Employing vibrational spectroscopy to confirm the catalytic activity of Ce(III) and Cr(III) towards amide bond cleavage

The dependence of the Ce(III) and Cr(III) halide concentration on the spectrum of formamide is investigated for the first time. The downshifts observed for the νCO mode in the IR spectra and the upshifts of the νCN vibration in the Raman spectra are consistent with the stabilization of the HO−CN+H2 form, which is directly involved in the amide bond cleavage reaction. The νCN region was used for the quantitative treatment and reveals that Ce(III) is surrounded by 8 formamide molecules, in a square prismatic arrangement, while 4 formamide molecules are around Cr(III) and the counter-ion occupies two vertices of the octahedron in the cis-configuration. The spectral changes in the region of the solvent are in excellent agreement with those observed for the metal-ligand vibrations.