Tretyakov Eugene, Fokin Sergei, Romanenko Galina, Ikorskii Vladimir, Vasilevsky Sergei, Ovcharenko Victor
International Tomography Center, Siberian Branch of the Russian Academy of Sciences, 630090, Novosibirsk, Russia.
Inorg Chem. 2006 May 1;45(9):3671-8. doi: 10.1021/ic060132e.
Reactions between Cu(hfac)2 and nitronyl nitroxide biradicals 1,4-bis[4-(4,4,5,5-tetramethyl-3-oxide-1-oxyl-4,5-dihydro-1H-imidazol-2-yl)pyrazol-1-yl]butane (L4) and 1,8-bis[4-(4,4,5,5-tetramethyl-3-oxide-1-oxyl-4,5-dihydro-1H-imidazol-2-yl)pyrazol-1-yl]octane (L8) gave respectively a framework compound [Cu(hfac)2]2L4 and a layered polymer compound [Cu(hfac)2]2L8. The framework of [Cu(hfac)2]2L4 consists of 66-membered condensed metallocycles. Inside the framework, the structure has macrohelixes (pitch approximately 25 A) extending along the [001] crystallographic direction. All the helixes have the same direction of winding; the crystals, therefore, are optically active, the structure corresponding either to P-isomer (P4(1)2(1)2) or to M-isomer (P4(3)2(1)2). The long distances between the Cu atoms and the O atoms of the coordinated >N-O groups (Cu-O 2.351-2.467 A) are responsible for ferromagnetic exchange interactions in Cu2+-O-N< and >N-O-Cu2+-O-N< exchange clusters.
Cu(hfac)₂与氮氧自由基双自由基1,4 - 双[4 - (4,4,5,5 - 四甲基 - 3 - 氧化 - 1 - 氧代 - 4,5 - 二氢 - 1H - 咪唑 - 2 - 基)吡唑 - 1 - 基]丁烷（L4）以及1,8 - 双[4 - (4,4,5,5 - 四甲基 - 3 - 氧化 - 1 - 氧代 - 4,5 - 二氢 - 1H - 咪唑 - 2 - 基)吡唑 - 1 - 基]辛烷（L8）反应，分别得到一种骨架化合物[Cu(hfac)₂]₂L4和一种层状聚合物化合物[Cu(hfac)₂]₂L8。[Cu(hfac)₂]₂L4的骨架由66元稠合金属环组成。在骨架内部，结构具有沿[001]晶向延伸的大螺旋（螺距约25 Å）。所有螺旋具有相同的缠绕方向；因此，晶体具有光学活性，其结构对应于P - 异构体（P4(1)2(1)2）或M - 异构体（P4(3)2(1)2）。配位的>N - O基团的Cu原子与O原子之间的长距离（Cu - O 2.351 - 2.467 Å）导致了Cu²⁺ - O - N<和>N - O - Cu²⁺ - O - N<交换簇中的铁磁交换相互作用。
