BAND STRUCTURES AND PHYSICAL-PROPERTIES OF NEW ORGANIC SALTS BASED ON UNSYMMETRICAL DONORS AND SQUARE-PLANAR DIANIONS

被引:8
作者
DUCASSE, L
MOUSDIS, G
FETTOUHI, M
OUAHAB, L
AMIELL, J
DELHAES, P
机构
[1] CTR RECH PAUL PASCAL,CNRS,F-33600 PESSAC,FRANCE
[2] UNIV RENNES 1,CHIM SOLIDE & INORGAN MOLEC LAB,CNRS,URA254,F-35042 RENNES,FRANCE
关键词
D O I
10.1016/0379-6779(93)90361-Y
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
Several organic salts based on the organic radical cations, MDTTTF (methylenedithio-tetrathiafulvalene), EDTTTF (ethylenedithio-tetrathiafulvalene) and EDOEDTTTF (ethylenedioxo-ethylenedithio-tetrathiafulvalene), have been prepared with the square planar dianions, M(CN)4 (M=Pt, Pd). We have determined their crystal structures and their physical properties (conductivity and ESR). The inclusion of solvent molecules in the crystal favors one-dimensional polymers built on the M(CN)4 anions and the solvent. This situation, which is found in the MDTTTF salts, is reminiscent of the crystal packing in the superconducting salt, (BEDTTTF)4Pt(CN)4H2O. It is important to note that the (MDTTTF)4Pt(CN)4 salts are the first kappa-phase observed in such materials. The salts based on the EDTTTF molecule belong to the beta-phase. The transport and magnetic properties of these compounds are contrasted. (MDTTTF)4Pt(CN)4(CH2Cl2)2 exhibits a quasi metallic behavior down to 170K where a broad metal-semiconductor regime change is detected. The temperature dependence of the ESR linewidth of (EDTTTF)4Pt(CN)4(H2O)2 does not ehibit any phase transition down to 4K, while a metal to insulator transition occurs in (EDTTTF)4Pd(CN)4(H2O)2 at 100K. The Pt and Pd salts of EDOEDTTTF are very similar and the poor quality of the crystals prevents any analysis for T<20K. Finally, the transfer integrals and band structures have been calculated in order to analyse these different behaviors.
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页码:1995 / 2000
页数:6
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