A Multivariate 2D Metal–Organic Framework with Open Metal Sites for Catalytic CO2 Cycloaddition and Cyanosilylation Reactions

This work reports the synthesis of a dual functional 2D framework, Zn2 (4-tpom) 2 (oxdz) 2·4H2On (1), at room temperature, where a bent dicarboxylate, oxdz2– (4, 4′- (1, 3, 4-oxadiazole-2, 5-diyl) dibenzoate), and a neutral flexible N-donor linker, 4-tpom (tetrakis (4-pyridyloxymethylene) methane), are utilized. Its single-crystal X-ray analysis indicated a 2-fold interpenetrated 2D framework having tetracoordinated Zn (II) centers and dangling pyridyl groups. Its further characterization was carried out with elemental microanalysis, FTIR spectroscopy, TG analysis, and powder X-ray diffraction. The tetracoordinated Zn (II) centers as active Lewis acidic sites and the N atoms of 4-tpom as Lewis basic sites in 1 are explored for its functioning as a heterogeneous catalyst in two important reactions, (i) cycloaddition of CO2 with various epoxides and (ii) cyanosilylation reaction under solvent-free conditions. We could successfully show the cycloaddition of styrene oxide with CO2 (99% conversion) under balloon pressure with low catalyst (0. 2–0. 3 mol %) and cocatalyst (0. 5–0. 75 mol %) loadings, which is otherwise difficult to achieve. It was observed that all the substrates (aromatic and aliphatic), irrespective of their sizes, showed conversion percentage >99%. In the cyanosilylation reaction, a conversion of 96% was obtained with 1. 5 mol % of 1 at room temperature for 12 h. This framework emerged as an excellent recyclable catalyst for both the reactions.