Highly selective molybdenum ONO pincer complex initiates the living ring-opening metathesis polymerization of strained alkynes with exceptionally low polydispersity indices.

ABSTRACT: The pseudo-octahedral molybdenum benzylidyne complex [TolC?Mo(ONO)(OR)]·KOR (R = CCH3(CF3)2) 1, featuring a stabilizing ONO pincer ligand, initiates the controlled living polymerization of strained dibenzocyclooctynes at T > 60 °C to give high molecular weight polymers with exceptionally low polydispersities (PDI ? 1.02). Kinetic analyses reveal that the growing polymer chain attached to the propagating catalyst efficiently limits the rate of propagation with respect to the rate of initiation (kp/ki ? 10(-3)). The reversible coordination of KOCCH3(CF3)2 to the propagating catalyst prevents undesired chain-termination and -transfer processes. The ring-opening alkyne metathesis polymerization with 1 has all the characteristics of a living polymerization and enables, for the first time, the controlled synthesis of amphiphilic block copolymers via ROAMP.

SUBMITTER: Bellone DE 

PROVIDER: S-EPMC4308759 | biostudies-literature | 2015 Jan

REPOSITORIES: biostudies-literature