Organophosphonate-Functionalized Telluromolybdate Containing a [TeMo10O37]10- Building Block and Its Catalytic Efficiency for Knoevenagel Condensation.

A novel organodiphosphonate-based telluromolybdate cluster, (NH4)6Na3H13[TeMo10O37(CoMo2O6L)4]·11H2O [1; L = (O3P)2C(O)(CH2)3NH2], has been successfully synthesized by a simple one-pot aqueous reaction. Intriguingly, the [TeMo10O37]10- subunit with tetrahedral geometry of TeO4 is observed in the organophosphonate-functionalized polyoxometalates for the first time. Compound 1 was prepared in a buffer solution (pH = 5.5) with alendronic acid (Ale) and (NH4)6Mo7O24·4H2O as raw materials. The polyanion [TeMo10O37(CoMo2O6L)4]22- was constructed from four {Mo2O6L} subunits encapsulating an interesting Te-Mo heterometal subunit [TeMo10O37]10- through four CoO6 octahedra and has been fully characterized by routine techniques. In addition, compound 1, as a heterogeneous catalyst, shows good conversion (92%) and high selectivity (99%) for Knoevenagel condensation reaction.