Kinetics of incorporation of copper(II) into meso-tetraphenylporphine in dimethylformamide. Effect of carboxylate anions

The kinetics of incorporation of copper(II) into meso-tetraphenylporphine dimethylformamide, at 30°, were dependent on the copper salts employed. The reaction was first-order in total concentration of Cu(II) perchlorate, whereas half-order in that of Cu(II) acetate. At constant Cu(II) concentration, the reaction was accelerated by the addition of acetate anion(Ac), until at a ratio [Ac]/[Cu(II)] of unity it was almost ten times faster than the reaction with Cu(II) perchlorate; an increase of the ratio past unity caused a rate decrease. From this unusual acetate dependence and effect of water content in the solvent, it was concluded that the species CuAc⁺ was the most reactive and the dimeric species, Cu₂Ac₄, was unreactive. Similar rate-concentration relationships were obtained with formate, propionate and benzoate anions. Bidentate ligands such as phthalate and phenylalaninate anions did not increase the rate.