SYNTHESIS AND SPECTRAL PROPERTIES OF TITANIUM(IV) POLYNUCLEAR HYDROXOCOMPLEXES STABILIZED IN SOLUTION BY THE [PW11O39](7-) HETEROPOLYANION

Unsaturated heteropolyanions (HPA) [PW11O39](7-) stabilize Ti-IV hydro xo complexes in aqueous solutions (Ti : PW11 [PW11O39](7-) less than o r equal to 12, pH 1-3). Spectral studies (optical, O-17 and P-31 NMR, and IR spectral and studies by the differential dissolution method dem onstrated that Ti-IV hydroxo complexes are stabilized through interact ions of polynuclear Ti-IV hydroxo cations with heteropolyanions [PW11T iO40](5-) formed. Depending on the reaction conditions, hydroxo cation s Tin-1OxHym+ either add to oxygen atoms of the W-O-Ti bridges of the heteropolyanions to form the complexes [PW11TiO40 . Tin-1OxHy](k-) (at [HPA] approximate to 0.01 mol L-1) or interact with Ti-IV of the hete ropolyanions through the terminal O atom to give the polynuclear compl exes [PW11O39Ti-O-Tin-1OxHy](q-) (at [HPA] approximate to 0.2 mol L-1) . When the complexes of the first type were treated with H2O2, Ti-IV i ons added peroxo groups.