An organometallic half-sandwich supramolecular complex {K(18-Crown-6)(ηn-C6H5B(C6H5)3)} (n = 1–6) exhibiting a reversible breaking-symmetry phase transition and switchable dielectric behaviour
An organometallic half-sandwich supramolecular complex {K(18-Crown-6)(ηn-C6H5B(C6H5)3)} (n = 1–6) exhibiting a reversible breaking-symmetry phase transition and switchable dielectric behaviour
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有机金属半夹心超分子配合物 {K(18-Crown-6)(ηn-C6H5B(C6H5)3)} (n = 1−6) 表现出可逆破缺对称相变和可切换介电行为
DOI：
10.1039/c8dt04060e
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
Xiao-Ming Ren
中科院分区：
文献类型：
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作者：
Guo-Jun Yuan;Dong-Sheng Shao;Zhi-Yuan Yao;Wen-Long Liu;Xiao-Ming Ren
以1，4，7，10，13，16-六氧基环十八烷(18- ： -6)与四苯基硼钾(KBPh_4)的摩尔比为1：1，合成了一个超分子晶体，它含有一个有机金属半夹心超结构单元{K(18-冠-6)(ηn-C6H5B(C6H5)3)}(1，n=1-6)，并在∼211K出现可逆相变。高温相的293和423K表明，破坏对称性相变与[K(18-冠-6)]+的有序-无序转变和苯环配位方式向K+的转变有关。在约212K出现介电异常，在375K以上出现介电松弛。介电和热异常温度接近，介电松弛与[K(18-冠-6)]+和四苯基硼阴离子的相对位移有关。
A supramolecular crystal, built from a 1 : 1 molar ratio of potassium tetraphenylboron (KBPh4) with 1,4,7,10,13,16-hexaoxacyclooctadecane (18-Crown-6), contains an organometallic half-sandwich superstructure unit {K(18-Crown-6)(ηn-C6H5B(C6H5)3)} (1 with n = 1–6), and shows a reversible phase transition at ∼211 K. The analysis of crystal structures at 173 K in the low-temperature phase, and 293 and 423 K in the high-temperature phase revealed that the breaking-symmetry phase transition is associated with the order–disorder transformation of [K(18-Crown-6)]+ and the change of the coordination mode of the phenyl ring to K+. A dielectric anomaly appears at ca. 212 K and dielectric relaxation occurs above 375 K in 1. The dielectric and thermal anomaly temperatures are close to each other, and the dielectric relaxation is relevant to the relative displacement of [K(18-Crown-6)]+ and the tetraphenylboron anion.