Towards clarifying the N-M vibrational nature of metallo-phthalocyanines: Infrared spectrum of phthalocyanine magnesium complex: Density functional calculations

Infrared frequencies and intensities for the magnesium phthalocyanine complex MgPc have been calculated at density functional B3LYP level using the 6-31G(d) basis set. Detailed assignments of the metal-nitrogen (N-M) vibrational bands in the IR spectrum have been made on the basis of comparison of the calculated data of MgPc with the experimental result and also with that of H₂Pc. The empirical controversial assignment of the characteristic band at 886-919cm^-1 for metallo-phthalocyanines is also clearly interpreted. Nevertheless, the previous assignments of N-H stretchings, in-plane bending (IPB) and out-of-plane bending (OPB) modes made based on the comparative calculation of H₂Pc and D₂Pc are confirmed again by the present research result.