A new 4-Ti-added polyoxometalate

A new inorganic-organic hybrid 4-Ti-added polyoxometalate: [H2N(CH3)(2)](2)Na3H5[{Ti(C2O4)(H2O)}(2){Ti(C2O4)}(2)(B-beta-SbW9O33)(2)]center dot 22H(2)O (1) has been successfully made and further characterized by infrared spectroscopy, thermogravimetric analysis, powder X-ray diffraction and single-crystal X-ray diffraction. The polyoxoanion of 1 exhibits a Krebs-type structure that is constructed from two [B-beta-SbW9O33](9-) fragments fused together by a belt of four additional Ti atoms decorated by oxalate ligands. Furthermore, 1 as a heterogeneous catalyst exhibits high activity for Knoevenagel condensation under mild reaction conditions.