Role of Hydrogen Bonds in Benzimidazole-Based Organic Magnetic Materials: Crystal Scaffolding or Exchange Linkers?
Role of Hydrogen Bonds in Benzimidazole-Based Organic Magnetic Materials: Crystal Scaffolding or Exchange Linkers?
复制标题
氢键在苯并咪唑基有机磁性材料中的作用：晶体支架还是交换连接体？
DOI：
10.1021/cm010322h
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发表时间：
2001
影响因子：
8.6
通讯作者：
F. Palacio
中科院分区：
文献类型：
--
作者：
Jacqueline R. Ferrer;P. M. Lahti;C. George;P. Oliete;Andr'ea Julier;F. Palacio
合成了高度稳定的氮氧自由基5(6)-氯-2-（n -叔丁基- n -氨基氧基）苯并咪唑(4)和5,6-二甲基-2-（n -叔丁基- n -氨基氧基）苯并咪唑(5)，并用电子自旋共振光谱、晶体学和磁化率对其进行了表征。两者结晶为二聚体对，具有N - H氢键供体和N - O受体。这种行为与类似的2-（n-叔丁基- n-氨基氧基）苯并咪唑(3)形成氢键链形成对比（Ferrer， J. R.; Lahti， P. M.; George， C.; antrena， G.; Palacio， F. Chem）。材料学报。1999,11,2205−2210)。磁化率分析显示二聚体反铁磁交换耦合，J/k = - 22 k, 4 = - 24 k, 5 = - 24 k。密度泛函理论（DFT）计算支持一个N−O到N−O通过空间的反铁磁交换机制是4和5的整体磁性行为的主要贡献者。二聚体中−N−H···O−N氢键参与循环交换路径的自旋−极化交换耦合机制
The highly stable nitroxide radicals 5(6)-chloro-2-(N-tert-butyl-N-aminoxyl)benzimidazole (4) and 5,6-dimethyl-2-(N-tert-butyl-N-aminoxyl)benzimidazole (5) were synthesized and characterized by electron spin resonance spectroscopy, crystallography, and magnetic susceptibility. Both crystallize as dimeric pairs with N−H hydrogen bond donors and N−O acceptors. This behavior contrasts to that of analogous 2-(N-tert-butyl-N-aminoxyl)benzimidazole (3), which forms hydrogen-bonded chains (Ferrer, J. R.; Lahti, P. M.; George, C.; Antorrena, G.; Palacio, F. Chem. Mater. 1999, 11, 2205−2210). Susceptibility analysis shows dimeric antiferromagnetic exchange coupling with J/k = −22 K for 4 and −24 K for 5. Density functional theory (DFT) computations support a N−O to N−O throughspace antiferromagnetic exchange mechanism as the major contributor to the overall magnetic behavior of 4 and 5. A spin−polarization exchange coupling mechanism involving a cyclic exchange path using the −N−H···O−N hydrogen bonds in the dimer...