Cluster-Organic Framework Materials as Heterogeneous Catalysts for High Efficient Addition Reaction of Diethylzinc to Aromatic Aldehydes

To explore the catalytic activity of heterometallic cluster-organic frameworks, three 3d-3d heterometallic cluster-organic frameworks based on the cooperative assembly of tetrahedral Cu4I4 and metal-carboxylate clusters with potential open metal sites were synthesized and described in detail. The structure of 1 consists of tetrahedral [Cu4I4(INA)4]4– metalloligands (INA = isonicotinate) linking unusual Zn8(μ4-O)(COO)12(H2O)4 clusters into a (4,12)-connected network. Compound 2 features a 2-fold interpenetrating 4-connected bbf-type framework based on new [Cu4I4(INA)2(DBO)2]2– metalloligands (DBO = 1,4-diazabicyclo[2.2.2]octane) and paddle-wheel Zn2(COO)4 units. The 2-fold interpenetrating diamond-type framework 3 is constructed from tetrahedral [Cu4I4(INA)4]4– metalloligand and Mn2(COO)4(H2O)2(DMF) unit with potential open Mn centers. All three framework materials have notable catalytic activity on the diethylzinc addition to aromatic aldehydes, and the catalytic properties of compound 1 have been studied in detail. The results reveal that the heterogeneous catalysis of the diethylzinc addition to aromatic aldehydes by using cluster-organic framework as catalyst is determined by several experimental factors, such as temperature, reaction time, and the incorporation of electron-withdrawing groups in aromatic aldehydes.