STRUCTURES OF HYDRATED TITANIUM AND VANADIUM IONS IN AQUEOUS-SOLUTIONS STUDIED BY X-RAY ABSORPTION-SPECTROSCOPY

The structures of titanium(III) and (IV), as well as vanadium(II), (III), and (IV) ions in aqueous solutions were investigated by the use of EXAFS (Extended X-ray Absorption Fine Structure) and XANES (X-ray Absorption Near Edge Structure). The TiIV ion in a sulfuric acid solution was found to form a-TiIV-O-TiIV-chain structure which is known to be present in the TiOSO4·2H2O crystal. The XANES spectrum of a mixed-valence complex, TiIII-IV, in solution agrees with the sum of the individual XANES spectra of TiIII and TiIV, indicating a retention of individual oxidation states and coordination structures. While the peaks pertaining to Ti-Ti and V-V interactions were observed in the EXAFS Fourier transform spectra for TiIV in a sulfuric acid solution and for VIII in a hydrochloric acid solution, the mixed-valence complex, TiIII-IV, did not show the Ti-Ti peak. © 1990 The Chemical Socity of Japan.