. Can. J. Chem. 57, 3080 (1979).The crystal structure of syn-2,l I-dithia[3,3]metacyclophane, C16H16S2, has been determined by single crystal X-ray diffraction and refined to an R-value of 0.049. The crystal is monoclinic with cell dimensions a = 1898.2(5), b = 795.7(3), c = 924.1(4) pm, p = 100.03"(4). The 'Hmr data have been re-examined and compared with those obtained for other cyclophanes, together with 13Cmr data and are consistent with the fact that in solution 2,ll-dithia[3,3]metacyclophane, 1, exists as the syn-conformer with no appreciable participation of the anriconformer. All related dithia[3,3]metacyciophanes which have internal aryl hydrogens (i.e., no internal substituents) likewise appear to be syn from 'Wmr data.

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. Can. J. Chem. 62, 661 (1984).The crystal structure of syn-9-phenyl-2,11-dithia[3,3]metacyclophane, 6, has been determined by single crystal X-ray diffraction an{ 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) A, a = 108.02(2)", P = 95.95(2)", y = 102.25(3)", and the space group is PI with two molecules per cell, D,,,,,, = 1.3 13 g cm-', D,,,,,, = 1.306 g cm-'. The bridging S atoms differ in their conformations so that the S . . . S distance is 6.391 A. The metacyclophane rings have a distance of 3.57 A 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(l I) (internal) and C(14) being 0.038(4) and 0.037(5) A out-of-plane on the outside, the methylene C substituents are 0.212(5) and 0.199(5) A out-of-plane on the inside. The first atom of the phenyl group is in the bowsprit position and is 0.274(4) A above the mean plane on the outer side of the molecule. Tht opposite metacyclophane ring is less strained but in a similar boat form with the methylene C-atoms 0.092(4) and 0.067(6) A 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 '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.WILLEM ANKER, KATHY A. BEVERIDGE, GORDON W. BUSHNELL et REGINALD H. MITCHELL. Can. J. Chem. 62,661 (1984). On a dtterminC la structure cristalline du phCnyl-9 dithia-2,ll [3,3]mCtacyclophane-sy, 6, par diffraction de rayons-X sur un cristal unique et on I'affinCe jusqu'a une valeur de R de 0,0723. La structure cristalline est triclinique avec a = 9,573(2), Les spectres de rmn du proton a tempkrature variable sont en accord avec l'hypothkse que la conformation syn (6) est prepondkrante en solution et qu'a des tempkratures <6OoC, le produit est fig6 sous la conformation A alors que l'on ne peut observer que des variations relativement faibles du biphCnyle a la temperature ambiante.[Traduit par le journa)]