The condensation of 1,1′-bis(chlorocarbonyl)ferrocene and 1,1′-bis(chlorocarbonyl) ruthenocene with 4-aminobenzo-15-crown-5 gives the metallocene bis(crown ether) ligands 1,1′-bis[(2,3,5,6,8,9,11,12-octahydro-1,4,7,10,13-benzopentaoxacyclopentadecin-15-yl) amino]carbonylferrocene (4) and the ruthenocene analogue (5). 13C NMR titrations of 4 and 5 with Na+, K+ and Cs+ alkali metal salts lead to titration curves interpreted as suggesting 1:1 stoichiometry. The single-crystal X-ray structure of [4K]PF6· 4MeOH reveals an intramolecular sandwich complex with the potassium guest cation in the solid state. Competition fast atom bombardment (FAB) mass spectrometry selectivity experiments show 4 and 5 to exhibit exclusive K+ selective complexation over either Na+ or Cs+. © 1989.
