Supramolecular organic conductor θ-(DIETS)₂[Au(CN)₄]: Unique crystal structure and superconductivity under uniaxial strain (DIETS = diiodo(ethylenedithio)diselenadithiafulvalene)

The I⋯N type intermolecular interaction is highly useful for the control of the molecular arrangement in organic crystals. One of the strategies for the application of the iodine-based interaction to organic conductors is the utilization of iodine-bonded TTFs and metal-cyanate anions. Among them, the Au(CN)₄ salt of an exotic donor molecule "diiodo(ethylenedithio)diselenadithiafulvalene" (DIETS) crystallizes in a so-called θ-type molecular packing of the conducting layer tailored by the I⋯N type donor⋯anion interaction. In contrast to the common θ-salts of BEDT-TTF, the temperature of the metal-insulator transition was lowered under hydrostatic pressure. On the other hand, under the uniaxial strain up to 10kbar, we observed an abrupt drop of the resistivity around 8K and the recovery of the resistance in a magnetic field is characteristic of the superconducting state.