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°³，Z=2，D_c=1.294mg·m^-3，μ=1.085mm^-１，F(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-O^2- ions. For both complexes 1 and 2 the χ″_m signals are observed in the region 2～10K, measured at three different frequencies, and exhibit two-frequency dependent of χ″_m 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

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