Experimental Study and Modeling of the UV–Vis and Infrared Spectra of the [VO(O₂)Hheida]⁻ Complex Dissolved in Water

Combined theoretical and experimental studies of the [VO­(O₂)­Hheida]⁻ anion dissolved in water that may serve as a functional model for vanadium haloperoxidase enzymes have been performed. The geometrical structure and absorption and vibrational spectra of this system have been evaluated within the framework of density functional theory (DFT). The obtained theoretical results on the equilibrium structure and optical spectra are in quite good agreement with the experimental data. With the aid of the combination of UV–visible spectroscopy and electronic structure calculations, it has been revealed that, in the apparent absorption spectra of the [VO­(O₂)­Hheida]⁻ anion, the highest in energy band corresponds to a ligand to metal electron excitation, while the band with a maximum at 430 nm arises from the peroxo group. The calculations also reproduce quite well the positions, intensities and the grouping of frequencies in the near-infrared (NIR) spectra. The visualization of the calculated vibrations in the energy range of 400–1100 cm^–1 has been presented