ALKALI-METAL BINDING-PROPERTIES OF SIMPLE FERROCENYL-SUBSTITUTED AND RUTHENOCENYL-SUBSTITUTED AZA-CROWN ETHERS

Reaction of 1-chlorocarbonyl-ferrocene or -ruthenocene with crown-5(1, 4,7,10-tetraoxa-13-aza-cyclopentadecane) afforded the respective amide -linked metallocene crowns. Nucleophilic displacement of trimethylamin e from trimethyl ammoniomethyl-ferrocene or -ruthenocene iodides with aza-15-crown-5 yielded the corresponding methylene-linked crowns. Vari able-temperature C-13 NMR investigation of the hindered rotation about the amide links of the amide-linked crowns in the presence of guest c ations indicated that cation complexation occurs exclusively within th e crown ring. Extraction experiments with a range of metal-cation dye salts revealed a favourable binding capacity for the methylene-linked crowns. Detailed C-13 NMR analysis of sodium and potassium ion binding by these systems suggests the presence of a stabilising interaction b etween the metallocene pi system and the crown-bound cation. Cyclic vo ltammetric analysis of metal-ion binding by the amine-linked crowns re vealed cation-induced shifts of the appropriate redox couple comparabl e with those reported for related systems.