Control of Molecular Packing in the ET Based Conductor by Supramolecular Mellitate Networks (ET = Bis(ethylenedithio)tetrathiafulvalene)

Electrochemical oxidation of bis(ethylenedithio)terathiafulvalene (ET) with mellitic acid and pyridine in methanol produces a partially oxidized salt of [ET]3[C6(COO)6H42-]2[C5H5NH+]2·CH3OH·2H2O (1). In the crystal of 1, mellitate anions form a two-dimensional hydrogen-bonding double-sheet layer with pyridinium, methanol, and water. ET molecules are packed between the layers, forming a two-dimensional conducting sheet. The ET arrangement in the sheet resembles that in α-ET2I3, which has a metal-to-insulator transition. The transition into insulating states is completely suppressed in 1 due to the close packing of ET molecules in the supramolecular mellitate network.