N‑Substituted Iminocaprolactams as Versatile and Low Cost Ligands in Group 4 Metal Initiators for the Living Coordinative Chain Transfer Polymerization of α‑Olefins

A new structurally diverse ligand for metal complexes, the (κ²-N,N)-iminocaprolactam group, that can be obtained in large bulk quantities from inexpensive and readily available starting materials, is introduced. In the present report, the ability of this family of ligands to provide a viable substitute for the acyclic amidinate moiety of a class of cationic monocyclopentadienyl, amidinate (CPAM) group 4 metal initiators for the living coordination polymerization (LCP) and living coordinative chain transfer polymerization (LCCTP) of α-olefins is documented through the synthesis of (η⁵-C₅Me₅)­Hf­[(R)­N^imcapN]­(Me)₂ [R = benzyl (1), CH₂(1-naphthyl) (2), and tert-butyl [C­(CH₃)₃] (3)] as preinitiators for the (stereoselective) LCP and LCCTP of propene.