Structural analysis and magnetic properties of the dicubane-like tetramer [Ni(dpk center dot OH)(N-3)](4)center dot 2H(2)O (dpk = di-2-pyridyl ketone)

A nickel(II)tetramer with azide and di-2-pyridyl ketone (dpk) of general fo rmula [Ni(dpk . OH)(N-3)](4). 2H(2)O (dpk . OH being the deprotonated gem-d iol resulting from hydrolysis of dpk) was synthesized and structurally char acterised through X-ray single crystal diffraction analysis and IR spectros copy. The structure consists of dicubane-like tetrameric entities where sim ultaneous (1,1)-N-3 and O bridges can be found, being an unprecedented arra ngement for metal(II) azide systems. Measurements of the magnetic susceptib ility revealed the occurrence of ferromagnetic interactions in the clusters . The extension of the magnetic exchange has been evaluated by means of a s pin Hamiltonian with four J constants (J(1) = 18.8, J(2) = 6.9, J(3) = 1.3 and J(4) = 0.2 cm(-1)).