SYNTHESIS, STRUCTURE, AND COORDINATION PROPERTIES OF SILICON-BRIDGED MACROCYCLES

Macrocyclic compounds are obtained in one step by the reaction of carb o- and heterocyclic dianions with bis-electrophiles, such as Me(2)SiCl (2), Me(2)SnCl(2), or PhPCl(2). p-tert-Butylmethoxybenzene as starting material affords silacalix[4]arene 7. The most stable conformers of 7 are determined by force field calculations. A 1,3 alternate conformat ion in the crystal is revealed by X-ray structure analysis for the het erocyclic silacalix[4]arenes 3a and 3c, while 3b shows a partial cone conformation. The ability of the macrocycles to extract metal ions fro m the aqueous phase is investigated in competition experiments. The te sted macrocycles extract metal ions, however, with less affinity than crown ethers.