| 基于双齿咪唑席夫碱配体的两个手性自旋转换铁(Ⅱ)配合物 | |
| Two Homochiral Spin-Crossover Iron(Ⅱ) Complexes Based on Bidentate Imidazole Schiff Base Ligands | |
| 摘要: 以含有苯环和咪唑环的手性双齿席夫碱为配体, 合成了2个纯手性单核自旋转换铁(Ⅱ)配合物fac-Δ-[Fe(S-L1)3][ClO4]2 (1), mer-Λ-[Fe(R-L2)3][ClO4]2·Et2O (2)(L1=1-对氯苯基-N-(1-正丙烯基-1H-咪唑-2-亚甲基)乙胺;L2=1-苯基-N-(1-异丙烯基-1H-咪唑-2-亚甲基)乙胺)。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配合物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。配合物1中每个结构基元中包含1个[Fe(Ln)3]2+阳离子和2个高氯酸根阴离子。而配合物2中每个结构基元中包含2个[Fe(Ln)3]2+阳离子、4个高氯酸根阴离子和1个乙醚分子。由于铁(Ⅱ)中心周围手性配体的螺旋协调配位使[Fe(Ln)3]2+形成单一构型。Fe(Ⅱ)-N键长表明配合物1中的铁(Ⅱ)在低自旋状态, 而配合物2中的铁(Ⅱ)在高自旋状态。在[Fe(Ln)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和C-Cl…π相互作用形成超分子结构。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372 K和146 K发生自旋转换。由于配合物1和2具有不同的堆积方式和分子间相互作用, 导致1和2表现出不同的自旋转换温度。 | |
| 关键词: 纯手性 自旋转换 铁(Ⅱ)配合物 席夫碱 | |
| 基金项目: 国家自然科学基金(No.21101078, 21276105), 新世纪优秀人才计划(No.NCET-11-0657), 江苏省双创团队资助项目。 | |
| Abstract: Based on the bidentate schiff base ligands involving phenyl and imidazole groups, two homochiral mononuclear spin-crossover iron(Ⅱ) complexes, fac-Δ-[Fe(S-L1)3][ClO4]2 (1), mer-Λ-[Fe(R-L2)3][ClO4]2·Et2O (2) (L1=1-parachlorophenyl-N-(1-n-propylenyl-1H-imidazol-2-ylmethylene)ethanamine; L2=1-phenyl-N-(1-iso-butenyl-1H-imidazol-2-ylmethylene)ethanamine) have been synthesized. 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 6 N donor atoms from three unsymmetrical bidentate chiral schiff base ligands. Each unit contained one [Fe(Ln)3]2+ cation and two ClO4- anions in 1. While 2 contained two [Fe(Ln)3]2+ cation, four ClO4- anions and one diethyl ether molecular. [Fe(Ln)3]2+ components were chiral with single configuration 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 were in low-spin state, while the Fe(Ⅱ) centers of 2 were in high-spin state. As for [Fe(Ln)3]2+, intramolecular π-π interactions were present between phenyl group and imidazole ring of an adjacent ligand. In 1 and 2, supramolecular architectures were formed through intermolecular C-H…π and/or C-Cl…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 372 K and 146 K, respectively. Complexes 1 and 2 crystallized in different packing modes and intermolecular interactions, therefore their SCO bahaviors were different. | |
| Keywords: homochiral spin-crossover iron(Ⅱ) complexes schiff base | |
| 投稿时间：2015-03-04 修订日期：2015-05-08 | |
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| 顾玲,任冬红,刘志明,孙晓利,邱丹,顾志国,李在均.基于双齿咪唑席夫碱配体的两个手性自旋转换铁(Ⅱ)配合物[J].无机化学学报,2015,31(7):1357-1364. | |
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