H-1 and H-2 NMR spectroscopic characterization of the V(III) ion-pair intermediates formed upon the activation of alpha-diimine vanadium(III) chloride (L3.5-MeVCl3)-Cl-III(THF) (L3.5-Me = 1,4-bis-3,5-dimethylpheny-12,3-dimethyl-1,4-diazabuta-1,3-diene) with AlMe3/[Ph3C][B(C6F5)](4) and MAO is reported. In contrast to previously reported heterobinuclear ion pairs of the type [L-1(R)V-III(mu-R)(2)AlMe2](+)[A](-)(L-1 = bis(imino)pyridine ligand, [A](-) = [B(C6F5)(4)](-) or [MeMAO](-), R = Me or Cl), species of the type [L3,5-MeVMe2(THF)(2)](+) [B(C6F5)(4)](-) [L3,5-MeVMe2(THF)(2)](+)[MeMAO](-) and [L3,5-MeVMe2+ <- MeMAO(-)] were identified. (C) 2016 Elsevier B.V. All rights reserved.