Synthesis and study of cobalt(II), nickel(II), copper(II) and zinc(II) complexes of 2-formyl- and 2-acetyl-cyclohexanones

Abstract

Metal(II) complexes of the type ML₂nB[M = Co(II), Ni(II), Cu(II) and Zn(II); L = 2-formy1- or 2-acetyl-cyclohexanone; B = H₂O, Py; n =0,2] have been prepared and characterized by elemental analyses, molar conductance, IR, electronic and NMR spectra, and magnetic susceptibility studies. The copper complexes possess square-planar geometry whereas the nickel and cobalt diaquates possess octahedral environment. The corresponding anhydrides are polymeric and possess high-spin octahedral configuration. All the base adducts possess high-spin octahedral configuration with a tendency towards dissociation in solution. IR and PMR spectra of the ligands and complexes indicate that the formylcyclohexanone coordinates in the hydroxymethylene form whereas the acetylcyclohexanone coordinates in the cyclohexene form. The order of the stabilities, namely Cu > Ni > Co > Zn, derived from v(M - O), parallels the crystal field stabilization energy.