Cyano-Bridged 2D Cu^II−Cr^III Coordination Polymers: Structural Evidence for Formation of a Polymeric Macrocyclic Metallic Compound

Two unique cyano-bridged 2D coordination polymers have been synthesized and characterized structurally and magnetically. The complexes contain two polyaza Cu(II) units and one novel macromolecular Cu(II) moiety, which have been synthesized via one-pot metal template condensation reactions involving ethylenediamine (en) and formaldehyde. Self-assembly of the polyaza CuII mixture with [Cr(CN)6]3- gave rise to two layered complexes. One complex contains unprecedented covalently linked polymeric CuII chains and cyano-bridged CuII-CrIII coordination chains, which are interwoven to form a novel layer. The other complex shows intriguing encapsulation of [Cr(CN)6]3- anions. Intermetallic ferromagnetic coupling is operative within the bridged 2D layer. The magnetic susceptibilities of both complexes were simulated using approximate models.