Synthesis of half-sandwich group 4 transition metal catalysts for tandem ring-opening metathesis/vinyl insertion polymerization

Abstract

This work describes the preparation of half-sandwich group 4 transition metal pre-catalysts bearing the 6-[2-(BR2)phenyl]pyrid-2-ylamido (R = ethyl, mesityl) motif and their application in tandem vinyl-insertion-/ring-opening metathesis polymerization as well as detailed NMR studies to highlight the role of the motif and to investigate relevant intermediates in the polymerization process. Catalysts (Zr-2 and Zr-2(CH2SiMe3)2) activated by methylalumoxane (MAO) are capable of producing copolymers with both ring-opening metathesis polymerization (ROMP)- and vinyl-insertion polymerization (VIP)-derived sequences within one single polymer chain. These cyclic olefin copolymers bear the potential for functionalization through polymer-analogous reactions at double bonds present in the copolymers.