The crystal and molecular structure of syn-9-phenyl-2,11-dithia[3,3]metacyclophane

The crystal structure of syn-9-phenyl-2,11-dithia[3,3]metacyclophane, 6, has been determined by single crystal X-ray diffraction and refined to an R value of 0.0723. The crystal structure is triclinic with a = 9.573(2), b = 12.010(4), c = 8.433(2) Å, α = 108.02(2)°, β = 95.95(2)°, γ = 102.25(3)°, and the space group is [Formula: see text] with two molecules per cell, D (meas) = 1.313 g cm −3 , D (calc) = 1.306 g cm −3 . The bridging S atoms differ in their conformations so that the S … S distance is 6.391 Å. The metacyclophane rings have a distance of 3.57 Å between their centres and form a dihedral angle of 20.5°. The phenyl substituent forms an angle of 78.6° with the adjacent ring and has an ortho H-atom very close to the internal H-atom of the opposite ring. The phenyl substituted aromatic ring is non-planar and in a shallow boat form, the ring atoms C(11) (internal) and C(14) being 0.038(4) and 0.037(5) Å out-of-plane on the outside, the methylene C substituents are 0.212(5) and 0.199(5) Å out-of-plane on the inside. The first atom of the phenyl group is in the bowsprit position and is 0.274(4) Å above the mean plane on the outer side of the molecule. The opposite metacyclophane ring is less strained but in a similar boat form with the methylene C-atoms 0.092(4) and 0.067(6) Å to the inside. The mean bond angle at S is 103.5(2)°, the angles at C (methylene) range from 113.3(3)° to 118.0(3)°.The variable temperature 1 Hmr spectra results are consistent with the syn conformer 6 being dominant in solution and frozen at temperatures <60 °C as conformer A, with only relatively restricted further twisting of the biphenyl being found at ambient temperature.