ELECTRICAL CONDUCTIVITIES AND CRYSTAL AND BAND-ELECTRONIC STRUCTURES OF A NEW PHASE OF BEDT-TTF-BROMIDE SALT, (BEDT-TTF)(2)BR(H2O)(3)

A new bromide salt of BEDT-TTF, (BEDT-TTF)(2)Br(H2O)(3), was obtained by an electrochemical crystallization of the tetrahydrofuran (THF) sol ution containing BEDT-TTF, malonic acid, and aqueous tetrabutylammoniu m hydroxide. Commercially available aqueous Bu4NOH contaminates Br-, w hich is the anion source of this salt. The temperature dependence of t he electrical resistance showed a complex behavior, but the resistance decrease in the low temperature range suggests a metallic ground stat e down to 4.2 K. Its crystal structure belongs to the delta-type, the example of which was found for delta-(BEDT-TTF)(2)AuBr2. A tight-bindi ng band structure calculation revealed a closed Fermi surface, charact eristic of a two-dimensional band structure. (C) 1998 Elsevier Science S.A. All rights reserved.