Electrochemical and Spectroscopic Studies of Some Tungstocuprate Heteropolyanions in Polar and Nonpolar Solvents. Reaction with Superoxide

摘要

This thesis describes some of the chemistry of copper(II) heteropolyoxotungstate anions viewed as inorganic analogues of copper porphyrins. The heteropolytungstate anions, XW11O39Cu(II)-OH2n-(X = Si, B, Zn) were synthesized and isolated as the potassium salts. Electrochemical investigation of these anions at pH 2.2, 4.7, and 6.0 revealed no evidence of oxidation to Cu(III) derivatives. Organic solutions of the Si heteropolyanion were generated by extracting the aqueous potassium salt into benzene and toluene using tetraheptylammonium bromide. The (Bu4N)4H2SiW11O39Cu (I) salt (soluble in acetonitrile) was isolated and characterized by analysis, potentiometric titration and ESR spectroscopy. In the polar and nonpolar non-acqueous solvents, the water molecule coordinated to the Cu is lost, as shown by changes in ESR and optical spectra. Cyclic voltammograms of I and its deprotonated form (II) in acetonitrile showed no copper oxidation feature. Treatment of solutions of II in toluene or acetonitrile with Br2 or O2 at ambient and low temperatures did not result in oxidation or oxygenation of the heteropolyanion. Corresponding treatment with superoxide anion, O2-, led to new ESR-active products.