Regio‐ and Stereochemical Control in Ocimene Polymerization by Half‐Sandwich Rare‐Earth Metal Dialkyl Complexes

The polymerization of ocimene has been first achieved by half‐sandwich rare‐earth metal dialkyl complexes in combination with activator and AlⁱBu₃. The regio‐ and stereoselectivity in the ocimene polymerization can be controlled by tuning the cyclopentadienyl ligand and the central metal of the complex. The chiral cyclopentadienyl‐ligated Sc complex 1 prepares syndiotactic cis‐1,4‐polyocimene (cis‐1,4‐selectivity up to 100%, rrrr = 100%), while the corresponding Lu, Y, and Dy complexes 2 – 4 and the achiral pentamethylcyclopentadienyl Sc, Lu, and Y complexes 5 – 7 afford isotactic trans‐1,2‐polyocimenes (trans‐1,2‐selectivity up to 100%, mm = 100%).