Crystal structure of 7,15,17,19-tetraethoxy-2,3,4,5,10,11,12,13-octathiatricyclo[12,2,2,26, 9]eicosa-6,8,14,16,17,19-hexaene, a sulphur analogue of the paracyclophanes

Abstract

The crystal and molecular structure of the title compound has been determined from three-dimensional X-ray diffractometer data. The material crystallizes in space group P2₁/c with Z= 4 in a unit cell of dimensions a= 10·198(5), b= 9·454(5), c= 29·845(16)Å, β= 115·17(8)°. The final R was 0·043 for 2590 unique reflections. The molecule is tricyclic, with two phenyl rings and a sixteen-membered ring of composition C₈S₈. The phenyl groups are planar and nearly parallel to one another (the angle between the normals to the planes of the two phenyl rings is 1·7° and the bond lengths and angles in the (EtO)₂C₆H₂ fragments of the molecule are normal. Because of their ortho-positioning in the phenyl rings, there are relatively short oxygen–sulphur contacts which are made more pronounced by a bending of the oxygen and sulphur atoms towards each other (mean internal C–C–S and C–C–O angles 116·2 and 115·3°). The length of the sulphur–carbon bonds indicate the presence of double-bond character and there is an alternation of bond lengths in both independent S₄ chains, which suggest conjugation between phenyl rings across these chains.