Crystal structure and physical properties of radical cation salt based on 4,5-ethylenedioxy-4’-iodotetrathiafulvalene (EDO-TTF-I) with iodine bonding ability
Crystal structure and physical properties of radical cation salt based on 4,5-ethylenedioxy-4’-iodotetrathiafulvalene (EDO-TTF-I) with iodine bonding ability
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具有碘键合能力的4,5-亚乙基二氧基-4-碘四硫富瓦烯（EDO-TTF-I）自由基阳离子盐的晶体结构和物理性质
DOI：
10.1039/c7qm00575j
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
M. Uruichi
中科院分区：
文献类型：
--
作者：
Y. Nakano;Y. Takahashi;K. Ishida;M. Ishikawa;H. Yamochi;M. Uruichi
通过乙腈重结晶得到具有碘键合能力的4,5-亚乙基二氧基-4′-碘四硫富瓦烯(EDO-TTF-I)单晶，并在空间群为Pbca的斜方晶系中结晶。弯曲的EDO-TTF-I分子形成二聚体结构，并且在二聚体之间观察到短的I⋯O接触。 EDO-TTF-I在含有六氟磷酸四丁基铵(TBA)PF6的无水乙醇中电结晶，得到(EDO-TTF-I)2PF6的单晶。 X射线结构分析表明，EDO-TTF-I分子以头尾相接的方式形成二聚堆积柱，即β'型排列。观察到 EDO-TTF-I 和 PF6 阴离子之间的碘键以及 EDO-TTF-I 分子之间的短 I⋯S 接触。紧束缚能带计算表明，强分子二聚化将能带分成能隙较小的上能带和下能带，其中上能带实际上是半填充的。研究发现 (EDO-TTF-I)2PF6 具有半导体性质（σRT = 5.3 S cm−1 且 Ea = 0.17 eV），并表现出让人想起低维局域自旋系统的磁性。通过结合链间相互作用的 Bonner-Fisher 模型分析磁性数据：|J|/kB = 67.1 K 和 zJ′/kB = -61.1 K。拉曼光谱在 5-300 K 范围内没有观察到 CC 拉伸模式的分裂，表明 EDO-TTF-I0.5+ 具有均匀的电荷分布。因此，(EDO-TTF-I)2PF6被认为是二聚莫特绝缘体。
Single crystals of 4,5-ethylenedioxy-4′-iodotetrathiafulvalene (EDO-TTF-I) with iodine bonding ability were obtained by recrystallization from acetonitrile and crystallized in the orthorhombic system with the space group Pbca. Bent EDO-TTF-I molecules formed the dimer structure, and a short I⋯O contact was observed between dimers. Electrocrystallization of EDO-TTF-I in absolute ethanol containing tetrabutylammonium hexafluorophosphate, (TBA)PF6, afforded single crystals of (EDO-TTF-I)2PF6. An X-ray structural analysis revealed that EDO-TTF-I molecules form dimerized stacking columns in a head-to-tail manner, which is referred to as a β′-type arrangement. Iodine bonds between EDO-TTF-I and PF6 anions and short I⋯S contacts between EDO-TTF-I molecules were observed. Tight-binding band calculations indicated that the strong molecular dimerization splits the energy band into upper and lower bands with a small energy gap, where the upper band is effectively half-filled. It was found that (EDO-TTF-I)2PF6 is semiconducting (σRT = 5.3 S cm−1 and Ea = 0.17 eV) and exhibits magnetic properties reminiscent of a low-dimensional localized spin system. The magnetic data were analyzed by the Bonner–Fisher model incorporating interchain interactions: |J|/kB = 67.1 K and zJ′/kB = −61.1 K. No splitting of the CC stretching modes was observed in the range of 5–300 K by Raman spectroscopy, indicating a homogeneous charge distribution of EDO-TTF-I0.5+. Therefore, (EDO-TTF-I)2PF6 is considered as a dimerized Mott insulator.