Unusual Magnetic Properties of One-Dimensional Molecule-Based Magnets Associated with a Structural Phase Transition
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- 作者：Xiaoming Ren ; Qingjin Meng ; You Song ; Changsheng Lu ; Chuanjiang Hu ; and Xiaoyuan Chen
- 刊名：Inorganic Chemistry
- 出版年：2002
- 出版时间：November 4, 2002
- 年：2002
- 卷：41
- 期：22
- 页码：5686 - 5692
- 全文大小：206K
- 年卷期：v.41,no.22(November 4, 2002)
- ISSN：1520-510X
文摘
Three ion-pair complexes, [RbzPy]+[Ni(mnt)2]- (mnt2- = maleonitriledithiolate; [RbzPy]+ = 4-R-benzylpyridinium;R = Br (1), Cl (2), and NO2 (3)), with unusual magnetic properties have been synthesized and characterized. Thecrystal structures of 1 and 2 have been solved. The two complexes belong to the P21/c space group with Z = 4and C20H11BrN5NiS4, a = 12.0744(17) Å, b = 26.369(4) Å, c = 7.440(3) Å, and 
= 102.63(3)
for 1 and C20H11ClN5NiS4, a = 12.105(2) Å, b = 26.218(4) Å, c = 7.374(2) Å, and = 102.55(2) for 2, respectively. The[Ni(mnt)2]- anions in 1-3 form uniformly spaced one-dimensional (1-D) magnetic chains of s = 1/2 at roomtemperature. The temperature dependences of the susceptibility for 1-3 show that they undergo phase transitions.All three complexes are paramagnetic in their high-temperature (abbreviation HT) phase and diamagnetic in thelow-temperature (abbreviation LT) phase because of strong dimerization along the stacking direction. The resultsof thermal analysis (DSC) further confirm that the phase transition for 1 and 2 is first-order but maybe second-order for 3. The phenomena observed in this study are similar to those of the 1-D radical systems.
= 102.63(3) for 1 and C20H11ClN5NiS4, a = 12.105(2) Å, b = 26.218(4) Å, c = 7.374(2) Å, and = 102.55(2) for 2, respectively. The[Ni(mnt)2]- anions in 1-3 form uniformly spaced one-dimensional (1-D) magnetic chains of s = 1/2 at roomtemperature. The temperature dependences of the susceptibility for 1-3 show that they undergo phase transitions.All three complexes are paramagnetic in their high-temperature (abbreviation HT) phase and diamagnetic in thelow-temperature (abbreviation LT) phase because of strong dimerization along the stacking direction. The resultsof thermal analysis (DSC) further confirm that the phase transition for 1 and 2 is first-order but maybe second-order for 3. The phenomena observed in this study are similar to those of the 1-D radical systems.