Rotational isomerism and crystal structure of 1,1'-dicyano- 1,1'-bicyclooctyl

Abstract

The dipole moment of 1,1'-dicyano-1,1'-bicyclooctyl (1) has been measured in carbon tetrachloride and benzene over a range of temperatures. Analysis of the relative permittivity data shows that at 25°C in carbon tetrachloride, the compound exists in 26% gauche and 74% trans. The experimentally derived values of the energy difference between the gauche and trans rotamers, the dihedral angle of the gauche rotamer and the gauche/trans population quotient are compared with values predicted by molecular mechanics calculations. The crystal structure of (1) has also been determined by single-crystal X-ray diffraction methods. The molecule crystallizes in the triclinic space group P1, a = 6.849(2) Å, b = 7.065(3) Å, c = 9.588(3) Å, α = 90.82(3)°, β = 105.42(2)°, γ = 118.26(2)°, V = 388.5(2) Å3, Z = 1. The molecule adopts the trans conformation in the crystalline state.