Mixed-valence, layered, cation radical salts of the ethane-bridged dimerictetrathiafulvalene [(EDT-TTF-CH2-)(2)(center dot+)] [X-][THF](0.5), X- = FeCl4-, GaCl4-

The synthesis and X-ray crystal structure of the ethane-linked dimeric tetr athiafulvalene [(EDT-TTF-CH2)(2)], 1,2-bis(ethylenedithiotetrathiafulvaleny l)ethane (1), is reported. It oxidizes reversibly at 0.45 and 0.90 V vs SCE . Electrocrystallization in the presence of [n-Bu4N][FeCl4] or [n-Bu4N][GaC l4] affords isostructural, mixed-valence conducting 1:1 salts [1(.+)][FeCl4 -][THF](0.5) and [1(.+)][GaCl4-][THF](0.5) whose X-ray crystal structures a re described. The intercalation of the tetrahedral anions within the organi c slabs and the resulting sliding of the molecular diads on top of each oth er give rise to both 1D- and 2D-type HOMO ... HOMO interactions whose origi n is correlated with the details of the peculiar overlap patterns obtained with those dimeric tetrathiafulvalenes. The weak paramagnetism observed in the GaCl4- salt due to the organic spins of the conducting slabs is hidden in the FeCl4- salt by the S = 5/2 Fe(III) contribution. The absence of siza ble magnetic interactions between the organic and FeCl4- sublattices is acc ompanied by weak antiferromagnetic FeCl4-/FeCl4- interactions, attributable to a short Cl ... Cl interanion distance at 3.419(17) Angstrom.