CHARACTERIZATION OF COPPER(II), NICKEL(II), COBALT(II) AND PALLADIUM(II) COMPLEXES OF VICINAL OXIME-IMINE LIGANDS - INDUCED CHELATE ISOMERISM IN THE SAME MOLECULE OF THE NICKEL(II) COMPLEX
Mm. Aly et Sm. Imam, CHARACTERIZATION OF COPPER(II), NICKEL(II), COBALT(II) AND PALLADIUM(II) COMPLEXES OF VICINAL OXIME-IMINE LIGANDS - INDUCED CHELATE ISOMERISM IN THE SAME MOLECULE OF THE NICKEL(II) COMPLEX, Monatshefte fuer Chemie, 126(2), 1995, pp. 173-185
Metal complexes of the title ligands were characterized in order to de
termine the factors influencing the stability of chelate isomerism in
the same molecule. The ligands were prepared by 1:1 condensation of is
onitrosoacetylacetone (Hiso) with either o-aminophenol (H(2)isoaph), p
-aminophenol (H(2)isopph), or aniline (Hisoanil). The following comple
xes have been synthesized: [(isoaph)Cu](4), (Hisoaph)(2)Co, (Hisopph)(
2)M . H2O (M = Ni(II), N = 2; M = Pd(II), n = 0; M = Co(II), n = 2), [
(isopph) Cu . H2O](2), and (isoanil)(2)M (M = Ni(II), Cu(II), Co(II),
or Pd(II)). Both chelate rings in these metal complexes are five-membe
red. Transimination of one -C=N-C6H5 group to -C=NH in (isoanil)(2)Ni
produced a six-membered chelate ring in (isoim)Ni(isoanil). The induce
d chelate isomerism is ascribed to intermolecular hydrogen bonding of
the imino-hydrogen and the basic nitrogen of the same six-membered che
late ring of an adjacent square planar molecule. Other types of hydrog
en bondings with the oximato oxygen (intra- or intermolecular) favour
the formation of five-membered chelate rings. Analytical, spectroscopi
c, and magnetic moment data are in accordance with the suggested formu
lations.