个五核配合物的低温微SQUID研究揭示了在非零场的磁化滞后。这是由于各向异性诱导的能量势垒的磁化反转是分子起源。最后，一个三核配合物的非弹性中子散射研究表明，磁行为来自两个不同的物种。
Nine members of a new family of polynuclear ferric complexes have been synthesized and characterized. The reaction of Fe(O(2)CMe)(2) with polydentate Schiff base proligands (H(2)L) derived from salicylidene-2-ethanolamine, followed in some cases by reaction with carboxylic acids, has afforded new complexes of general formulas [Fe(2)(pic)(2)(L)(2)] (where pic(-) is the anion of 2-picolinic acid), [Fe(3)(O(2)CMe)(3)(L)(3)], [Fe(4)(OR)(2)(O(2)CMe)(2)(L)(4)], and [Fe(5)O(OH)(O(2)CR)(4)(L)(4)]. The tri-, tetra-, and pentanuclear complexes all possess unusual structures and novel core topologies. Mössbauer spectroscopy confirms the presence of high-spin ferric centers in the tri- and pentanuclear complexes. Variable-temperature magnetic measurements suggest spin ground states of S = 0, 1/2, 0, and 5/2 for the bi-, tri-, tetra-, and pentanuclear complexes, respectively. Fits of the magnetic susceptibility data have provided the magnitude of the exclusively antiferromagnetic exchange interactions. In addition, an easy-axis-type magnetic anisotropy has been observed for the pentanuclear complexes, with D values of approximately -0.4 cm(-)(1) determined from modeling the low-temperature magnetization data. A low-temperature micro-SQUID study of one of the pentanuclear complexes reveals magnetization hysteresis at nonzero field. This is attributed to an anisotropy-induced energy barrier to magnetization reversal that is of molecular origin. Finally, an inelastic neutron scattering study of one of the trinuclear complexes has revealed that the magnetic behavior arises from two distinct species.