Enantioselective Living Coordinative Chain Transfer Polymerization: Production of Optically Active End-Group-Functionalized (+)- or (−)-Poly(methylene-1,3-cyclopentane) via a Homochiral <i>C</i><sub>1</sub>-Symmetric Caproamidinate Hafnium Initiator
Mark A. Wallace, Peter Y. Zavalij, Lawrence R. Sita
Abstract
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.