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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

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posted on 20.07.2020, 11:37 authored by Mark A. Wallace, Peter Y. Zavalij, Lawrence R. Sita
The homochiral, configurationally stable, C1-symmetric dimethyl, pentamethylcyclopentadienyl, N-(S)- or N-(R)-1-phenylethyl-caproamidinate hafnium preinitiators (SC,SHf)-1 and (RC,RHf)-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.