手性自旋转换铁(Ⅱ)席夫碱配合物的合成、结构及其磁性研究  

Syntheses, Structures and Magnetic Properties of Homochiral Spin-Crossover Iron(Ⅱ) Schiff-Base Complexes

作　　者：任冬红 刘志明 孙晓利 顾玲 邱丹 顾志国[1,2] 李在均 

机构地区：[1]江南大学化学与材料工程学院,无锡214122 [2]食品胶体与生物技术教育部重点实验室,无锡214122

出　　处：《无机化学学报》2015年第3期536-542,共7页Chinese Journal of Inorganic Chemistry

基　　金：国家自然科学基金(No.21101078;21276105);新世纪优秀人才计划(No.NCET-11-0657);江苏省自然科学基金(No.BK2011143)资助

摘　　要：通过高氯酸亚铁,4-(咪唑-2-甲醛)丁腈和光学纯苯乙胺衍生物的自组装成功合成了2个纯手性单核自旋转换铁(Ⅱ)化合物fac-Λ-[Fe(R-L1)3](Cl O4)2(1),fac-Λ-[Fe(R-L2)3](Cl O4)2(2)。利用X-射线单晶衍射、元素分析(EA)、红外光谱(IR)、核磁共振氢谱(1H NMR)、紫外光谱(UV)、圆二光谱(CD)等手段对配合物结构进行了表征。X-射线单晶衍射表明在化合物1和2中,铁(Ⅱ)金属中心与3个不对称双齿手性席夫碱配体中的6个氮原子配位形成八面体配位环境。每个结构基元中包含1个[Fe(L)3]2+阳离子和2个高氯酸根阴离子。由于铁(Ⅱ)中心周围手性配体的螺旋协调配位使[Fe(L)3]2+形成单一手性Λ构型。Fe(Ⅱ)-N键长表明配合物1和2中的铁(Ⅱ)在低自旋状态。在[Fe(L)3]2+中,相邻配体中的苯环和咪唑环形成分子内π-π相互作用。配合物1和2通过分子间C-H…π相互作用形成三维超分子结构。CD光谱证实配合物1和2在溶液中的光学活性。磁性测试表明配合物1和2分别在232和250 K发生自旋转换。由于配合物1和2具有相同的手性空间群和类似的堆积方式和分子间相互作用,导致1和2表现出不同自旋转换温度的原因主要是取代基效应。Two homochiral mononuclear spin-crossover iron（Ⅱ） complexes, namely, fac-Λ-[Fe（R-L1）3]（ClO4）2（1）, fac-Λ-[Fe（R-L2）3]（ClO4）2（2） have been successfully synthesized by subcomponent self-assembly of Fe（ClO4）2, 4-（imidazole-2-carboxaldehyde）butyronitrile and optical phenylethylamine derivatives. The two complexes have been determined by single-crystal X-ray diffraction analysis, elemental analysis, IR spectra,1H NMR spectra, UV spectra and CD spectra. X-ray crystallography revealed that the iron （Ⅱ） center in 1 and 2 assumed an octahedral coordination environment with six N donor atoms from three unsymmetrical bidentate chiral schiff-base ligands.Each unit contained one [Fe（L）3]2 ＋cation and two ClO4-anions. [Fe（L）3]2components were chiral with Λconfiguration due to the screw coordination arrangement of the chiral ligand around Fe （Ⅱ） centers. The Fe （Ⅱ）-N bond distances indicated that the Fe（Ⅱ） sites of 1 and 2 were in low-spin state. As for [Fe（L）3]2＋, intramolecular π-π interactions were present between phenyl group and imidazole ring of an adjacent ligand. In 1 and 2, 3D supramolecular architectures were formed through intermolecular C-H … π interactions. Circular dichromism spectra confirmed the presence of non-racemic chiral metal centers in solution for complexes 1 and 2. Magnetic measurements revealed that 1 and 2 displayed obviously spin-crossover behaviour at 232 and 250 K, respectively.Complexes 1 and 2 crystallized in the same chiral space group with similar packing modes and intermolecular interactions, therefore their different SCO bahaviors mainly resulted from substitution effect. CCDC： 1020956, 1;1020957, 2.

关 键 词：纯手性 自旋转换 铁(Ⅱ)配合物 席夫碱 

分 类 号：O614.811[理学—无机化学]