Hydrogen-Bonded Organic Ferromagnet
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- 作者：Michio M. Matsushita ; Akira Izuoka ; Tadashi Sugawara ; Tatsuya Kobayashi ; Nobuo Wada ; Naoya Takeda ; and Masayasu Ishikawa
- 刊名：Journal of the American Chemical Society
- 出版年：1997
- 出版时间：May 14, 1997
- 年：1997
- 卷：119
- 期：19
- 页码：4369 - 4379
- 全文大小：416K
- 年卷期：v.119,no.19(May 14, 1997)
- ISSN：1520-5126
文摘
Nitronyl nitroxide derivatives carrying a hydroquinone or aresorcinol moiety 2-(2',5'-dihydroxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl-3-oxide(HQNN) and 2-(3',5'-dihydroxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl 3-oxide (RSNN))have been designed and prepared. These compoundswere found to afford hydrogen-bonded crystals. In the case ofHQNN, two phases of crystals (
- and 
-HQNN)were obtained. Of these, the crystal structure of -HQNN ischaracterized by the intramolecular hydrogen bondbetween the o-hydroxy group and the nitronyl nitroxide andby the intermolecular one-dimensional hydrogen-bondedchain between the o- and p-hydroxy groups of theneighboring molecules, respectively. Two of thehydrogen-bonded chains run in parallel, and they are connected by the bifurcatedhydrogen bonds formed between the o-hydroxygroups of the facing molecules in the individual chain. The
T value of this crystal increased monotonouslywithlowering temperature (ST model, J = +0.93 K, 
=+0.46 K) and turned out to exhibit a ferromagnetic phasetransition at 0.5 K. On the basis of the heat capacity data,-HQNN was found to be a three-dimensional ferromagnet.On the other hand, the crystal of -HQNN was characterized bythe intermolecular hydrogen-bonded chain formedbetween the hydroxy group at the meta position and thenitronyl nitroxide and by the interchain 
- stacking.Themagnetic interaction of -HQNN was interpreted by the ferromagneticST model, and this ferromagnetic interaction(J = +5.0 K) was accompanied by a weak antiferromagneticinteraction ( = -0.32 K) at lower temperatures.Although the structural feature of the crystal of RSNN resemblesthat of the -HQNN, it exhibited the antiferromagneticinteraction predominantly (ST model, J = +10.0 K, = -4.0 K). These magnetic behaviors are consistentwithMcConnell's theory, when the spin densities at the interacting sitesconnected by hydrogen bonds are taken intoaccount. Thus, it may be concluded that the hydrogen bond plays arole not only in constructing hydrogen-bondedcrystals but also in transmitting spin polarization along the hydrogenbond.
- and -HQNN)were obtained. Of these, the crystal structure of -HQNN ischaracterized by the intramolecular hydrogen bondbetween the o-hydroxy group and the nitronyl nitroxide andby the intermolecular one-dimensional hydrogen-bondedchain between the o- and p-hydroxy groups of theneighboring molecules, respectively. Two of thehydrogen-bonded chains run in parallel, and they are connected by the bifurcatedhydrogen bonds formed between the o-hydroxygroups of the facing molecules in the individual chain. TheT value of this crystal increased monotonouslywithlowering temperature (ST model, J = +0.93 K, =+0.46 K) and turned out to exhibit a ferromagnetic phasetransition at 0.5 K. On the basis of the heat capacity data,-HQNN was found to be a three-dimensional ferromagnet.On the other hand, the crystal of -HQNN was characterized bythe intermolecular hydrogen-bonded chain formedbetween the hydroxy group at the meta position and thenitronyl nitroxide and by the interchain - stacking.Themagnetic interaction of -HQNN was interpreted by the ferromagneticST model, and this ferromagnetic interaction(J = +5.0 K) was accompanied by a weak antiferromagneticinteraction ( = -0.32 K) at lower temperatures.Although the structural feature of the crystal of RSNN resemblesthat of the -HQNN, it exhibited the antiferromagneticinteraction predominantly (ST model, J = +10.0 K, = -4.0 K). These magnetic behaviors are consistentwithMcConnell's theory, when the spin densities at the interacting sitesconnected by hydrogen bonds are taken intoaccount. Thus, it may be concluded that the hydrogen bond plays arole not only in constructing hydrogen-bondedcrystals but also in transmitting spin polarization along the hydrogenbond.