Cation Exchange in Layered Copper(II) Coordination Polymers

The covalently linked anionic layers of a series of Cu-II 2,3-pyridinecarboxylate anions containing organic cations are characterized. Depending on the cations, mononuclear, dinuclear or polynuclear complexes are formed. The complex with adeninium cations is mononuclear, whereas the complexes bearing cations of 4-aminobenzylamine, 1,5-diaminopentane, and 5-aminoquinoline are dinuclear, and complexes bearing cations of isopropylamine, ethylenediamine, 1,8-diaminooctane, N,N,N,N-tetramethylethylenediamine, tris(2-aminoethyl)amine, 1,4-diazabicyclo[2.2.2]octane, imidazole, pyridine, 8-hydroxyquinoline, and cytidine are coordination polymers. All of the complexes other than the one bearing tris(2-aminoethyl)amine cations have lamellar structures. The polynuclear complex anion with tris(2-aminoethyl)amine trications exhibits an unusual -3 charge for the polynuclear anionic nodes. The 1H,9H-adeninium cationic dimers are stabilized in the interstices of mononuclear Cu-II quinolinate complex anions. The interlayer separations in the layered polymers varied from 8.5 to 15.9 angstrom and are guided by the cations. Biologically relevant cytidinium cations are trapped in the layers of polymeric anions. The complexes bearing organocations undergo exchange of the organic cations with alkali, alkaline earth, or transition metal ions or with smaller cations without disturbance of the polymeric inorganic layer. The exchange of the cytidinium cations by metal ions resulted in polymeric complexes in which the cationic organic layer is replaced by a layer of aquated metal cations. The thermochemical properties, electron paramagnetic resonance (EPR) spectroscopy, and solid-state conductance of the complexes are described.