Crystal structure and physical properties of radical cation salt based on 4,5-ethylenedioxy-4′-iodotetrathiafulvalene (EDO-TTF-I) with iodine bonding ability†,Materials Chemistry Frontiers

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Crystal structure and physical properties of radical cation salt based on 4,5-ethylenedioxy-4′-iodotetrathiafulvalene (EDO-TTF-I) with iodine bonding ability†
Materials Chemistry Frontiers ( IF 6.0 ) Pub Date : 2018-01-29 00:00:00 , DOI: 10.1039/c7qm00575j
Yoshiaki Nakano _{1,

2,

3,

4,

5} , Yusuke Takahashi _{1,

2,

3,

4,

5} , Kohdai Ishida _{1,

2,

3,

4,

5} , Manabu Ishikawa _{3,

6,

7,

8,

9} , Hideki Yamochi _{1,

2,

3,

4,

5} , Mikio Uruichi _{9,

10,

11}

Affiliation

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 (σ_RT = 5.3 S cm⁻¹ and E_a = 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|/k_B = 67.1 K and zJ′/k_B = −61.1 K. No splitting of the C [double bond, length as m-dash]

C stretching modes was observed in the range of 5–300 K by Raman spectroscopy, indicating a homogeneous charge distribution of EDO-TTF-I^0.5+. Therefore, (EDO-TTF-I)₂PF₆ is considered as a dimerized Mott insulator.

中文翻译：

具有碘键合能力的基于4,5-乙烯二氧基-4'-碘四硫富富瓦烯（EDO-TTF-I）的自由基阳离子盐的晶体结构和物理性质†

通过从乙腈中重结晶并在正交晶系中以空间群Pbca进行结晶，获得了具有碘键合能力的4,5-乙二氧基-4'-碘四硫富富瓦烯（EDO-TTF-1）单晶。弯曲的EDO-TTF-1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。在含有六氟磷酸四丁基铵（TBA）PF _6的无水乙醇中对EDO-TTF-1进行电结晶，得到（EDO-TTF-1）₂ PF _6的单晶。X射线结构分析表明，EDO-TTF-1分子以头到尾的方式形成二聚化的堆积柱，这被称为β'型排列。EDO-TTF-1和PF ₆之间的碘键观察到EDO-TTF-1分子之间存在阴离子和短的I⋯S接触。紧束缚带计算表明，强分子二聚化将能带分为具有小的能隙的上带和下带，其中上带有效地被半填充。结果发现，（EDO-TTF-I）₂ PF ₆是半导体的（σ _RT = 5.3小号厘米^-1和Ë_一个= 0.17 eV）的并显示出让人联想到一个低维局部自旋系统的磁特性。磁数据通过结合链间相互作用的Bonner-Fisher模型进行了分析：J | / k _B = 67.1 K和zJ '/ k_B =^-61.1K。 [双键，长度为m-破折号]