FROM COMPOUNDS TO MATERIALS - HETERODINUCLEAR COMPLEXES AS PRECURSORS IN THE SYNTHESIS OF MIXED OXIDES - CRYSTAL-STRUCTURES OF [CU(H2LA)] AND [(CUY(LA)(NO3)(DMSO))2]2DMSO [H4LA = N,N'-ETHYLENEBIS(3-HYDROXYSALICYLIDENEIMINE), DMSO = DIMETHYL-SULFOXIDE]

Mononuclear copper(II) and nickel(II) complexes [M(H2L(A))] have been obtained by reaction of the appropriate metal acetate with the potentially hexadentate compartmental ligand H4L(A), prepared by condensation of 2,3-dihydroxybenzaldehyde with ethylenediamine. Physicochemical data suggest the metal ion is in the inner N2O2 compartment. An X-ray investigation on [Cu(H2L(A))] showed that the crystals are orthorhombic, space group Pnca, with a = 19.381 (5), b = 15.327(4), c = 10.158(4) angstrom for Z = 8 and confirms the inner occupancy of copper(II) which exhibits an almost square-planar configuration. The bond lengths to Cu(II) [Cu-N 1.93(1), Cu-O 1.89(1) angstrom (mean)] are within the usual range. The complexes [M(H2L(A))] act as ligands in the formation of heterodinuclear [M1M2L(A)(X)(solv)n] (M1 = Cu or Ni, M2 = La or Y, X = NO3 or Cl) or [M1M2L(A)(solv)n] (M = Cu or Ni, M2 = UO2 or Ba) species [solv = H2O, methanol or dimethyl sulphoxide (dmso)]. Crystals of [{CuY(L(A))(NO3)(dmso)}2].2dmso, grown from dmso-MeOH are triclinic, space group P1BAR, with a = 9.919(5), b = 11.357(5), c = 13.789(6) angstrom for Z = 1 (the asymmetric unit is half of the molecule). The X-ray structure shows that the copper(II) is four-co-ordinated in the inner N2O2 compartment while the yttrium(III) is eight-co-ordinated in the outer O2O2. The complex is a tetranuclear asymmetric unit, two yttrium(III) ions being held together by phenolic oxygen bridges. The Y-O(ligand) bonds are in the range 2.28-2.40 angstrom, Y-O(dmso) is 2.31(1) angstrom and Y-O(nitrate) are 2.48 angstrom(mean). The Cu...Y and Y...Y distances are 3.397(3) and 3.781(2) angstrom respectively. The co-ordination of each yttrium(III) ion is completed by the oxygens of a bidentate nitrate ion and a dmso molecule. The geometry around the metal ion can be described as pentagonal bipyramidal. Two dmso molecules are present in the cell as clathrate solvent. The thermal decomposition of copper(II)-yttrium(III) and -lanthanum(III) complexes and the consequent formation of mixed oxides have also been studied and the preliminary results are reported.