Supramolecular bimetallic systems constructed through π-π stacking and hydrogen bond interactions

Five new bimetallic compounds have been synthesized and crystallographically characterized: [{Cu(acac)(phen)}(2){Ni(CN)(4)}] center dot H2O (1), [{Cu(acac)(bipy)(2)[Ni(CN)(4)}] (2); [Cu(acac)(bipy)(H2O)](2) [Ni(CN)(4)] (3), [(Cu(acac)(Me(2)bipy)](2)[Ni(mnt)2] (4), [Cu(acac) (bipy)][Ni(mnt)(2)] (5) (Me(2)bipy = 4,4'-dimethyl-2,2'-bipyridine; runt = maleonitriledithiolate). The molecular structures of complexes 1 and 2 are similar: they consist of neutral [{Cu(acac)(BB)}(2){Ni(CN)4}] entities, which result by connecting two [Cu(acac)(BB)](+) ions through two trans-cyano groups from the bridging ligand, [Ni(CN)(4)](2-) (BB = 1,10-phenanthroline and, respectively, 2,2'-bipyridine). The intermolecular pi-pi stacking interactions established between the organic ligands attached to the copper ions lead to supramolecular chains. In the ionic compound 3, the [Ni(CN)41 anions and the [Cu(acac)(bipy) (H2O)](+) cations generate a 3D supramolecular architecture by convolution of hydrogen bonding with pi-pi stacking interactions. The crystal structure of compound 4, [(Cu(acac)(Me2bipy)12 [Ni(mnt)(2)], consists of cationic, [(Cu(acac)(Me(2)bipy)](+), and anionic species, [Ni(mnt)(2)](2-), which are connected through Cu center dot center dot center dot S interactions, resulting in supramolecular {CuNiCu} trimers. Crystal 5 is an ionic compound containing [Cu(acac)(bipy)](+) and [Ni(mnt)2](-) ions.