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The synthesis, X-ray and electronic structures of electroconducting radical ion salts based on organic donors (BETS and EDX-DMTTF (X=O, Se)) with inorganic counter-ions having photochromic properties are reported.

Periodical Density Functional (DFT) calculations were done on a hypothetical 1T-TaTe 2 phase in order to understand why this compound has not yet been synthetized. The combined analysis of the density of states and of the crystal orbital overlap populations have disclosed bands interaction that could be at the origin of the non existence of the 1T-TaTe 2 phase.

We report on transport properties of (EDT-TTF) 2 [Pd(dmit) 2 ] 2 . The occurence of a resistivity anomaly and of a metallic ground state, which is stabilized under pressure, is discussed within tight-binding band structure calculations.

The present work investigates the quasi-1D transport properties of the Ni (dmit) 2 -based compounds within a correlated, t-J model using the DMRG method. Strongly and weakly dimerized chains are studied by means of charge gap calculations ( IP-EA ) in order to extract the effective on-site repulsion term U for the Ni (dmit) 2 molecule.

The first example of a metallic charge-transfer salt derived from cis -bis(ethylenethio)-tetrathiafulvalene (BET-TTF) is reported. (BET-TTF) 2 SCN and (BET-TTF)SCN salts were obtained by electrocrystallization starting from trans -BET-TTF. X-ray crystal structure of the mixed-valence salt revealed that trans-cis isomerization occurs upon one electron oxidation. In spite of the structural disorder in both BET-TTF and the counterion, 2:1 salt is metallic down to 60 K and then resistance increases slowly down to 4K.

The resistivity hump which characterizes the 50 K metal-metal transition in (EDT-TTF) 2 [Pd(dmit) 2 ] 2 is shown to be associated with the condensation of a charge density wave ground state, as deduced from SQUID susceptibility and X-ray diffuse scattering measurements. Comparison between the observed CDW wavevector and the nesting properties of the calculated Fermi surfaces as a function of the electron transfer suggests that the charge transfer is approximately + 3 4 .