Ligand-Directed Approach in Polyoxometalate Synthesis: Formation of a New Divacant Lacunary Polyoxomolybdate [γ-PMo10O36]7.

Polyoxometalates (POMs) have received increasing attention over the last decades for extending their application and properties that originate from novel structures. For the synthesis of a variety of POM structures, multivacant lacunary POMs are key precursors, which are typically synthesized by empirically controlling the complex equilibrium in aqueous solvents. Unfortunately, despite the excellent catalytic and electrochemical properties of "polyoxomolybdates", only one multivacant lacunary species, i.e., [A-α-PMo9 O34 ]9- , has been identified and isolated because multivacant lacunary polyoxomolybdates are typically unstable. Here we report a ligand-directed approach for the selective formation of an unprecedented lacunary polyoxomolybdate in organic solvents. By structure transformation of a pyridine-coordinated [A-α-PMo9 O34 ]9- , a new γ-Keggin-type divacant lacunary polyoxomolybdate [γ-PMo10 O36 ]7- was obtained, which can be further used as a precursor for synthesizing a POM-organic hybrid.