Effect of ligand structure on activation rate constants in ATRP

Activation rate constants (kact) for Cu complexes with various nitrogen-based ligands for Cu-mediated ATRP were determined at 35 °C in acetonitrile. The ratio of kact for complexes with different ligands exceeds 1 million times. The general order of Cu complex activity for ligands is tetradentate (cyclic-bridged) > tetradentate (branched) > tetradentate (cyclic) > tetradentate (linear) > tridentate > bidentate ligands. The nature of nitrogen atoms in ligands also plays a significant role in the activity of the Cu complexes and follows the order pyridine ≥ aliphatic amine > imine.