Synthesis of Titanium, Zirconium, and Hafnium Complexes That Contain the [(MesitylN-o-C₆H₄)₂O]²⁻ Ligand

(MesitylNH-o-C6H4)2O (H2[MesNON]) has been synthesized in ∼70% yield, and several [MesNON]2- complexes of Ti, Zr, and Hf have been prepared, in particular a variety of dialkyl complexes, [MesNON]MR2 (M = Zr, R = Me, CH2CMe3, Ph; M = Hf, R = Me, Et, CH2CHMe2, CH2CMe3, Ph). [MesNON]ZrMe2 can be activated with [Ph3C][B(C6F5)4] or [PhNMe2H][B(C6F5)4], but the resulting cationic species will only oligomerize 1-hexene. We conclude that the sterically bulky tert-butyl groups in [(R‘N-o-C6H4)2O]2- systems are necessary for the success of [R‘NON]2- Zr catalyst systems for the living polymerization of 1-hexene.