Azido bridged two new ferromagnetic Cu(II) chains: synthesis, structure and magnetic behaviour

Two new polynuclear copper(II) complexes, derived from the end-to-end azido bridging ligand and two tridentate (NNN-donor) Schiff base ligands have been synthesised and their single crystal structures have been determined. They are single azido bridged chains, [Cu(L1)(μ-1,3-N3)]n(ClO4)n (1) and [Cu(L2)(μ-1,3-N3)]n(ClO4)n (2) where L1 and L2 are two different tridentate Schiff bases obtained from the condensation of pyridine-2-aldehyde with N, N, 2, 2-tetramethylpropane-1, 3-diamine and 1-dimethylamino-2-propylamine, respectively. Structural analyses reveal that each copper(II) centre in both the complexes are in square pyramidal geometry. The azido ligand is bridged in such a fashion that one of the nitrogens of the bridging azide is linked to equatorial of one copper(II) while the other in the axial of the neighbouring copper(II). Low temperature magnetic susceptibility data show weak intrachain ferromagnetic interaction through end-to-end azido pathway in both the complexes. The magnetic data are fitted to a high temperature series expansion for 1D system with S=1/2 local spin based on the Hamiltonian H=−JΣSiSi+1, giving the parameters J=2.69 cm−1, g=2.10 for (1) and J=2.02 cm−1, g=2.02 for (2).