Controllable ROMP Tacticity by Harnessing the Fluxionality of Stereogenic-at-Ruthenium Complexes.

Readily accessible and easy-to-handle Ru complexes capable of generating all-Z polynorbornene and polynorbornadiene by ring-opening metathesis polymerization (ROMP) with controllable selectivity, ranging from ≈50 to ≥95% syndiotactic, are introduced. It is demonstrated that the rate of non-metathesis based polytopal isomerization and levels of syndiotacticity may be fine-tuned by the adjustment of monomer concentration and catalyst's steric and electronic characteristics.