Synthesis, Spectral Studies and Reactivity of Nickel(II), Copper(II) and Zinc(II) Mixed Ligand Complexes with 2-Formyl-, 2-Acetyl- and 2-Benzoyl- Cyclohexanones and Acetylacetone

Abstract

Mixed ligand metal(II) complexes of the type [ML{XC(COCH₃)₂} (H₂O)_n] [M = Cu(II), Ni(II) and Zn(II); L = 2-formyl-, 2-acetyl- or 2-benzoyl- cyclohexanone; X = H, Cl, Br, CONHPh; n = 0,1,2] have been prepared and characterized by elemental analyses, magnetic measurements, infrared, ¹H NMR, EPR and electronic spectral studies. The halogenation of the parent complexes with N-bromosuccinimide and N-chlorosuccinimide caused substitution at the τ -positionintheacetylacetonering. Reactionsofthe complexes with phenylisocyanate produced monoamides. The UV and IR spectra of the products and the ¹H NMR spectra of the complexes are all consistent with τ-substitution. The copper(II) complexes are anhydrous and square-planar whereas thedihydratednickel(II)complexesareoctahedral. Zinc (II) complexes are monohydrated. In the mixed ligand complexes ν(C=O). is sensitive to the metal coordinated to it in contrast to that observed in bisacetylacetonates. EPRspectralstudiesofcopper(II)complexesindicatethat they are square-planar with ^dx²-y² ground state. MO coefficientsderived from EPR parametersshowthat the mixed ligand complexes are more covalent then the corresponding bis-chesates.