北京大学学报(自然科学版)

混合价十二核锰配合物的合成、结构及磁性研究

安金1, 陈志达1, 卞江1, 高松1, 王诗玺1, 徐光宪1,陈久桐2   

  1. 1北京大学化学与分子工程学院,稀土材料化学及应用国家重点实验室;北京大学-香港大学稀土材料和生物无机化学联合实验室,北京,100871;2中国科学院福建物质结构研究所结构化学国家重点实验室,福州,350002
  • 收稿日期:1999-04-24 出版日期:2000-07-20 发布日期:2000-07-20

Synthesis, Structure and Magnetic Property Study on the Mixed Valence Dodenuclear Manganese Clusters

AN Jin1, CHEN Zhida1, BIAN Jiang1, GAO Song1, WANG Shixi1, XU Guangxian1, CHEN Jiutong2   

  1. 1The State Key Laboratory of Rare Earth Materials Chemistry and Applications; Department of Chemistry; Rare Earth Materials and Bio-inorganic Chemistry Laboratory of Peking University and Hongkong University; Peking University, Beijing, 100871, P.R. China; 2The State Key Laboratory of Structure Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, 350002, P.R. China
  • Received:1999-04-24 Online:2000-07-20 Published:2000-07-20

摘要: 合成了2个十二核锰的配合物[Mn12O12(3-Cl-C6H4CO2)16(H2O)3(3-Cl-C6H4CO2H)]·3-Cl-C6H4CO2H 1, 和[Mn12O12(CH3CO2)4(3-Br-C6H4CO2)12(H2O)4]·3-Br-C6H4CO2H·H2O 2。用X-射线衍射单晶分析法测定了配合物1的结构,其中心含有一个类立方体结构的[Mn4+4O4]+8, 这个簇芯被一非共面的8个Mn+3环及8个μ3-O所包围。配体是由16个桥连μ2-羧基和3个端基水、1个间氯苯甲酸组成。测定了配合物1,2变温直流磁化率,表明配合物1和2在低温时有较大的基态自旋;测定了配合物1,2的不同频率下的变温交流磁化率,以及在1.4K下外磁场从-5T到+5T的磁化强度曲线,在磁滞回线上均出现了2个台阶,表明配合物1和2存在分子自旋的量子隧穿,而且它们的共振磁化隧穿速度不同。简要讨论了配体和溶剂对十二核锰配合物磁性的影响。

关键词: 单分子磁体, 十二核锰配合物, 磁化率, 磁滞回线, 量子隧穿

Abstract: In order to explore the influence of the ligands and solvents on the magnetic properties of Mn12 complexes, the syntheses and magnetochemical properties of [Mn12O12(3-Cl-C6H4CO2)16(H2O)3(3-Cl-C6H4CO2H)]·3-Cl-C6H4CO2H 1, [Mn12O12(CH3CO2)4(3-Br-C6H4CO2)12(H2O)4] 2 have been studied. The crystal structure of the complex 1 has been characterized by X-ray diffraction method. The complex 1 crystallizes in the triclinic, space group of P1 with a=17.5779(3)A°,b=18.2712(3)A°,c=34.3616(5)A°,α=103.515(1)°,β=91.784(1)°,γ=116.25°,V=9508.5(3)A°3Z=2,Dc=1.294mg·m-3μ=1.085mm-1F(000)=3696, and S=1.096. It is found that the complex 1 consists of a central cubane-like [Mn4+4O4]+8 held within a nonplanar ring of eight Mn+3 ions and eight μ3-O2- ions. For both complexes 1 and 2 the χm signals are observed in the region 2~10K, measured at three different frequencies, and exhibit two-frequency dependent of χm AC peaks with a predominant peak in the 4~10K region. The magnetization hyteresis loops for the complexes 1 and 2 show the step-like character. These steps are attributable to the resonant magnetization tunneling. The affect of ligands and solvent on the magnetic properties of the title complexes are briefly discussed.

Key words: single molecule magnet, dodenuclear manganese cluster, magnetisability, hysteresis loop, the quantum tunneling

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