X-ray powder and single crystal structures of two unprecedented families of bpca-based 1-D magnetic chains (Hbpca = bis(2-pyridylcarbonyl)amine)

Two unprecedented families of bpca-based mono-dimensional complexes Cu(bpca)(X) (X = CN, 1; N3, 2) and [Cu1 − xFex(bpca)](ClO4) (x = 0, 3; 0.23, 4) were synthesised. The structure of 1 was solved ab initio from X-ray powder diffraction data and refined by Rietveld methods. The complexes 3–4 were characterised by X-ray single crystal diffraction. In 1 the cyano ligand coordinates the metal centres, the Cu centres forming a zigzag 1-D chain along the (0 0 1) direction, while in 3–4, the bpca ligand itself acts as the link towards the metal ions which are arranged in a linear 1-D chain running parallel to the (0 0 1) direction. An infrared spectroscopy study confirmed these coordination modes. The magnetic properties of both chain families were studied. 1–2 do not show significant magnetic interactions, whereas the magnetic behaviour for 3–4 suggests dominant antiferromagnetic interactions between the metal ions within the chains. The magnetic behaviour of 3 was analysed using the Padé approximation of the Bonner–Fisher model for S = 1/2 antiferromagnetic chains. The J value was estimated as 10 K.