Silicon polypodands 5–7 are found to be powerful complexing agents of alkali metal salts in low polarity solvents and very efficient catalysts in anion-promoted reactions under solid–liquidPTCconditions. The catalytic activity is comparable with that of the cyclic polyether PHDB18C6 8.
Silicon podands (1-10) were synthesised and their complexation reaction of Na+ cations were studied by calorimetric and PM5 theoretical methods. Both methods provide evidence for formation of the respective complexes with Na+ cations of different stoichiometry. In most cases, only formation of the complexes of 1:1 stoichiometry has been observed. For compounds with longer oxaalkyl chains (9 and 10) the formation of 1:4 and 1:6 complexes has been found. The structures of the complexes are visualised and discussed. (C) 2004 Elsevier B.V. All rights reserved.