Abstract:
The solubilities in organic solvents of five diheteropoly tungstates of the Keggin structure were investigated. Potassium salts of water soluble anions, aquocobalto(
II)-ll-tungstosilicate, aquocobalto(II)-ll-tungstogermanate, aquocobalto(III)-ll-tungstoborate, aquocobalto( III)-ll-tungstogallate, and uocobalto(III)-lltungstozincate, were converted to salts which were soluble in organic solvents. Thi s was accompl ished by mixing the potassium salts with tetra-n-heptylammonium bromide in a cyclohexane-water mixture. The absorption spectra were determined in eight selected organic solvents -cyclohexane, toluene, carbon tetrachloride, chloroform, methylene chloride, isopropyl alcohol, tetrahydrofuran, and acetonitrile. Most of the UV spectra of tetra-n-heptylammonium heteropoly compounds in solution exhibited two peaks. The visible spectra exhibited multiple peaks, indicative of pseudooctahedral
cobalt(II) or cobalt(III) chromophores. The wavelength of maximum absorbance was noted to shift with change of solvent polarity. The absorptivity values of the five compounds were determined in each of the eight organic solvents for all absorption bands.
