Stereochemistry of anticholinergic agents. Part VI. Crystal and molecular structure of hexasonium iodide

Abstract

Hexasonium iodide {2-[cyclohexyl(phenyl)acetoxy]ethyldimethylsulphonium iodide} crystallises in the monoclinic space group P2₁/c with a= 16·04(2), b= 11·36(1), c= 11·12(1)Å, β= 92·58(5)°, and Z= 4. The structure was established by the heavy-atom method from three-dimensional X-ray counter data and refined by least-squares to R 6·3% for 2443 observed structure amplitudes. The cyclohexyl ring is in the chair conformation with the acetoxy-group in the equatorial orientation. In the C(:O)·O·C·C·S⁺ chain the C(:O)·O·C·C grouping is (–)-synclinal and the O·C·C·S⁺ grouping (+)-synclinal. The cyclohexyl and phenyl rings are oriented (+)- and (–)-anticlinal with respect to the ester oxygen atom. The overall shape of the cation resembles in some respects that of atropine and also that of a number of potent synthetic anticholinergic agents related structurally to acetylcholine. Mean σ for bond lengths, bond angles and torsion angles: 0·018 Å, 1·0, and 1·5°.