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合成了 2个十二核锰的配合物 [Mn12 O12 (3 Cl C6 H4 CO2 ) 16 (H2 O) 3(3 Cl C6 H4 CO2 H) ]·3 Cl C6 H4 CO2 H 1,和 [Mn12 O12 (CH3CO2 ) 4 (3 Br C6 H4 CO2 ) 12 (H2 O) 4 ]·3 Br C6 H4 CO2 H·H2 O 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 + 4 O4 ]+ 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的变温直流磁化率 ,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。
Two complexes of dodecane manganese [Mn12 O12 (3 Cl C6 H4 CO2) 16 (H2 O) 3 (3 Cl C6 H4 CO2 H)] · 3 Cl C6 H4 CO2 H 1 and [Mn12 O12 ( CH3CO2) 4 (3 Br C6 H4 CO2) 12 (H2 O) 4] 3 Br C6 H4 CO2 H H2 O2. The structure of complex 1 was determined by single crystal X-ray diffraction analysis. The center of the complex 1 was composed of [Mn4 + 4 O4] +8 with cubic structure. This cluster core was surrounded by a non-coplanar 8 Mn +3 rings and 8 μ3 O surrounded by. The ligand is composed of 16 bridges with 2 carboxyl groups and 3 terminal groups of water and 1 m-chloro-benzoic acid. The DC magnetic susceptibilities of complexes 1 and 2 were measured, indicating that the complexes 1 and 2 have large ground state spin at low temperature. The AC magnetization at different frequencies of complexes 1 and 2 were measured, The magnetization curves from-5T to + 5T for the external magnetic field under 4K show two steps on the hysteresis loop, indicating the quantum tunneling of molecular spins in complexes 1 and 2, and their resonant magnetization tunneling Different speed. The effects of ligands and solvents on the magnetic properties of dodecamethoxy manganese complexes are briefly discussed.