Quantum-chemical analysis of the spectra of metal complexes of azaporphyrins by the INDO/S method

The electronic spectra of the complexes of tetraazaporphyrin and phthalocyanine with Cu, Ni, Co, Fe, and Mn have been calculated by the INDO/S method. Electron correlation has been taken into account by considering 210 singly excited configurations according to a method which permits the calculation of the spectra of complexes with singlet, doublet, and triplet ground states. Test calculations of the complexes of porphyrin with Fe and Co have been carried out, and the results have been compared with known results from nonempirical calculations. The energies of the orbitals of the ligand of the π and σ types correlate with the corresponding peaks in the photoelectron spectra of azaporphyrins. The energies of the electronic transitions found are consistent with the experimental values.