An Isomeric Series of Thiophene-Fused Tetracyanoquinodimethanes. III. Crystal Structures of Charge-Transfer Complexes with TTF

Abstract

Abstract 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, , a = 10.458(2), b = 9.852(2), c = 11.292(8) Å, α = 92.60(7), β = 113.64(6), γ = 97.38(6)°, V = 1051(2) Å3, Z = 2, Dx = 1.646 Mg m−3. For 3–TTF, triclinic, , a = 9.059(2), b = 8.459(2), c = 8.850(2) Å, α = 103.36(2), β = 115.76(2), γ = 106.30(2)°, V = 535.1(3) Å3, Z = 1, Dx = 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 Å for TTF–TTF, 3.49 Å for 1–1 and 3.36 Å for 1–TTF. In the crystals of 3–TTF the molecules form mixed stacks with the separation of 3.59 Å. The molecular geometry of TTF in the 1–TTF complex shows a TTF+ character, while that in 3–TTF shows a neutral type.