Density functional theory calculations of nitrogen hyperfine and quadrupole coupling constants in Oxovanadium(IV) complexes

Relativistic density functional theory (DFT) calculations of nitrogen hyperfine and quadrupole coupling constants were conducted for a series of oxovanadium complexes with axial and equatorial nitrogen ligands. The computational results qualitatively reproduced the observed experimental trends in nitrogen hyperfine coupling constants with ligand type (amine, imine, and isothiocyanate) and coordination (axial vs equatorial). The best quantitative agreement between calculated and experimental nitrogen coupling constants was obtained using the scalar-relativistic, spin-unrestricted, open-shell Kohn-Sham (SR UKS) method. These results have important implications for the interpretation of high-resolution electron paramagnetic resonance (EPR) spectra of oxovanadium complexes with nitrogen ligands.