In the 1 : 2 host-guest complex formed between 1,4,7,10,13,16-hexaoxacyclo-octadecane (18-crown-6) and benzenesulphonamide, the crown ether adopts nearly the same conformation as the uncomplexed hexaether ; the complex is held together mainly by N-H ---0 hydrogen bonds.THE ability of crown ethers to form host-guest complexes with alkaline earth metal cations and ammonium salts is well known. Preliminary X-ray crystallographic results of Dunitz et aZ.3 shows that 18-crown-6 exists in different W . Germany) conformations in free and complexed forms. X-Ray crystal structure determinations of complexes of crown ethers with CH-4 and OH-acid5 substrates show that the crown ether in these compounds adopts a conformation with D,,-symmetry which is typical of potassium complexes.We report the solid-state structure of the product of reaction of 18-crown-6 with the NH-acid substrate, benzenesulphonamide, which can be obtained by a method similar to that used earlier for other compounds.6 Crystals of the complex are obtained as colourless needles, m.p. 365 K, which gave satisfactory microanalytical data.

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Verfasser zeigen an den Beispielen (I)‐(IV), daß sich Schwermetallkomplexe makrocyclischer Polyäther am besten in einer Umkehrung der klassischen Methode durch eine F ällungsreaktion darstellen lassen.

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