Identification of the reaction products of iron complexes by the vibrational spectrum using the example of iron hydroxocation [Fe(OH)$_{2}$(H$_{2}$O)$_{2}$]$^{+}$ in an aqueous medium

The change in the vibrational spectrum of iron hydroxocation [Fe(OH)$_{2}$(H$_{2}$O)$_{2}$]$^{+}$ in the course of its interaction with peroxynitrite [NO–О$_2]^-$ in an aqueous medium described by the PCM-SMD model was investigated in order to identify the reaction products, primarily nitrogen dioxide. The quantum-chemical calculation of the complex by the CASSCF method is identical to that previously used in the description of reactions in the active center of the tubercular bacillus M. tuberculosis (trHbN). The reaction products in these processes are compared, and the most characteristic vibration frequency is found, which makes it possible to establish the appearance of nitrogen dioxide. The energetic effect in the reverse process, the capture of nitrogen dioxide by the iron complex, has been estimated.