CRYSTAL AND MOLECULAR-STRUCTURE OF THIENO[2'',3''/4',5']THIENO[2',3'-D]THIENO[3,2-B]THIOPHENE AS A HYDROGEN-POOR HETEROCYCLE

The crystal and molecular structure of the polythiophene 4 and its charge-transfer complex with tetracyanoquinodimethane (TCNQ) have been determined. Crystal data: 4, C10H4S4, M = 252.38, monoclinic, P2(1)/n, a = 11.462(1), b = 4.026(1), c = 10.437(1) angstrom, beta = 103.77(1)-degrees, V = 467.8(1) angstrom3, Z = 2, D = 1.792 g cm-3; 4.(TCNQ), C22H8N4S4, M = 456.60, triclinic, P1BAR, a = 7.533(1), b = 10.807(1), c = 7.094(2) angstrom, alpha = 90.12(2), beta = 92.13(2), gamma = 124.55(1)-degrees, V = 475.1(2) angstrom3, Z = 1, D = 1.596 g CM-3 . The molecules in the crystals of 4 are arranged in a zig-zag fashion along the diagonal line through the a and c axes, with notably short intermolecular S-S distances (3.482 and 3.526 angstrom). The occurrence of short S-S contacts, which are not observed in the lower homologues of the linearly-condensed polythiophenes 2 and 3, are discussed in terms of the low S:H ratio on the molecular periphery. A short S-S contact (3.604 angstrom) was also observed in the crystal of a 1:1 charge-transfer complex of 4 with TCNQ, which forms a mixed stack of donor and acceptor molecules.