Molecular motion in pyridazinium/crown ether supramolecular cation salts of a nickel dithiolene complex
Molecular motion in pyridazinium/crown ether supramolecular cation salts of a nickel dithiolene complex
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DOI：
10.1039/c2dt32542j
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发表时间：
2013-01-01
影响因子：
4
通讯作者：
Nakamura, Takayoshi
中科院分区：
文献类型：
--
作者：
Liu, Zun-qi;Kubo, Kazuya;Nakamura, Takayoshi
在[Ni(dmit)(2)]（-）盐（其中dmit(2) = 2-硫酮-1,3-二硫酮-4,5-二硫酯）中引入了由单质子化吡啶嘧啶阳离子和顺-反-顺-二环己基- b[18]-冠-6 （DCH[18]-冠-6）或二苯并[18]-冠-6 （DB[18]-冠-6）形成的超分子阳离子。x射线晶体结构分析显示（吡啶鎓（+））（DCH[18]-crown-6）[Ni(dmit)(2)](-)(1)的DCH[18]-crown-6片段为椅子型构象。在（吡啶嗪（+））（DB[18]-crown-6）(2)[Ni(dmit)(2)](-)(H2O)(2)(2)(2)中观察到DB[18]-crown-6部分呈v形构象。吡啶鎓阳离子中的氮原子与DCH[18]-crown-6和DB[18]-crown-6的氧原子通过类似于O氢键的N-H+相互作用，分别形成1:1和1:1的超分子结构。盐1中存在足够的空间进行吡啶嗪离子的分子运动，即翻转和面内旋转。x射线分析观察到氮原子的无序性，表明吡嗪离子的动态运动，即触发器运动和面内运动。势能计算进一步支持了阳离子在晶体中动态运动的可能性。相比之下，盐2中吡啶基的翻转运动受到两个最邻近的DB[18]-冠-6分子的限制。在盐1的二维层中，观察到[Ni(dmit)(2)]（-）阴离子之间的弱反铁磁分子间相互作用，导致反铁磁海森堡链型磁化率交替存在。在盐2中观察到[Ni(dmit)(2)]（-）阴离子之间的准一维分子间相互作用，其磁性行为符合Bonner-Fisher模型。
Supramolecular cations formed by monoprotonated pyridazinium cations and cis-anti-cis-dicyclohexano-[18]-crown-6 (DCH[18]-crown-6) or dibenzo[18]-crown-6 (DB[18]-crown-6) were introduced into [Ni(dmit)(2)](-) salts (where dmit(2-) = 2-thione-1,3-dithiole-4,5-dithiolate). X-ray crystal structure analysis of (pyridazinium(+))(DCH[18]-crown-6)[Ni(dmit)(2)](-) (1) revealed a chair-type conformation of the DCH[18]-crown-6 moiety. A V-shaped conformation of the DB[18]-crown-6 moiety was observed in (pyridazinium(+))(DB[18]-crown-6)(2)[Ni(dmit)(2)](-)(H2O)(2) (2). Nitrogen atoms in the pyridazinium cations interacted with the oxygen atoms of the DCH[18]-crown-6 and DB[18]-crown-6 through N-H+similar to O hydrogen bonds, forming 1 : 1 and 1 : 2 supramolecular structures, respectively. Sufficient space for molecular motions of the pyridazinium cations, namely flip-flop and in-plane rotations, exists in salt 1. Disorder in nitrogen atoms was observed by X-ray analysis, indicating dynamic motion of the pyridazinium cation, namely flip-flop motion and in-plane motion. A potential energy calculation further supported the possibility of dynamic motion of cations in the crystal. By contrast, the flip-flop motion of the pyridazinium group in salt 2 is restricted by the two nearest-neighbouring DB[18]-crown-6 molecules. Weak antiferromagnetic intermolecular interactions between the [Ni(dmit)(2)](-) anions in the two-dimensional layers of salt 1 were observed, resulting in alternating antiferromagnetic Heisenberg chain-type magnetic susceptibility. Quasi-one-dimensional intermolecular interactions between the [Ni(dmit)(2)](-) anions were observed in salt 2, whose magnetic behaviour followed the Bonner-Fisher model.