The largest Se-4f cluster incorporated polyoxometalate with high Lewis acid–base catalytic activity.

A 4p–4f cluster incorporated polyoxometalate (POM), namely, H₁₈{[(H₄pic)₄Eu₁₀Se₁₃O₂₈(H₂O)₁₂](α-GeW₉O₃₄)₄·40H₂O (1-Eu, H₄pic = isonicotinic acid), has been first synthesized and characterized. 1-Eu features an interesting four-shell structure, representing the largest Se-4f cluster incorporated POM known to date. Besides, 1-Eu exhibits excellent Lewis acid–base catalytic activity and reusablity in catalyzing the gram-scale dehydration condensation reaction of hydrazines and 1,3-diketones to synthesize polysubstituted pyrazoles. [ABSTRACT FROM AUTHOR]