Crystal structure of a new conductive charge-transfer salt (TTM-TTF)Cu2Brx(x∼4.72) containing polymeric counter anions

The structure of a new conductive charge transfer salt was determined by X-ray diffraction method at room temperature. The crystal belongs to monoclinic, space group C 2/c with crystallographic parameters: a=27.817(9), b=4.0295(6), c=22.814(7) Å, β=117.98(4)°, V=2258.3(11) Å3, Z=4, dc=2.626 gcm−3, λ(MoKα)=0.71069 Å, μ=10.86 mm−1, F(000)=1291.84 and final R=0.076, Rw=0.076 for 1652 observed reflections. The structure consists of isolated 3,4;3′,4′-tetra(methylthio)-2,5;2′,5′-tetrathiafulvalene (TTM-TTF) of the organic donors and binuclear non-integer polybromide complex anions. Both the donors and the anions occupy symmetry centers in the cell and the TTM-TTF donors are stacked to form columns along the b axis with the shortest intra- and inter-columnar S···S contacts of 3.214(10) and 3.417(12) Å, respectively. 1,1′-di-μ-bromo-2,2′-dibromodicuprate moieties of the binuclear polybromide anions are stacked to form polymeric columns along b, in which the copper atoms are five-coordinate.