Benzoylacetanilide complexes of copper(II)

The synthesis of twenty copper(II) complexes of benzoylacetanilides variously substituted in the anilide ring, is described. Their general formula is [CuL₂] (L = 3- or 4-substituted benzoylacetanilide anion. Contrary to an earlier report, the complexes have normal magnetic moments (μ_eff ∼ 1·8 B.M. at 295 K). The green complexes with substituents in the 3-position of the anilide ring undergo solvent adduction by methanol to yield brown complexes of formula [CuL₂ (methanol)₂]. Copper-oxygen stretching frequencies are assigned to infrared bands which shift in the sequence of the electronic effects of the substituents. A band near 30 kK (1 kK = 10³ cm⁻¹) in the electronic spectra is assigned to the ligand π3→ π4∗ role=presentation style=font-size: 90%; display: inline-block; position: relative;>$\text{π}{}_3\text{→ π}{}_4{}^1$$\text{π}{}_3\text{→ π}{}_4{}^1$ transition. The shift towards lower energies induced in this band by substituents with electron withdrawing resonance effects indicates that metal-ligand π-bonding is not significant in copper(II) benzoylacetanilide complexes. Intense absorption near 40 kK is assigned to a σ_L → 3d_xy transition. Weak d → d bands occur near 15 kK.