Dimerization Effect on the Physical Properties in New One-Dimensional Organic Conductors: (ChTM-TTP)2AuBr2, (ChTM-TTP)2GaCl4, and (ChTM-TTP)ReO4
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- Tadashi Kawamoto
- Department of Organic and Polymeric Materials, Graduate School of Science and Engineering, Tokyo Institute of TechnologyO-okayama, Meguro-ku, Tokyo 152-8552
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- Minoru Ashizawa
- Department of Organic and Polymeric Materials, Graduate School of Science and Engineering, Tokyo Institute of TechnologyO-okayama, Meguro-ku, Tokyo 152-8552
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- Takehiko Mori
- Department of Organic and Polymeric Materials, Graduate School of Science and Engineering, Tokyo Institute of TechnologyO-okayama, Meguro-ku, Tokyo 152-8552
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- Jun-Ichi Yamaura
- Institute for Solid State Physics, The University of TokyoKashiwanoha, Kashiwa-shi, Chiba 277-8581
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- Reizo Kato
- RIKEN, The Institute of Physical and Chemical ResearchHirosawa, Wako-shi, Saitama 351-0198
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- Yohji Misaki
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto UniversityYoshida, Kyoto 606-8501
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- Kazuyoshi Tanaka
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto UniversityYoshida, Kyoto 606-8501
説明
<jats:title>Abstract</jats:title> <jats:p>Crystal structure analyses, measurements of transport and magnetic properties, and low-temperature X-ray studies of new organic conductors: (ChTM-TTP)2AuBr2, (ChTM-TTP)2GaCl4, and (ChTM-TTP)ReO4, where ChTM-TTP is 2-[4,5-(1,2-cyclohexylenedithio)-1,3-dithiol-2-ylidene]-5-[4,5-bis (methylthio)-1,3-dithiol-2-ylidene]-1,3,4,6-tetrathiapentalene, have been carried out. In these compounds, the donors form quasi-one-dimensional columns with dimerization induced by the steric hindrance of the 1,2-cyclohexylene unit. The crystal structures and the energy band structures of both AuBr2- and GaCl4- salts are similar to those of the Bechgaard salts. The electrical resistivity and the thermoelectric power show metallic behavior above 100 K for the AuBr2- salt and above 150 K for the GaCl4- salt. The results of the ESR spin susceptibility, the static magnetic susceptibility, and the low-temperature X-ray studies indicate that the ground states of both salts are antiferromagnetic insulators. The Néel temperatures are about 38 K for the AuBr2- salt and about 32 K for the GaCl4- salt. These salts are the first materials showing an antiferromagnetic state among the TTP series conductors. In (ChTM-TTP)2X (X = Au(CN)2, AuBr2, and GaCl4), the strength of the dimerization is related to the charge localization temperature. For the ReO4- salt, the donor to anion ratio is 1 : 1 in spite of the tetrahedral anion being similar to the GaCl4- anion. Although the interstack interactions are not small, the degree of charge transfer of the donor molecule is +1; thus this salt has an energy gap at the Fermi level, in agreement with the semiconducting transport behavior.</jats:p>
収録刊行物
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- Bulletin of the Chemical Society of Japan
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Bulletin of the Chemical Society of Japan 75 (3), 435-447, 2002-03-01
Oxford University Press (OUP)
