Novel Conductive Radical Cation Salts Based on Methylenediselenotetraselenafulvalene (MDSe-TSF): A Sign of Superconductivity in κ-(MDSe-TSF)2Br Below 4 K
✍ Scribed by Mie Kodani; Ayumi Takamori; Kazuo Takimiya; Yoshio Aso; Tetsuo Otsubo
- Book ID
- 102606807
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 301 KB
- Volume
- 168
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
Seven conductive radical cation salts based on MDSe-TSF (methylenediselenotetraselenafulvalene) have been synthesized by electrocrystallization in the presence of Cl À , Br À , I À 3 ; I 2 Br À , PF À 6 ; ClO À 4 ; and CuðNCSÞ À 2 counter anions. The crystal appearances of these salts fairly depend on the anions employed. X-ray crystallographic analyses have revealed that the PF 6 and ClO 4 salts in the shape of brown thin plates adopt the h-type structures characterized by the herringbone arrangement of donor stacks, whereas the Cl and Br salts in the shape of black thick plates favor the j-type structures with the orthogonal arrangement of donor dimers. Regardless of different crystal appearances or crystal packing patterns, all these salts show high conductivity (>10 2 S cm À1 ) at room temperature and retain metallic properties down to 4.2 K. Of them, the Br salt shows a weak but distinct diamagnetic shielding signal below 4 K in the dc magnetization measurement under zero-field-cooled (ZFC) condition, suggesting a sign of superconductivity. The band calculations of both PF 6 and Br salts demonstrate closed Fermi surfaces indicative of two-dimensional molecular conductors.