Building ligand knowledge bases for organometallic chemistry: Computational description of phosphorus(III)-donor ligands and the metal–phosphorus bond

Changing the coordinated ligands is a powerful and synthetically convenient way of modifying and fine-tuning the properties of transition metal complexes, especially those active in homogeneous catalysis. Parameters capturing such changes in the steric and electronic characteristics of complexes have played a key role in improving our understanding of ligand effects on the kinetic, thermodynamic, spectroscopic and structural behaviour of such species. Such ligand parameters can be useful for interpreting experiments, but they can also guide the discovery of novel ligands from ligand maps and allow the prediction of ligand effects before further experimentation. The latter aims especially are best served if such parameters can be determined before ligands and complexes have been synthesised, and here we review calculated descriptors for phosphorus(III) ligands as widely used in organometallic and coordination chemistry. We also discuss the application of such ligand descriptors in models, maps and predictions of ligand effects, describe related computational studies of the metal–phosphorus bond, and provide an overview of the statistical methods used.