LAUSR

Abstract Formamide and N -methylformamide solutions containing variable amounts of Co(II) and Co(III) halide were employed as model systems to explain the catalytic potential of these ions towards amide bond cleavage reaction. The ν CO downshifts in the IR spectra and the ν CN upshifts in the Raman spectra are in agreement with the stabilization of a molecular structure near the dipolar amide form, which is considered the active species for catalysis. Quantitative analyses performed at the ν CN and δ OCN regions reveal the existence of four- and five-coordinate Co(II) complexes, but the addition of an oxidizing agent leads to the formation of five- and six-coordinate structures around Co(III) in 1:1 and 1:2 (O 2 /Co) type adducts. Attempt to correlate the electrostatic potential with the limiting canonical amide forms is also presented.