Mononuclear and polynuclear complexes with a side-off compartmental Schiff base

The compartmental Schiff base H-2-L, obtained by [2 + 1] condensation of 3-methoxy-2-hydroxybenzaidehyde and 1,5-diamino-3-azapentane, and the related mono- and hetero-polynuclear copper(II), zinc(II) and lanthanum(III) complexes have been prepared and their physico-chemical properties studied by IR, NMR, SEM-EDS and X-ray single crystal diffractometry. In the mononuclear complexes [M(L)] center dot nS (M = Cu-II, Zn-II, S = H2O, MeOH), obtained in alcoholic solution by the reaction of the free ligand and the appropriate metal acetate hydrate or nitrate or by [2 + 1] condensation of the formyl- and polyamine-derivatives in the presence of the desired metal salt, [L](2-) coordinates to the metal ion in the diimine form as ascertained by the 1 H NMR spectra of the zinc(II) complex. The hetero-dinuclear complexes have been prepared by the reaction of the copper(H) or zinc(II) mononuclear complex with La(NO3)(3)center dot 6H(2)O in 1:1 molar ratio. The copper-lanthanum complex is not a true heterodinuclear complex, as it can be described as {[Cu-2(H2L)(2)](2)[La(NO3)(6)](NO3)}, while heterodinuclear complexation occurs in {[ZnLa(H-L')(NO3)(3)(S)](NO3)) (S = H2O or C2H5OH), where a ring contraction at one imine group takes place, with the formation of a five-membered heterocyclic imidazolidine ring. (C) 2007 Elsevier B.V. All rights reserved.