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The synthesis of a number pyrrolo-annelated tetrathiafulvalenes, including the parent bis(pyrrolo[3,4-d])tetrathiafulvalene (7) is decribed. Starting from readily available 4,5-bis(bromomethyl)-1, 3-dithiole-2-thione (14) and sodium tosylamide, the parent 7 and the asymmetric monopyrrolo tetrathiafulvalenes 23a,b were prepared in good yields via a nonclassical and simple pyrrole synthesis. Furthermore, a series of asymmetrical N-alkylated monopyrrolo/monodihydropyrrolotetrathiafulvalenes was prepared starting from primary amines and 14. A detailed study of the fundamental redox behavior of this class of heterocycles is reported. NMR spectroscopy, cyclic voltammetry, and PM3 MO calculations revealed that the pyrrolo-annelated tetrathiafulvalenes have highly extended pi-surfaces. The X-ray crystallographic analyses of the monopyrrolo tetrathiafulvalenes 22b and 24b, together with preliminary formation of a charge-transfer complex between the parent donor 7 and TCNQ, are also reported.

The title compound (4) was synthesized, and its crystalline structure was determined. The molecule has C 3 v point symmetry and crystallizes in the trigonal space group R3m. Crystal data for 4:  a = 16.6710(13) Å, b = 16.6710(13) Å, c = 4.2590(3) Å, α = β = 90°, γ = 120°, Z = 3, R(F) = 0.0234. The material has a permanent polarization and consequent pyroelectric properties. The room temperature pyroelectric coefficient was found to be −3 ± 2 μC m-2 K-1, which is in accordance with a calculated value of −3.2 μC m-2 K-1. The molecular dipole moment was determined to be 3.3 ± 0.2 D, the direction of which was unambiguously assigned with respect to the molecular coordinates. The thermal expansivity was determined at temperatures in the range −93 to 200 °C. The relative dielectric permittivity tensor was obtained at optical frequencies (ε11 and ε22 = 3.16 and ε33 = 2.48) and in the microwave region at 35 GHz (ε11 and ε22 = 5.2 ± 0.6 and ε33 = 2.9 ± 0.2), and at low frequencies (120 Hz and 1 kHz), the isotropic permittivity was determined (ε120  Hz = 4.7 ± 0.8 and ε1  kHz = 4.7 ± 1.1). Finally, an estimate of the molecular heat capacity was calculated (C p = 900 J Kg-1 K-1) and the material was considered for potential use in infrared detection as its detectivity merit factor, M r, was determined (M r = 8.8 × 10-2 m2 C-1).

The structure of 2C10H12SeX/2+.pF~ -, M r = 1041.06, a solid which exhibits superconductivity at 1.2 GPa below 0.9 K, has been determined at ambient pressure and temperature (295 K). (TMTSF)2PF 6 crystallizes in the triclinic space group P1 with a = 7.297 (1) mm-k Least-squares refinement of the structure gave R = 0.038 and R~ = 0.043 for 1466 reflections. The nearly planar TMTSF units are almost perpendicular to a (deviation 1.1 °) and form stacks along a. Within a stack the units repeat by an inversion leading to overlap displacements alternating in the direction of the long molecular axis and two independent interplanar distances of 3.63 and 3.66/k. The slight dimerization is clearly reflected in the intermolecular Se-Se distances. PF~ is centrosymmetric and shows considerable thermal motion.

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