CRYSTAL-STRUCTURE OF 4'-PENTYL-4-CYANOBIPHENYL (5CB)

The crystal structure and the molecular arrangement of 4'-pentyl-4-cya nobiphenyl (5CB) at 253 K are described. At 253 K the compound crystal lized from pure ethanol as plates, as well as fine needles, both colou rless. The crystal data for both crystal habits are within experimenta l error identical. The data for the plates were measured as: a = 8.249 (5) Angstrom, b = 16.022(4) Angstrom, c = 10.935(3) Angstrom beta = 95 .09(3)degrees, space group P2(1)/a. Considering 2014 independent refle ctions, the structure was refined to a final R value of 0.0588. In the case of the needles, with 1892 independent reflections, R converged t o 0.0503. The torsion angle between the normals of the benzene rings i n the biphenyl moiety was -26.3(3)degrees. Within the aliphatic chain an all-trans conformation was given, but the orientation of the pentyl group relative to the plane of the attached aromatic ring was nearly vertical (-90.5(3)degrees). The structure obtained is discussed in com parison with the lower homologues 1CB up to 4CB.