Synthesis and characterization of V substituted Anderson-type telluro-molybdates and tungstates for catalytic oxidation of furan derivatives to formic and maleic acid

Transition-metal substitution in polyoxometalates (POMs) is a well-established concept in POM chemistry. However, so far there are no well-founded studies in literature that deal with the selective substitution of one or more framework/addenda elements in the Anderson-Evans structure. Therefore, a concept of synthesizing Anderson-Evans-type POMs where the addenda elements are replaced by various RedOx active transition-metals would be useful from a catalytic point of view to produce new structures for RedOx catalytic applications. An interesting RedOx-active element is vanadium in the oxidation state +V. In this study, we report an experimental procedure to synthesize different V(+V) substituted Anderson-Evans-type molybdo- and tungstotellurates. The new compounds were characterized in detail both in solid-state as well as in aqueous solution by using different spectroscopic and electrochemical methods like vibrational (FTIR-, Raman) as well as magnetic (51V NMR) and UV-Vis spectroscopy. Finally, the successfully synthesized Anderson-Evans structures were applied as homogeneous catalysts in aqueous solution for the selective catalytic oxidation of monofuran derivatives to short-chain carboxylic acids to investigate their potential as RedOx catalysts.