Formation, Reactivity, and Catalytic Behavior of a Keggin Polyoxometalate/Bipyridine Hybrid in the Epoxidation of Cyclooctene with HO.

The present study further explores the behavior of polyoxometalate-based hybrid compounds as catalysts for liquid-phase cyclooctene epoxidation with HO. Precisely, it unveils the nature of the relevant active species derived from the hybrid based on Keggin polyoxometalate (POM) and bipyridines (bpy) of formula (2,2'-Hbpy)[PWO] (). Whereas (i) it is generally accepted that the catalytic oxidation of organic substrates by HO involving Keggin HPAs proceeds via an oxygen transfer route from a peroxo intermediate and (ii) the catalytically active peroxo species is commonly postulated to be the polyperoxotungstate {PO[W(O)(O)]} complex (PW), we show that the studied epoxidation reaction seems to be more sophisticated than commonly reported.

Hybrid Materials Based on Keggin Phosphotungstate and Bipyridine with Valuable Hydrophobic and Redox Properties.

A thorough investigation of two novel hybrid materials, namely, (2,2'-Hbpy)[PWO] and (4,4'-Hbpy)[PWO]·1.5HO built from Keggin phosphotungstic acid (PTA) and bipyridine, describes the impact of bipyridine isomers in their formation and physicochemical properties. The hybrids' formation was confirmed by powder X-ray diffraction, while infrared spectroscopy (IR) proved the polyoxometalate (POM) structural preservation.