Twelve new compounds α 2 -M a H b [P 2 W 18 Ϫ n Ti n O 62 ]ؒxH 2 O and α-1,2,3-M a H b [P 2 W 18 Ϫ n (TiO 2 ) n O 62 Ϫ n ]ؒxH 2 O (M = K ϩ , NEt 4 ϩ or NBu 4 ϩ ; n = 1, a ϩ b = 8; n = 3, a ϩ b = 12) were synthesized from vacant heteropolytungstate precursors α 2 -[P 2 W 17 O 61 ] 10Ϫ and α-1,2,3-[P 2 W 15 O 56 ] 12Ϫ . The products were characterized by IR, UV spectroscopy, polarography, cyclic voltammetry and X-ray photoelectron spectroscopy. Tungsten-183 NMR studies showed that the titanium atoms or the peroxotitanium group in the anions are at 'polar' sites. The polarographic results indicated that there was a polarographic reduction potential of O 2 2Ϫ at ca. Ϫ0.08 V and that of Ti 4ϩ at ca. Ϫ0.20 V. The characteristic charge-transfer absorption band O 2 2Ϫ→Ti at 318 nm occurs in the UV spectra. The peroxotitanium (TiO 2 ) groups show two additional characteristic bands at ca. 870 and ca. 490 cm Ϫ1 in the IR spectra.

No abstract