Synthesis and Characterization of 6-Ti-Substituted Polyoxomolybdate with High Catalytic Activity for Sulfide Oxidation.

A 6-Ti-substituted polyoxometalate, (NH 4 ) 5 Cs 7 Na 3 H 2 [Cs@(Ti 2 GeMo 10 O 39 ) 3 ]·34H 2 O ( 1 ), was synthesized by reacting (NH 4 ) 6 Mo 7 O 24 ·4H 2 O, GeO 2 , and TiOSO 4 through the conventional aqueous method. Polyanion 1a is composed of three {Ti 2 GeMo 10 } segments linked by Ti-O-Ti linkages and shows a trefoil-shaped structure. Furthermore, one Cs + cation is encapsulated in the cavity of 1a . Notably, it possesses the highest number of Ti centers among the reported polyoxomolybdates. In addition, serving as a high-efficiency heterogeneous catalyst, 1 enables the conversion of methyl phenyl sulfide within 20 min, yielding 96.4% of the corresponding sulfoxide with good recyclability.