Crystal structure of two bridged macrobicyclic polyethers, 1,5,12,16,23,26,29-heptaoxa[7][5.5]orthocyclophane and 1,5,12,16,23,26,29,32-octaoxa[10][5.5]orthocyclophane

Abstract

The crystal structures of the two title compounds (1) and (2) have been solved by direct methods from diffractometer data. Both compounds crystallise in the rhombohedral space group R, and the obverse hexagonal cell was used in each case. The cell dimensions found were a= 33.569(11), c= 9.182(5)Å for compound (1) and a= 34.772(7), c= 9.743(2)Å for (2), and Z= 18. The structures have been refined to R= 0.040 for the 3 204 observations of (1), and R= 0.084 for the 1 621 observed planes in (2). The molecules have similar shapes and can be considered best as bridged analogues of the monocyclic crown ethers, benzo-15-crown-5 and benzo-18-crown-6, respectively. They each show an open face containing several oxygen atoms which would be available to complex with cations. The packing of the molecules in the crystals is very similar, in each case, one benzene ring being ‘stacked’ above that in a neighbouring molecule.