SYNTHESES AND CRYSTAL-STRUCTURES OF 4 ALICYCLIC DIOLS WHICH CRYSTALLIZE IN DIFFERENT LATTICES INVOLVING HELICAL EXTENSIONS

In an exploration of the possibility of modifying the shape and size o f the helical canal host structure known to occur in crystals of sever al bi- and tri-cyclic diols, we report the syntheses and structures of four further diols: -thiatricyclo[3.3.1.1(3,7)]decane-syn-4,syn-8-dio l 5; -thiatricyclo[3.3.1.1(3,7]decane-syn-4,anti-8-diol 6; yltricyclo[ 4.3.1.1(3,8)]undecane-syn-2,anti-7-diol 7; and 2,8-dimethyltricyclo[5. 3.1.1(3 9)]dodecane-anti-2,anti-8-diol 8. All four comprise a class of diols with crystal structures involving hydrogen bonded helices, and all but 7 are resolved into conglomerates on crystallisation. Diols 5 and 6 form closely-related helical columns in space group P4, and P4(3 ) respectively, with only van der Waals attractions between adjacent c olumns. These structures also involve intramolecular S ... H-O hydroge n bonds giving five-membered cycles which persist in solution. Diol 7 crystallises in space group Pna2(1) with a three-dimensional hydrogen bonded structure involving recurved spirals with a 4-fold diol repeat. The final diol 8 crystallises in space group P3(1)21 as a further mem ber of the helical tubuland canal structural family, but with void spa ces insufficient for inclusion of guest molecules. The structures are discussed with respect to crystal engineering aspects of synthesis.