A New Anion Exchanger Containing Cobalticinium Cation

Abstract

Abstract A New type of anion-exchanger, polymeric olygomethylene cobalticinium cation, was synthesized and its ion-exchange properties and stability toward heat and reagents were investigated in comparison with those of the ion-exchange resins. The preparative method of the exchanger was the same as that for polymeric olygomethylene ferrocene; hexamminecobalt(II) chloride was added to the product of α, ω-dicyclopentadienyl alkane with sodium. Although the pure products could not be obtained, the substance extracted with water showed several peaks common to a cobalticinium cation in IR spectra. The content of cobalt in tetraphenyl borate was 0.175 mmol/g, which corresponded to 91% trimethylene cobalticinium tetraphenyl borate. The saturated ion-exchange capacity of the eschanger was 1.75 meq/g, which was half the theoretical value. This discrepancy could be attributed to the shortage of cobalt according to the results of chemical analysis and magnetic susceptibility measurements. Although ionexchange resins lose their exchange capacity by heating at 150°C in air, this exchanger was thermostable decreasing to only 70% in ion-exchange capacity. The ion-exchange capacity of the exchanger in hydrothermal water at 220°C decreased to 55–35%, while that of resins drops to as low as 20%. The selectivity coefficient for various anions became smaller in the order; ClO4−>I−>ClO3−>BrO3−>Br−>Cl−>IO3−>F−. This tendency was the same as that for ion-exchange resins.