Enantioselective Living Coordinative Chain Transfer Polymerization: Production of Optically Active End-Group-Functionalized (+)- or (−)-Poly(methylene-1,3-cyclopentane) via a Homochiral C₁‑Symmetric Caproamidinate Hafnium Initiator

The homochiral, configurationally stable, C₁-symmetric dimethyl, pentamethylcyclopentadienyl, N-(S)- or N-(R)-1-phenylethyl-caproamidinate hafnium preinitiators (S_C,S_Hf)-1 and (R_C,R_Hf)-1, respectively, can be used in combination with the borate coinitiator [PhNHMe₂]­[B­(C₆F₅)₄] (B) and excess equivalents of ZnEt₂ for the enantioselective living coordinative chain transfer polymerization (LCCTP) of 1,5-hexadiene to provide (+)- and (−)-poly­(methylene-1,3-cyclopentane) (PMCP) of tunable molecular weight and very narrow polydispersity. Use of excess I₂ to quench LCCTP provides the corresponding (+)- and (−)-iodo-terminated PMCP products. This enantioselective LCCTP process serves to establish access to readily available, practical, and scalable quantities of optically active liquid crystalline end-group-functionalized xPMCP building blocks for material science and technology discovery.