Synthesis and Spectroscopic Studies of Bismuth(III) Iodide Porphyrins
Synthesis of bismuth complexes of etioporphyrin II, protoporphyrin IX dimethyl ester and three tetraphenylporphyrin derivatives in which iodine atom is an extraligand, was carried out. Obtained compounds were characterized by mass spectrometry, UV-vis, 1H NMR spectroscopy, and HPLC. The study of X-ray spectra showed that bismuth valence is +3. Bismuth atom coordinates four nitrogen atoms and one iodine atom. All four nitrogen atoms have equivalent binding energies. IR absorption spectra of free porphyrins bases and their bismuth complexes were studied. The comparison of IR absorption spectra of neat porphyrins shows no significant differences in vibrations of nitrogen-carbon cycles. As for bismuth complexes, vibrations bands of bismuth-iodine bonds ν(Bi-I) appear at 90–130 cm-1 in the long-wavelength spectra regions, as well as deformation vibrations involving bismuth, iodine and nitrogen atoms δ(NBiI) with frequencies 150–165 cm-1, deformation vibrations of δ[BiN4] pyramid at ~300 cm-1 and stretching vibrations bands of this complex fragment involving deformations of nitrogen-carbon ring, in the region of 335–375 cm-1. Quantum-chemical calculations were conducted including calculations of the vibrational spectra, dipole moments, and charge distribution on atoms (according to Mulliken). It was found that complex of bismuth iodide with etioporphyrin II is the most polar among the studied series compounds.