Activation of a bis(phenoxy-amine) precatalyst for olefin polymerisation: first evidence for an outer sphere ion pair with the methylborate counterion.

A bis(phenoxy-amine)ZrMe(2) complex (1) was synthesized and activated with B(C(6)F(5))(3) obtaining an ion pair (2) having the MeB(C(6)F(5))(3)(-) counterion in the second coordination sphere as deduced by NMR studies. Both DFT calculations and NMR investigations suggest that the activation is coupled with a change of the binding modality of the tetradentate ligand from cis(N,N)-trans(O,O) in the octahedral dimethyl precursor to 1 cis(N, N)-cis(O,O) in the ion pair 2.