Infrared spectra of metal-free, N′,N-dideuterio, and magnesium porphyrins: density functional calculations

Infrared frequencies and intensities for the metal-free porphyrin (H2Por), N′,N-dideuterio porphyrin (D2Por), and magnesium porphyrin complex (MgPor) have been calculated at density functional B3LYP level using the 6-31G(d) basis set. Detailed assignments of the NH and NM vibrational bands in the IR spectra have been made on the basis of comparison between the calculated data and the experimental results. The previous empirical controversial assignments for the bands at 1224, 1110 and 771 cm−1 for metal-free porphyrin are also clearly interpreted.