Synthesis of Thermoplastic Elastomers by Yttrium-Catalyzed Isospecific <i>Trans</i>-1,4-Polymerization of (<i>E</i>)-1,3-Pentadiene

Regio- and stereoselectivity control in the polymerization of 1,3-conjugated dienes is much interest importance. We report herein for first time isospecific trans-1,4-selective living (E)-1,3-pentadiene (EPD) by a C5H5-ligated yttrium catalyst (C5H5)Y(CH2C6H4-NMe2-o)2/[Ph3C][B(C6F5)4], which afforded crystalline isotactic-trans-1,4-polypentadiene showing good elastic properties without vulcanization (tensile strength up to 7.1 MPa with elongation at break 2600%). The DFT calculations revealed that was mainly due steric repulsion between C5H5 ligand methyl group EPD. controlled has been achieved use half-sandwich catalyst. resulting polymers showed high tensile (up 2600%) vulcanization.