Molecular motion of halogenated ethylammonium/[18]crown-6 supramolecular ions in nickel dithiolate magnetic crystals
Molecular motion of halogenated ethylammonium/[18]crown-6 supramolecular ions in nickel dithiolate magnetic crystals
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DOI：
10.1039/d1ce00253h
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发表时间：
2021-03-10
期刊：
影响因子：
3.1
通讯作者：
Nakamura，Takayoshi
中科院分区：
文献类型：
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作者：
Hasuo，Naohiro;Takahashi，Kiyonori;Nakamura，Takayoshi
由乙基铵衍生物（X-CH 2CH 2-NH3+）与[18]冠-6络合组成的超分子阳离子被掺入[Ni（dmit）2]−晶体中，以促进分子运动。为此目的，制备了（X-CH 2CH 2-NH3+）（[18]冠-6）[Ni（dmit）2]−（1：X = H，2：X = F，3：X = Cl和4：X = Br）的晶体。虽然大幅度分子运动不发生在晶体1中，动态无序的F-CH 2基团发生在晶体2中的两个位置之间。在晶体3中也存在类似的Cl-CH 2基团随[18]冠-6分子的旋转而沿着的无序。晶体4显示Br-CH 2-CH 2基团在四个位点之间的动态无序。对于晶体4来说尤其如此，它经历了明显的介电响应，在介电损耗角正切的温度依赖性中具有类似松弛的行为。所有晶体中[Ni（dmit）2]−离子之间的相互作用都是反铁磁的，并且相互作用的大小与从转移积分估计的分子间相互作用的强度定性一致，其中[Ni（dmit）2]−二聚体内的相互作用大于所有晶体中的其他相互作用。
Supramolecular cations, consisting of ethylammonium derivatives (X–CH2CH2–NH3+) complexed with [18]crown-6, were incorporated into [Ni(dmit)2]− crystals in order to promote molecular motion. Crystals of (X–CH2CH2–NH3+)([18]crown-6)[Ni(dmit)2]− (1: X = H, 2: X = F, 3: X = Cl and 4: X = Br) were prepared for this purpose. Although large amplitude molecular motions do not occur in crystal 1, dynamic disorder of F–CH2 groups takes place between two sites in crystal 2. Similar disorder of Cl–CH2 groups along with rotation of [18]crown-6 molecules also exists in crystal 3. Crystal 4 exhibits dynamic disorder of Br–CH2–CH2 groups between four sites. This is especially the case for crystal 4 which undergoes a distinct dielectric response with relaxer-like behavior in the temperature dependence of the dielectric loss tangent. Interactions between [Ni(dmit)2]− ions in all crystals are antiferromagnetic, and the magnitudes of the interactions are qualitatively consistent with the strength of intermolecular interactions estimated from transfer integrals, where interactions within [Ni(dmit)2]− dimers are the larger than the others in all crystals.