Stereochemistry of copper (II), nickel (II) and cobalt (II) 2'-hydroxy-5'-X-chalconeoxime complexes

Abstract

Cu (II), Ni (II) and Co (II) complexes of the type ML2,2B where L = 2'-hydroxy-5'-X-chalconeoxime (X = H, CH₃, Cl) and B = water or pyridine have been obtained from chalconeoximes and by reacting the preformed metal (II) chalcone complexes with hydroxylamine. They have been characterised on the basis of elemental and thermal analyses, conductivity and magnetic measurements and ligand field and m spectra. All the complexes are high-spin octahedral species in contrast to the low-spin square planar Ni (II) and Co (II) salicylaldoxime complexes. IR spectral studies indicate that conjugation is relatively damped in chalconeoxime. The lower ligand field strangth of the oxime is attributed to the weak M-N bonding and less extensive dπ -π^∗ 3 back-bonding. Replacement of water by pyridine weakens metal-oximino bond in the complexes.