A new compound in the BEDT-TTF family [BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene] with a tetrathiocyanatocuprate(II) anion, (BEDT-TTF)4[Cu(NCS)4]

Abstract

A new phase combining BEDT-TTF and [Cu(NCS)4]2– as the counter-anion, namely bis[bis(ethylenedithio)tetrathiafulvalenium] tetrathiocyanatocuprate(II) bis[bis(ethylenedithio)tetrathiafulvalene], (C10H8S8)2[Cu(NCS)4]·2C10H8S8 or (BEDT-TTF)4[Cu(NCS)4] was obtained during a galvanostatic electrocrystallization process. As previously observed with BEDT-TTF-based compounds with oxalatometallate anions, the BEDT-TTF molecules in (BEDT-TTF)4[Cu(NCS)4] exhibit the so-called pseudo-κ arrangement, with two BEDT-TTF molecules being positively charged and two electronically neutral. The bond lengths and angles in the two unique BEDT-TTF molecules differ slightly. The crystal structure consists of layers of BEDT-TTF molecules extending parallel to (001). The width of this layer corresponds to the length of the a axis [16.9036 (17) Å]. The BEDT-TTF layers are separated by layers of centrosymmetric square-planar [Cu(NCS)4]2– dianions.

Keywords

• crystal structure
• BEDT-TTF
• Cu(NCS)2
• superconductor
• pseudo-κ arrangement