Cationic group 4 metal alkyl complexes containing tetradentate Schiff
base ligands, (acen)Zr(R)(+) and (F-6-acen)Zr(R)(+), are prepared by p
rotonolysis of suitable neutral dialkyl precursors. These complexes di
splay electrophilic behavior and are moderately active ethylene polyme
rization catalysts in the presence of 1 molar equivalent of AlR(3).