Synthesis of the new highest Tc ambient-pressure organic superconductor, κ-(BEDT-TTF)2Cu[N(CN)2]Br, by five different routes

The synthesis of new superconducting compounds is a topic of intense interest today. Very recently the superconducting transition temperature (Tc) of a new BEDT-TTF-based superconductor [BEDT-TTF or ET is bis(ethylenedithio)tetrathiafulvalene, C10H8S8], κ-(ET)2Cu[N(CN)2]Br, was raised to a new high for these systems (resistive onset Tc = 12.5 K, midpoint 11.2 K). Since the introduction of polymeric anions into the synthesis of ET-based materials and the development of useful structure-property correlations for β-phase ET superconductors, numerous new superconducting materials have been prepared. In this communication the authors report five synthetic routes, and the related solution chemistry, for the electrocrystallization of κ-(ET)2Cu[N(CN)2]Br. One of these syntheses, which is the easiest to use utilizes all commercially available materials