Trifluoromethylsulfonyl-Based Salts of BEDT-TTF: Crystal and Electronic Structures and Physical Properties11

• Published in: Journal of solid state chemistry 2002-11, Vol.168 (2), p.524-534
• Main Authors: Schlueter, John A., Geiser, Urs, Wang, H.Hau, Kini, Aravinda M., Ward, Brian H., Parakka, James P., Daugherty, Roxanne G., Kelly, Margaret E., Nixon, Paul G., Winter, Rolf W., Gard, Gary L., Montgomery, Lawrence K., Koo, H.-J., Whangbo, M.-H.
• Format: Article
• Language: English
• Subjects: BEDT-TTF; charge transfer salt; electrical conductivity; trifluoromethylsulfonyl anions
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1006/jssc.2002.9750

Three 2 : 1 salts of the organic donor molecule bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET) with trifluoromethylsulfonyl-based anions N(SO 2CF 3) 2 −, CH(SO 2CF 3) 2 − and C(SO 2CF 3) 3 − were prepared by electrocrystallization. These salts were characterized by single-crystal X-ray diffraction, electron spin resonance (ESR) spectroscopy, electrical resistivity measurements and electronic band structure calculations. (ET) 2N(SO 2CF 3) 2 is a two-dimensional (2D) metal, but its ESR spin susceptibility above 150 K shows a weakly semiconducting behavior, presumably because during ESR measurements the sample cooling rate is slow hence allowing the disordered anions to readjust their positions. (ET) 2CH (SO 2CF 3) 2 is a 2D metal and undergoes a metal-to-insulator (MI) transition at 110 K due probably to a geometry change of the donor molecule layers. (ET) 2C(SO 2CF 3) 3 is a one-dimensional (1D) metal and undergoes an MI between 180 and 240 K, which is expected to be of charge density wave type.