The chain transfer to monomer reactions promoted by primary and secondary growing chains in the propene polymerization promoted by ansa-zirconocenes and postmetallocene precursors are studied by using DFT methods. From the theoretical results it comes out that the prevalence of propene insertion over beta-hydrogen transfer to the monomer decreases drastically in the presence of a secondary chain. Furthermore, we explained the reason why C-2-symmetric metallocene catalysts promote the selective formation of cis but-2-enyls end group after a 2,1 inserted unit whereas for octahedral bis(phenoxy-imine)titanium-based catalysts, chain release promotes exclusively the formation of allyl terminated chain end. These results might be useful to design ligand precursors able to obtain not only high M-n PP polymers but also tuned chain end groups to build new polymer architectures. Overall, a more general picture of the enantioselectivity of the chain transfer to monomer processes is reported. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 699-708, 2010