Calculation of ligand NMR chemical shifts in transition-metal complexes using ab initio effective-core potentials and density functional theory

A combination of ab initio effective-core potentials and sum-over-states density functional perturbation theory has been used to calculate 13C NMR chemical shifts in a series of transition-metal organometallic complexes, up to and including sixth-period species. Thus, for the first time both electron correlation and scalar relativistic effects have been included in chemical shift calculations. The good agreement with experiment indicates that this methodology is a powerful new tool to predict and rationalize ligand NMR chemical shifts in organometallic and inorganic transition-metal complexes. Sources of remaining discrepancies to experiment are discussed.