Acta Crystallographica Section B

Structural Science

Volume 52, Part 2 (April 1996)

research papers

Acta Cryst. (1996). B52, 384-387 [ doi:10.1107/S0108768195012286 ]

Structure of the charge-transfer salt 2,2',5,5'-tetraselenafulvalene-7,7,8,8-tetracyano-p-quinodimethane (TSeF-TCNQ)

P. W. R. Corfield and S. J. La Placa

Abstract: 2,2',5,5'-Tetraselenafulvalene-7,7,8,8-tetracyano-p-quinodimethane (1/1), TSeF-TCNQ, C₆H₄Se₄.C₁₂H₄N₄, M_r = 596.13, monoclinic, P2₁/c, a = 12.5048 (4), b = 3.8724 (2), c = 18.5041 (7) Å, = 104.131 (3)°, V = 868.9 Å³, T = 297 K, Z = 2, F(000) = 560, D_x = 2.28 Mg m^-3, (Cu K [alpha] ) = 1.5418 Å, = 115.7 cm^-1, R(F) = 0.018, wR(F) = 0.030 for 1393 unique reflections with (F²) > 3F². The crystals are isostructural with the corresponding tetrathiafulvalene salt, TTF-TCNQ, with both cations and anions arranged in segregated stacks parallel to b. There are SeN distances of 3.17 and 3.18 Å, along a, between cation and anion stacks, and HH distances of 2.58 Å, along c, between neighboring cation stacks, all shorter than the corresponding distances in TTF-TCNQ.