Catalytic properties of a series of coordination networks: cyanosilylation of aldehydes catalyzed by Zn(ii)-4,4′-bpy-carboxylato complexes

Abstract

Three porous crystalline coordination polymers, i.e. the three-dimensional framework {[Zn₃(4,4′-bpy)_3.5(μ-O₂CH)₄(H₂O)₂](ClO₄)₂(H₂O)₂}_n (1), the one-dimensional three-leg ladder {[Zn₃(4,4′-bpy)₃(μ-O₂CCH₃)₄(H₂O)₂](PF₆)₂(H₂O)₂}_n (2), and the two-dimensional layered network {[Zn₃(4,4′-bpy)₄(μ-O₂CCH₂CH₃)₄](ClO₄)₂(4,4′-bpy)₂(H₂O)₄}_n (3), have been investigated. All networks exhibit voids that contain the counter-ions and guest molecules, namely water for compounds 1 and 2, and water/4,4′-bpy for compound 3. In addition, compounds 2 and 3 are further stabilized by hydrogen bonds and π–π stacking interactions to form intricate supramolecular frameworks. The removal and reintroduction of guest water molecules for compounds 2 and 3 have been explored for their dynamic structural transformation. Interestingly, all Zn(II) compounds are active heterogeneous catalysts for the high-yield cyanosilylation of acetaldehydes in dichloromethane.