Nb–Ta, Nb–Mo and Nb–V oxides prepared from hybrid organic–inorganic precursors

New hybrid organic–inorganic materials based on group 5 elements and a well-defined polymeric matrix have been prepared and used as precursors for Nb–Ta and Nb–Mo mixed oxides. In this non-conventional but easily accessible route to multimetallic oxides, a copolymer of N,N-diallyl-N-hexylamine and maleic acid was synthesised and used as matrix to stabilise inorganic species generated in solution from (NH4)6Mo7O24·4H2O, NH4VO3, (gu)3[Nb(O2)4] and (gu)3[Ta(O2)4]. Solid-state studies indicate that the homogeneity of the blends can be kept up to about 0.5 mol NbV and TaV and 0.25 mol VV per mol of repeat units of the copolymer. The calcination conditions of these homogeneous hybrid precursors were optimised to produce Nb–Mo, Nb–Ta and Nb–V oxides. While the thermal treatment of the Nb–V hybrid blends led only to a mixture of different phases, the characterisation of the final phases by X-ray diffraction (XRD) proved the formation of pure Nb2Mo3O14 and showed that Nb–Ta oxides could be synthesised as single phases corresponding to a continuous series of solid solutions.