Proposed Mechanism of Ferromagnetic Interaction of Organic Ferromagnets: 4-(Arylmethyleneamino)-2,2,6,6-tetramethylpiperidin-1-oxyls and Related Compounds
Proposed Mechanism of Ferromagnetic Interaction of Organic Ferromagnets: 4-(Arylmethyleneamino)-2,2,6,6-tetramethylpiperidin-1-oxyls and Related Compounds
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有机铁磁体铁磁相互作用的提出机制：4-(芳基亚甲基氨基)-2,2,6,6-四甲基哌啶-1-氧基及相关化合物
DOI：
10.1246/bcsj.69.1841
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发表时间：
1996
影响因子：
4
通讯作者：
K. Yamaguchi
中科院分区：
文献类型：
--
作者：
T. Nogami;T. Ishida;M. Yasui;F. Iwasaki;N. Takeda;M. Ishikawa;T. Kawakami;K. Yamaguchi
根据一系列有机自由基铁磁体的晶体结构和分子轨道计算，提出了一种可能的铁磁耦合机制。所研究的自由基是4-(arylmethyleneamino)-2，2，6，6-tetramethylpiperidin-1-oxyls(简写为Ar-CH=N-TEMPO，式中Ar=苯基、4-甲基硫苯基、4-氯苯基、4-联苯基和4-苯氧基苯基)和4-羟亚氨基-TEMPO。所有这些自由基晶体都具有这样的特征：在相邻分子的Tempo部分中，N-O自由基位的氧原子总是位于N-O的β位置的甲基和/或亚甲基氢原子附近。由于分子内的自旋极化，N-O自由基上的正自旋在β-氢原子上诱导负自旋，在(↑)-C(↓)-C(↑)-H(↓)上，这反过来又在相邻分子的N-O位上诱导正自旋。这种通过氢桥在N-O位之间进行铁磁耦合的自旋交替机制也适用于有机原子的情况。
A possible mechanism of ferromagnetic coupling of a series of organic radical ferromagnets is presented, based on their crystal structures and molecular-orbital calculations. The investigated radicals are 4-(arylmethyleneamino)-2,2,6,6-tetramethylpiperidin-1-oxyls (abbreviated as Ar–CH=N–TEMPO, where Ar = phenyl, 4-methylthiophenyl, 4-chlorophenyl, 4-biphenylyl, and 4-phenoxyphenyl), and 4-hydroxyimino-TEMPO. All of these radical crystals have characteristic features that oxygen atoms of N–O radical sites of TEMPO moieties always locate near methyl- and/or methylene-hydrogens at β-positions of N–O in the TEMPO moieties of adjacent molecules. A positive spin on the N–O radical induces negative spins on the β-hydrogen atoms due to an intramolecular spin-polarization, ON(↑)–C(↓)–C(↑)–H(↓), which in turn induces a positive spin on the N–O sites of the adjacent molecules. This spin-alternation mechanism of ferromagnetic coupling among N–O sites via hydrogen bridges is also applicable to the case of an organic ...