AN ISOMERIC SERIES OF THIOPHENE-FUSED TETRACYANOQUINODIMETHANES .3. CRYSTAL-STRUCTURES OF CHARGE-TRANSFER COMPLEXES WITH TTF

The crystal structures of the charge-transfer complexes of two isomeric thiophene-fused TCNQs, 4,8-bis(dicyanomethylene)-4,8-dihydrobenzo[1,2-b:4,5-b']dithiophene (1), and [1,2-b:4,5-c'] isomer (3) with tetrathiafulvalene (TTF) have been determined by the X-ray method. For 1-TTF, triclinic, P1BAR, a=10.458(2), b=9.852(2), c=11.292(8) angstrom, alpha=92.60(7), beta=113.64(6), gamma=97.38(6)-degrees, V=1051(2) angstrom3, Z=2, D(x)=1.646 Mg m-3. For 3-TTF, triclinic, P1BAR, a=9.059(2), b=8.459(2), c=8.850(2) angstrom, alpha=103.36(2), beta=115.76(2), gamma=106.30(2)-degrees, V=535.1(3) angstrom3, Z=1, D(x)=1.616 Mg M-3. The final R values are 0.079 for 3437 observed reflections and 0.048 for 1937 observed reflections for 1-TTF and 3-TTF, respectively. The crystal structure of 1-TTF complex is composed of TTF pairs and TCNQ pairs. These pairs stack alternately with each other. The mean distances between molecular planes are: 3.62 angstrom for TTF-TTF, 3.49 angstrom for 1-1 and 3.36 angstrom for 1-TTF. In the crystals of 3-TTF the molecules form mixed stacks with the separation of 3.59 angstrom. The molecular geometry of TTF in the 1-TTF complex shows a TTF+ character, while that in 3-TTF shows a neutral type.