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)ZrMe2 complex (1) was synthesized and activated with B(C6F5)(3) obtaining an ion pair (2) having the MeB(C6F5)(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 1 to cis(N,N)-cis(O,O) in the ion pair 2.