Masuda Yuki, Kuratsu Masato, Suzuki Shuichi, Kozaki Masatoshi, Shiomi Daisuke, Sato Kazunobu, Takui Takeji, Hosokoshi Yuko, Lan Xiao-Zheng, Miyazaki Yuji, Inaba Akira, Okada Keiji
Department of Chemistry, Graduate School of Science, Osaka City University, Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan.
J Am Chem Soc. 2009 Apr 8;131(13):4670-3. doi: 10.1021/ja808093z.
Radical-substituted radical cations are attractive spin building blocks of molecule-based magnets. The introduction of an additional spin as a counteranion provides a unique three-spin system wherein the magnetic interactions between the spins of the radical substituent and the radical cation (J(intra)) and those between the spins of the radical cation and the anion (J(inter)) play decisive roles in determining the magnetic properties of the system. We report the first demonstration of a ferrimagnet by utilizing a large-J(intra) system, nitronyl nitroxide-substituted dihydrophenazine radical cation (NNDPP(+)) in combination with tetrabromoferrate (FeBr(4)(-)) as the counteranion. On the basis of measurements of dc and ac magnetic susceptibilities and heat capacity, the magnetic properties of NNDPP(+) x FeBr(4)(-) are elucidated to be those of a three-dimensional long-range-ordered ferrimagnet with T(c) = 6.7 K.
自由基取代的自由基阳离子是基于分子的磁体中具有吸引力的自旋构建块。引入额外的自旋作为抗衡阴离子提供了一个独特的三自旋系统，其中自由基取代基的自旋与自由基阳离子的自旋之间的磁相互作用（J(intra)）以及自由基阳离子的自旋与阴离子的自旋之间的磁相互作用（J(inter)）在决定系统的磁性方面起着决定性作用。我们报道了首次利用大J(intra)系统——硝酰基氮氧化物取代的二氢吩嗪自由基阳离子（NNDPP(+)）与四溴铁酸盐（FeBr(4)(-)）作为抗衡阴离子相结合来证明铁磁体。基于直流和交流磁化率以及热容量的测量，NNDPP(+) x FeBr(4)(-)的磁性被阐明为具有T(c) = 6.7 K的三维长程有序铁磁体的磁性。
