1-D Structures of assemblies containing oxamidato dicopper building blocks controlled by ditopic N-donor spacers

The assembly of the ditopic N-donor ligands bpy, bpe or dapm and the building block [Cu(trans-oxpy)Cu](2+) (H(2)oxpy=N,N'-bis(2-pyridylmethyl)oxamide) gave rise to three 1-D coordination polymers [Cu-2(trans-oxpy)(bpy)(H2O)(2)](n)[NO3](2n). nH(2)O (bpy=4,4'-bipyridine) 1, [Cu-2(trans-oxpy)(bpe)(H2O)(2)](n)[NO3](2n). 3nH(2)O (bpe=1,2-di-4-pyridylethylene) 2 and [Cu-2(trans-oxpy)(dapm)(2)](n)[NO3](2n). 6nH(2)O (dapm=4,4'-diaminodiphenylmethane) 3 and their structures were determined by single crystal X-ray crystallography. The copper atoms, which are located in distorted square-based pyramidal environments in all the complexes, are bridged alternately by oxpy and a ditopic spacer ligand to form infinite chains with fine structures varying with the flexibility of the ligand. Furthermore, there are interchain pi...pi interactions in 1 and 2 between the pyridyl rings of oxpy and the spacers. The dinuclear unit [Cu(trans-oxpy)Cu](2+) displays an integrity in the assembly process. Variable temperature magnetic susceptibility measurements on 3 showed the presence of antiferromagnetic coupling interactions between the copper(II) ions bridged by oxpy. Thermal analyses indicated that dehydration occurred around 110 degreesC and these complexes are stable up to 230 degreesC.