Structural analysis and magnetic properties of the dicubane-like tetramer [Ni(dpk·OH)(N3)]4·2H2O (dpk = di-2-pyridyl ketone)

Abstract

A nickel(II)tetramer with azide and di-2-pyridyl ketone (dpk) of general formula [Ni(dpk·OH)(N₃)]₄·2H₂O (dpk·OH being the deprotonated gem-diol resulting from hydrolysis of dpk) was synthesized and structurally characterised through X-ray single crystal diffraction analysis and IR spectroscopy. The structure consists of dicubane-like tetrameric entities where simultaneous (1,1)-N₃ and O bridges can be found, being an unprecedented arrangement for metal(II) azide systems. Measurements of the magnetic susceptibility revealed the occurrence of ferromagnetic interactions in the clusters. The extension of the magnetic exchange has been evaluated by means of a spin Hamiltonian with four J constants (J₁ = 18.8, J₂ = 6.9, J₃ = 1.3 and J₄ = 0.2 cm⁻¹).