Azacrown ether–copper(ii)–hexanoate complexes. From monomer to 1-D metal organic polymer

Abstract

The synthesis and characterisation of two new Cu(II)-hexanoate-azacrown ether species are described. The first monomeric complex is a “classical” macrocyclic Cu(II) complex with two monodentate axially coordinated carboxylates serving as counterions. The second is an adduct of the former complex with the copper(II) hexanoate paddlewheel dimer, Cu₂(hexanoate)₄, forming an infinite 1-D chain of alternating monomer–dimer units. The electronic and magnetic properties of both species are discussed based on UV-vis, IR, X-ray and EPR studies combined with the DFT calculations. The UV-vis titration results prove that complex 1 and the polymeric species 2 are in equilibrium in toluene solution.