A Theoretical Assessment of the Thermodynamic Preferences in the Cyclopalladation of Amines

The factors affecting the cyclopalladation of amines are explored by a comparison of the energy differences between the cyclopalladated amine and the free ligand for a series of compounds. Four factors are considered: the substituents in the nitrogen atom (primary vs. tertiary amines), the hybridization (sp2 or sp3) of the metalated carbon atom, the number of members in the metallacycle ring (four, five, or six), and the presence of electron-donor or -acceptor groups. The trends that arise from these calculations, performed at the B3LYP level of theory, are compared with the experimental data available.