New discrete and polymeric supramolecular architectures derived from dinuclear (bis-β-diketonato) copper(II) metallocycles

New examples of adducts between di- (and, in one instance, tetra-) functional nitrogen ligands and planar 'platform-like' dinuclear copper(II) complexes, [ Cu2L2], incorporating the 1,3- aryl linked bis- beta- diketonato bridging ligand 1,1'-(1,3- phenylene)- bis(4,4- dimethylpentane- 1,3- dione) (H2L) have been synthesised. The X- ray structures of six adduct species are reported. The interaction of [ Cu-2(L)(2)] with the ditopic ligand aminopyrazine (apyz) yielded the sandwich- like tetranuclear species [(Cu2L2(apyz))(2)]. A variable- temperature magnetochemical investigation of this product indicated weak antiferromagnetic coupling between the (five- coordinate) copper centres, mediated by the 2- aminopyrazine linkers. An analogous structure, [(Cu2L2(dabco))(2)] (dabco = 1,4- diazabicyclo[2.2.2] octane), was generated when dabco was substituted for aminopyrazine while use of 4,4'- dipyridyl sulfide (dps) and 4,4'-(1,3- xylylene)- bis(3,5- dimethylpyrazole) (xbp) as the ditopic 'spacer' ligands resulted in polymeric species of type [Cu2L2(dps)](n) and [Cu2L2(xbp)](n), respectively. These latter species exist as one- dimensional chain structures in which copper(II) centres on different dinuclear platforms are linked in a 'zigzag' fashion. In contrast, with 2,2'-dipyridylamine (dpa) a discrete complex of type [ Cu2L2(dpa) 2] formed in which one potential pyridyl donor from each 2,2'-dipyridylamine ligand remains uncoordinated. The use of the potentially quadruply- bridging hexamethylenetetramine (hmt) ligand as the linker unit was found to give rise to an unusual two- dimensional polymeric motif of type [(Cu-2(L-2)(2))(3)(hmt)(2)](n). The product takes the form of a (6,3) network, incorporating triply bridging hexamethylenetetramine units.