Silver co-ordination compounds with aliphatic nitriles containing aminonitrogen as H bond donor or additional metal binding site: formation of a ring, a chain, a polymeric sheet and a 3D polymeric channeled structure

Abstract

Three co-ordination polymers and a discrete 20-membered macrometallacycle were prepared by crystallization of silver salts with the conformationally flexible, polyfunctional ligands N-(2-cyanoethyl)glycine (ceg), 3,3′-iminodipropionitrile (idpn) and tris(2-cyanoethyl)amine (tca). Single-crystal X-ray analyses of [Ag₂(tca)₂](ClO₄)₂ (1), [Ag(idpn)]ClO₄ (2), [Ag(ceg)]CF₃SO₃ (3) and [Ag(ceg)]ClO₄·0.5H₂O (4) revealed a bimetallic macrocycle (1), a 2D sheet structure with 4.8² topology (2), a 3D network structure with rhomboid channels (3) and a 1D chain structure (4). The rhomboid channels in 3 are generated by 36-membered macrometallacyclic subunits consisting of four Ag atoms and four ceg ligands with ceg binding through the carboxylate group and the nitrile nitrogen. The amino nitrogen of ceg is protonated and serves as a hydrogen bond donor for the triflate anions that are incorporated into the macrocycles, thus stabilizing the channeled structure.