Relation between structure and catalytic properties of transition metal complexes with heteropolyanion PW11O397- in oxidative reactions

The content and structural features of transition metals Fe(III), Cr(III), Ru(IV), Ti(IV) and V(IV) complexes with the heteropolyanion PW11O397- depending on the starting M-compound, molar ratio of reagents, temperature and pH of the solution were studied. Heteropolycomplexes (HPC) of three types were identified using NMR (31)p, O-17 W-183, IR, UV-VIS spectroscopy, magnetic measurements and elemental analysis: I - M-substituted HPC, II - M-supported HPC, III - polynuclear hydroxocomplexes of M, stabilized by the heteropolyanion. The catalytic properties of HPC obtained have been studied in oxidation of cyclohexene, benzene, alcohols, aldehydes with hydrogen peroxide and other oxygen containing oxidants. It was demonstrated, that the nature of bonding of metal ions with the heteropolyanion, additional ligands of M ions in HPC content, as well as the composition of reaction mixture are the governing factors of HPC catalytic performance. A mechanistic study of hydrogen peroxide participated oxidations in the presence of Cr(III)- and Fe(III)-containing HPC was performed.