engleski

Novel complexes of copper(II) with tridentate hydrazone ligands

New complexes with different structures and properties were obtained by the reaction of tetrakis(μ acetato)diaquadicopper(II) with appropriate hydrazone ligand. Hydrazones represent the most common type of tridentate ONO donors. They are stabilized by ketamine- enolimine tautomerization. Hydrazone ligands H2L(1), H2L(2) and H2L(3), used in this investigation, were prepared by condenzation of benzohydrazide with different aldehydes: salicylaldehyde (R1 = H, R2 = H), 3- metoxysalcylaldehide (R1 = -OCH3, R2 = H), 4- metoxysalcylaldehide (R1 = -H, R3 = -OCH3, )respectively. Reactions of tetrakis(μ- acetato)diaquadicopper(II) with H2L(1), H2L(2) and H2L(3)in methanol resulted in formation of polymers of the general fomula [Cu(L)]n while in the case of reaction with H2L(2) a cuban type tetranuclearcluster [Cu(L)]4 is also obtained. Addition of pyridine to the reaction mixtures of [Cu(OAc)2(H2O)]2 and H2L(1), H2L(2) and H2L(3) resulted in formation of dimeric complexes [Cu(L) (py)]2 with pyridine molecules coordinated to copper atoms. Mononuclear complex [Cu(L3)(D)] was isolated when in reaction mixture 1, 10-phenantroline was added. These complexes are unstable and upon standing at room temperature lose pyridine molecules yielding [Cu(L)]2. After exposure of [Cu(L)]2 to pyridine vapours, it is possible to recover the starting complex. This is accompained with colour change from pale green to original dark green. Preliminary magnetochemical measurements of prepared dinuclear and tetranuclear complexes indicate antiferromagnetic arrangement of spins at low temperatures. All isolated complexes were identified by elemental and thermogravimetric analysis, IR spectroscopy and powder X-ray diffraction method. In case of [Cu(L)(py)]2(L=L(1), L(2) or L(3))[Cu(L2)]4 and [Cu(L3)(D)], syngle crystal diffraction was additionaly used.

hydrazones ; dimeric complexes ; cuban type clusters

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