Linear chain and mononuclear tri-spin compounds based on the lanthanide-nitronyl nitroxide radicals: structural design and magnetic properties
Linear chain and mononuclear tri-spin compounds based on the lanthanide-nitronyl nitroxide radicals: structural design and magnetic properties
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DOI：
10.1039/c1ce06016c
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发表时间：
2012
期刊：
影响因子：
3.1
通讯作者：
Yali Wang;Na Zhou;Yue Ma;Zifeng Qin;Qinglun Wang;Licun Li;P. Cheng;D. Liao
中科院分区：
文献类型：
--
作者：
Yali Wang;Na Zhou;Yue Ma;Zifeng Qin;Qinglun Wang;Licun Li;P. Cheng;D. Liao
合成了四种基于两个不同空间位阻的硝酰基氮氧自由基的稀土配合物，并对其结构和磁性进行了表征：[Ln（hfac）3（NITPhOEt）]n（Ce（1），Pr（2）; hfac =六氟乙酰丙酮; NITPhOEt = 4′-乙氧基苯基-4，4，5，5-四甲基咪唑啉-1-氧基-3-氧化物）; [Ln（hfac）3（NITPhOCH 2 Ph）2]（Ce（3），Pr（4）; NITPhOCH 2 Ph = 4′-苄氧基苯基-4，4，5，5-四甲基咪唑啉-1-氧基-3-氧化物）。X-射线晶体结构分析表明，配合物1和2具有类似的线性链状结构，Ln（hfac）3单元与NITPhOEt基团通过N-O键连接，配合物1和2具有较小的空间位阻。自由基的空间位阻较大，使配合物3和4形成单核三自旋配合物，中心Ln（III）离子分别与三个hfac和两个NITPhOCH 2 Ph自由基配位.变温磁化率的研究表明，有顺磁性离子（Ln（III）和自由基）之间的反铁磁相互作用在所有四个配合物。
Four Ln(III) complexes based on two nitronyl nitroxide radicals with different steric hindrance have been synthesized, characterized structurally and magnetically: [Ln(hfac)3(NITPhOEt)]n (Ce (1), Pr (2); hfac = hexafluoroacetylacetonate; and NITPhOEt = 4′-ethoxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide); [Ln(hfac)3(NITPhOCH2Ph)2] (Ce (3), Pr (4); NITPhOCH2Ph = 4′-benzyloxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide). The X-ray crystal structure analyses show that small steric hindrance of the radical makes complexes 1 and 2 show similar linear chain structures composed of Ln(hfac)3 units bridged by NITPhOEt radicals through their N–O groups. While the larger steric hindrance of the radical induces complexes 3 and 4 to be mononuclear tri-spin compounds, in which central Ln(III) ions are coordinated by three hfac and two NITPhOCH2Ph radicals. The variable-temperature magnetic susceptibility studies reveal that there are antiferromagnetic interactions between the paramagenetic ions (Ln(III) and radical) in all four complexes.