Abstract
Two new charge transfer salts of BEDT-TTF, bis (ethylenedithio) tetrathiafulvalene, with thiocyanato-metal complex anions have been synthesized and characterized as (BEDT-TTF)[Fe(NCS)]·CHCl and (BEDT-TTF)[Cr(NCS) (bipym)]·0.15HO, where bipym=2,2′-bipyrimidine. The Fe salt, I, crystallizes in the P-1 (No. 2) space group at 150 K with a=10.629(1) Å, b=12.099(1) Å, c=16.062(2) Å, α=99.61(1)°, β=90.87(1)°, γ=112.92(1)°, and V=1868.5(6) Å. At 150 K the Cr salt, II, crystallizes in the P-1 (No. 2) space group with a=9.243(2), b=11.781(2), c=22.925(5) Å, α=93.76(3), β=101.51(3), γ=105.45(3)°, V=2339.0(8) Å, and Z=2. Both salts exhibit close S···S contacts between the anion and cation components and in II there is no π-stacking between the bipym group and the BEDT-TTF molecules. Both salts are paramagnetic with C=4.926 I and C=1.819 II with small negative Weiss constants of -0.19 and -0.26, respectively. Therefore, the S···S contacts alone do not promote correlated magnetic effects as seen in other thiocyanato salts that also contain π-stacking. Each compound is a semiconductor and has two crystallographically independent BEDT-TTF molecules for which bond length analysis give charges of +0.9±0.1/+0.6±0.1 for I and +0.3±0.1/+0.9±0.1 for II. © 2001 Academic Press.