A Lacunary Polyoxovanadate Precursor and Transition-Metal-Sandwiched Derivatives for Catalytic Oxidation of Sulfides.

A SeO3 -centered lacunary Keggin-type heteropolyoxovanadate (hetero-POV) K6 H2 [SeV10 O28 (SeO3 )3 ]⋅14 H2 O (1) was isolated by one-pot reaction of KVO3 and SeO2 under acidic conditions. X-ray studies revealed that it comprised a single {VO5 }-capped trivacant B-α-type Keggin ion [SeV9 O33 (VO)]14- with its lacunary sites decorated by three {SeO3 } pyramids. Interestingly, this new basic hetero-POV building block was further used as a precursor to assemble with different transition-metal (TM) ions, yielding a series of TM-sandwiched POVs K6 H8 [(SeV10 O28 (SeO3 )3 )2 (M(H2 O)4 )]⋅24 H2 O (M2+ =Mn2+ (2), Co2+ (3), Zn2+ (4)). All four compounds were characterized by single-crystal X-ray structure analysis, IR, X-ray photoelectron spectroscopy (XPS), EPR, and 51 V NMR spectroscopy. Importantly, three TM-sandwiched derivatives exhibited effective catalytic activity for the heterogeneous oxidative desulfurization of sulfides at room temperature.