Can low-valent silicon compounds be better transition metal ligands than phosphines and NHCs?

We investigated the potential application of experimentally characterized low-valent silicon compounds as transition metal ligands by computing the most important ligand properties, sigma-donor and pi-acceptor ability, ligand-to-metal charge transfer, and steric parameters and compared them to the generally used carbene and phosphine ligands. We found that several recently synthesized donor-stabilized low-valent silicon compounds can compete or even exceed the favorable features of commonly used carbene and phosphine ligands regarding all investigated ligand properties. We derive the general principles behind the enhanced features and conclude how even better low-valent silicon ligands can be designed with a slight modification of known compounds. Using our results as a database, one can choose an appropriate silicon-based ligand for transition metal catalysis.