A DFT Protocol for the Prediction of P-31 NMR Chemical Shifts of Phosphine Ligands in First-Row Transition-Metal Complexes

摘要

While P-31 NMR is a major technique to characterize phosphine-ligated transition-metal complexes-which are ubiquitous in catalysis-P-31 NMR chemical shifts are difficult to predict using empirical rules or tabulated data. Aiming at filling this gap, we propose here guidelines enabling their prediction at a modest computational cost. Rooted in density functional theory, our protocol features structural optimization and magnetic shielding tensor calculations performed at a global hybrid level using a tailored locally dense basis set. Validation on an experimental data series revealed that while a careful conformational analysis is required in the case of flexible phosphines, the use of the free ligand or another complex as a reference for chemical shifts often allows solving this drawback. Applicability to various diamagnetic complexes of first-row transition metals is demonstrated, including large systems relevant to contemporary catalysis.