Two rhombic-shaped Ln4 clusters for efficiently catalyzing CO2 cycloaddition and knoevenagel condensation.

• Two new rhombic-shaped Ln 4 compounds have been synthesized and structurally characterized. • The Ln 4 compounds exhibit good catalytic performances for cycloaddition of CO 2 with epoxides. • The Ln 4 compounds also exhibit good catalytic performances for knoevenagel condensation under mild condition. Two Ln 4 clusters with the formula of [Ln 4 (acac) 4 (µ 3 OH) 2 (L) 6 ]·xCH 3 CN (Ln=Sm (1), Yb (2)) were synthesized through the reaction of Ln(acac) 3 ·2H 2 O (Hacac = acetylacetone) with the bidentate flexible ligand 5-benzylidene-1,5-dihydroquinolin-8-ol. X-ray diffraction studies indicate that clusters 1 and 2 are isostructural and processes a rhombic-shaped Ln 4 core. The coordination geometry of each Ln(III) ion is characterized as a distorted square antiprism. Notably, clusters 1 and 2 exhibit outstanding catalytic performance for the cycloaddition of CO 2 with epoxides and for Knoevenagel condensation under mild conditions. Two rhombic-shaped Ln 4 clusters exhibit good catalytic performances for cycloaddition of CO 2 with epoxides and Knoevenagel condensation under mild condition, simultaneously. [Display omitted] [ABSTRACT FROM AUTHOR]