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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.

The crystal and molecular structure of the highly conducting 1:1 charge-transfer salt 2, 3,6,4,5,7,8, was determined from diffractometer data. The unit cell is triclinic, space group Pi: a = 3. . Full-matrix least-squares refinement gave a final R = 0.039 for 2348 observed reflections measured by the w-scan technique on a four-circle diffractometer with graphite-monochromatized Mo Ktt radiation. The TMTSF cations and DMTCNQ anions form segregated, homologous stacks in the crystal with interplanar spacings of 3.64 and 3-31 A respectively. The planes of the ions are tilted in opposite directions relative to the short a axis. Their normals make an angle of 45-8 °. The interesting Se-N distance is 3.48 A, which is the longest distance reported so far for this class of materials. " Another important feature is the low symmetry of the DMTCNQ molecules, which modifies the stacking mode of the acceptor columns and may produce lower electron mobility.

The crystal and molecular structures of thiobenzophenone S-oxide, C~aHt0OS (TBPSO), and thiobenzophenone, CtaH~0S (TBP), were determined from diffractometer data. The unit cell of TBPSO is orthorhombic, space group P2~2~21; a = 5.903 (3)

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