Solvent and spin state effects on molecular structure, IR spectra, binding energies and quantum chemical reactivity indices of deferiprone-ferric complex: DFT study

Abstract

In this work, in order to determine the solvent and spin state effects on the molecular<br><br>structure of deferiprone-ferric complex ([Fe(DFP)3]), density functional theory (DFT)<br><br>calculations were performed at the CAM-B3LYP/6-31G(d) level of the theory. The results<br><br>indicate that the stability and binding energy of [Fe(DFP)3] in the polar solvents are higher<br><br>and lower, respectively, than non-polar ones. The analysis of the spin state energies of the<br><br>complexes showed that the corresponding stability constants increase with the spin states<br><br>increment. The binding energies in high-spin state is higher than intermediate- and low-spin<br><br>states which showed that the complex formation in a high-spin state is more favorable.<br><br>Furthermore, the evaluation of the IR spectrum in the various solvents reveals that the<br><br>intermolecular hydrogen bond formation between the oxygen atom of the carbonyl group<br><br>and the hydrogen atom of the solvent causes a spectral red shift. Because of the importance<br><br>of the charge transfer in the complex formation, donor-acceptor interaction energies were<br><br>evaluated. Based on this analysis, lone pair electrons of the oxygen atom interact with the<br><br>2<br><br>antibonding orbitals of the iron, more than the other possibilities. Finally, some probable<br><br>correlations between the quantum chemical reactivity indices of the complexes and solvent<br><br>polarity were considered. According to the obtained results, an enhancement in the<br><br>dielectric constant of the solvent decreases the electrophilicity index while the electronic<br><br>chemical hardness increases. Recent study indicates a linear correlation between chemical<br><br>hardness and binding energies of [Fe(DFP)3] complex.