Two-dimensional rhombus grid coordination polymer showing heterogeneous catalytic activities

A coordination polymer, {[Cd(L)2(DMF)2]·(ClO4)2·(2DMF)}n (1) (L = bis-(4-imidazol-1-yl-phenyl)-diazene) has been synthesized at room temperature. The polymer forms a two-dimensional (2D) rhombus-grid sheet structure. These 2D sheets are stacked in ABAB… mode with an inter-planar spacing of 3.729 Å. Each Cd(II) ion is equatorially bonded to four imidazole N atoms belong to four different ligand units while O atoms from two DMF molecules occupy the axial sites. Two ClO4− counter anions as well as two DMF molecules occupy the void space in each rhombus grid. This compound catalyzes cyanosilylation reactions of aromatic aldehydes in dichloromethane under mild conditions in heterogeneous fashion. On heating 1 at 120 °C for 4 h, all DMF molecules are lost and the ClO4− anions move out of the void space to occupy the axial sites on the metal to yield, de-solvated {[Cd(L)2(ClO4)2]}n (1) without losing crystallinity. De-solvated 1 exhibits heterogeneous catalytic activity in several Knoevenagel condensation reactions at RT.

A two dimensional coordination polymer has been synthesized at room temperature which acts as a heterogeneous catalyst for cyanosilylation of aromatic aldehydes. On heating, all the solvent molecules escape from the framework and the resulting polymer catalyzes the Knoevenagel condensation reaction under milder conditions.Figure optionsDownload high-quality image (120 K)Download as PowerPoint slideHighlights
► Cd(II) based coordination polymer as heterogeneous catalyst.
► As-synthesized polymer acts as a Weak Lewis acidic catalyst.
► After activation the resulting polymer exhibits weak Lewis basic catalytic activity.
► All catalytic reactions are heterogeneous in nature.