Use of Computational and Synthetic Chemistry in Catalyst Design: A New Family of High-Activity Ethylene Polymerization Catalysts Based on Titanium Tris(amino)phosphinimide Complexes

DFT calculations of the mechanism of polymerization for the series of catalyst models
derived from CpTiMe2(NPR3) (R = Me, NH2, H, Cl, F) demonstrate the critical role of ion
pairing in determining the overall barrier to polymerization and suggest that electron-donating substituents reduce this barrier. Based on these results, a family of precatalysts
of general formula Cp‘TiX2(NP(NR2)3) (X = Cl, Me) were developed. This approach using
computational methods to guide the synthetic efforts has afforded a new, readily accessible,
and easily varied family of highly active ethylene polymerization catalysts based on titanium
tris(amino)phosphinimide complexes.