Polymerization reactions of propylene and three higher linear 1-alkenes, 1-hexene, 1-octene and 1-decene, were carried out with post-metallocene catalysts derived from Ti complexes I and II with a bidentate phenol-alcohol (saligenin-type) ligand derived from 2,4-di-tert-buty1-6-(1,1,1,3,3,3-hexafluoro-2-hydroxy-propan-2-yl)phenol, in the presence of two cocatalysts, MAO and a combination of AlEt2Cl and MgBu2. All catalyst systems contain a large variety of active centers and produce both amorphous atactic polymers and partially crystalline isotactic material. The AlEt2Cl-MgBu2 cocatalyst produces significantly more active catalyst systems. Analysis of C-13 NMR data for the propylene polymers shows that the mechanism of isotactic chain growth is principally different for the active centers formed in the presence of the two cocatalysts. (C) 2013 Elsevier Ltd. All rights reserved.