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

Abstract

The assembly of the ditopic N-donor ligands bpy, bpe or dapm and the building block [Cu(trans-oxpy)Cu]²⁺ (H₂oxpy = N,N′-bis(2-pyridylmethyl)oxamide) gave rise to three 1-D coordination polymers [Cu₂(trans-oxpy)(bpy)(H₂O)₂]_n[NO₃]_2n·nH₂O (bpy = 4,4′-bipyridine) 1, [Cu₂(trans-oxpy)(bpe)(H₂O)₂]_n[NO₃]_2n·3nH₂O (bpe = 1,2-di-4-pyridylethylene) 2 and [Cu₂(trans-oxpy)(dapm)₂]_n[NO₃]_2n·6nH₂O (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 π ⋯ π 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 °C and these complexes are stable up to 230 °C.