Predicting 51V nuclear magnetic resonance observables in molecular crystals

Abstract

Solid-state nuclear magnetic resonance (NMR) spectroscopy and quantum chemical density functional theory (DFT) calculations are widely used to characterize vanadium centers in biological and pharmaceutically relevant compounds. Several techniques have been recently developed to improve the accuracy of predicted NMR parameters obtained from DFT. Fragment-based and planewave-corrected methods employing hybrid density functionals are particularly effective tools for solid-state applications. A recent benchmark study involving molecular crystal compounds found that fragment-based NMR calculations using hybrid density functionals improve the accuracy of predicted ⁵¹V chemical shieldings by 20% relative to traditional planewave methods. This work extends the previous study, including a careful analysis of ⁵¹V chemical shift anisotropy, electric field gradient calculations, and a more extensive test set. The accuracy of planewave-corrected techniques and recently developed fragment-based methods using electrostatic embedding based on the polarized continuum model (PCM) are found to be highly competitive with previous methods. Planewave-corrected methods achieve a 34% improvement in the errors of predicted ⁵¹V chemical shieldings relative to planewave. Additionally, planewave-corrected and fragment-based calculations were performed using PCM embedding, improving the accuracy of predicted ⁵¹V chemical shielding (CS) tensor principal values by 30% and $C_q$ values by 15% relative to traditional planewave methods. The performance of these methods is further examined using a redox-active oxovandium complex and a common ⁵¹V NMR reference compound.