Coordination chemistry of β-ketoamides: Synthesis of copper(II) complexes, x-ray structure of bis-(1- N-benzylamino-1,3-butanedionate)copper(II) and nucleophilic behavior of the metal-β-carbonylenolate ring toward cyanogen and benzoyl cyanide

Abstract

N-monosubstituted β-ketoamides react almost quantitatively with copper(II) acetate in a 1/1 ethanol-water mixture at ca. 40 °C when acetic acid and solvent are removed at reduced pressure. The novel bis(β-ketoamidate)copper(II) complexes, which can be obtained with this synthetic procedure, are O,O′-bonded species, thermally stable both in the solid state and in solution of polar solvents. The crystal structure of bis(1- N-benzylamino-1,3-butanedionate)copper(II) has been determined. Crystals are orthorhombic, space group Pbca with Z = 4, in a unit cell of dimension a = 19.506(5), b = 11.901(4), c = 8.726(3)Å. The structure was solved by the heavy atom method and refined to R = 0.048 for 915 independent reflections. The complex is monomeric and no intermolecular Cu⋯O or Cu⋯N interactions are observed. The bis(benzoylacetanilidate)copper(II) complex reacts with cyanogen or benzoyl cyanide to give addition-insertion at the methino group of the metal-β-ketoamidate ring.