Crystal structures and physical properties of new BDA-TTP conductors

摘要

The TaF6 and FeBr4 salts of BDA-TTP [2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene] have been prepared and characterized as beta-(BDA-TTP)(2)TaF6 and beta-(BDA-TTP)(2)FeBr4, respectively. The crystal structure of beta-(BDA-TTP)(2)TaF6 is isostructural to those of the ambient-pressure superconductors beta-(BDA-TTP)(2)X (X = SbF6, AsF6 and PF6), but this salt undergoes an MI (metal-to-insulator) transition instead of a superconducting transition at ambient pressure. The beta-(BDA-TTP)(2)FeBr4 salt, which is isomorphous to the superconductors beta-(BDA-TTP)(2)MCl4 (M = Fe and Ga) under applied pressures, exhibits a phase transition near 170 K and antiterromagnetic ordering with the Neel temperature (T-N) of about 9.5 K at ambient pressure.