W-183 NMR AND X-RAY CRYSTALLOGRAPHIC STUDIES ON THE PEROXO COMPLEXES OF THE TI-SUBSTITUTED ALPHA-KEGGIN TYPED TUNGSTOPHOSPHATES

Peroxo complexes prepared by the reaction of titanoundecatungstophosphate (PTiW11O40(5-)) and dititanodecatungstophosphate (PTi2W10O40(7-)) with hydrogen peroxide are characterized by means of the W-183 NMR spectroscopy and the single crystal X-ray diffractometry. Electronic spectra and permanganate titration analyses indicated that one peroxo ligand attaches to the PTiW11O40(5-)) anion and two peroxo ligands attach to the PTi2W10O40(7-)) anion. W-183 NMR spectra showed that the C(s) symmetry of the PTiW11O40(5-)) anion and the C2 symmetry of the PTi2W10O40(7-)) anion are retained in the respective peroxo derivatives. Single crystal X-ray structures of the diisopropyl ammonium salt of PTiW11O40(5-)), the diisopropyl ammonium salt of PTiW11O39(O2)5- and the isopropyl ammonium salt of PTi2W10O38(O2)2(7-) indicated that the peroxo anions retain the alpha-Keggin structures of their parent anions. It was inferred that the peroxo ligands are substituted for the terminal oxygen atom at the TiO6 octahedra with the side-on format.