Department of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry and Tianjin Key Laboratory of Metal and Molecule-based Material Chemistry, Nankai University, Tianjin 300071, China.
Dalton Trans. 2014 Feb 7;43(5):2234-43. doi: 10.1039/c3dt52959b.
Five new one-dimensional rare earth-nitronyl nitroxide radical complexes [Ln(hfac)3(NIT-3BrPhOMe)]n (Ln = Nd (1), Sm (2), Gd (3), Tb (4), Dy (5); hfac = hexafluoroacetylacetonate; NIT-3BrPhOMe = 2-(3'-bromo-4'-methoxyl)-4,4,5,5-tetramethyl-imidazolyl-1-oxyl-3-oxide) have been successfully prepared and structurally characterized. Five complexes possess linear chain structure in which the NIT-3BrPhOMe radical ligands link Ln(hfac)3 units through the oxygen atoms of nitronyl nitroxide groups. DC magnetic studies show that Nd, Sm and Gd complexes are paramagnetic above 2.0 K, whereas Tb and Dy complexes show antiferromagnetic ordering with T(N) = 19.9 K and 6.4 K, respectively. Moreover, Tb and Dy complexes exhibit frequency-dependence of ac magnetic susceptibilities, suggesting the presence of slow magnetic relaxation. This work demonstrated that the substituents of the nitronyl nitroxide radical and the lanthanide ion can play a crucial role in modulating the magnetic behavior for one-dimensional lanthanide-radical systems.
五种新的一维稀土-硝酰氮自由基配合物[Ln(hfac)3(NIT-3BrPhOMe)]n（Ln = Nd（1），Sm（2），Gd（3），Tb（4），Dy（5）；hfac = 六氟乙酰丙酮；NIT-3BrPhOMe = 2-(3'-溴-4'-甲氧基)-4,4,5,5-四甲基-咪唑基-1-氧-3-氧化物）已被成功制备并进行了结构表征。五个配合物具有线性链结构，其中 NIT-3BrPhOMe 自由基配体通过硝酰氮自由基基团的氧原子连接 Ln(hfac)3 单元。直流磁学研究表明，Nd、Sm 和 Gd 配合物在 2.0 K 以上为顺磁性，而 Tb 和 Dy 配合物分别表现出反铁磁有序，T(N) = 19.9 K 和 6.4 K。此外，Tb 和 Dy 配合物表现出交流磁化率的频率依赖性，表明存在缓慢的磁弛豫。这项工作表明，硝酰氮自由基和镧系离子的取代基可以在调节一维镧系-自由基体系的磁行为方面发挥关键作用。
