2017/09/25 by Dylan J. Walsh, Sii Hong Lau, Michael G. Hyatt +1 · 119 citations
Chemistry · Biochemistry, Genetics and Molecular Biology · #Synthetic Organic Chemistry Methods #Chemical Synthesis and Analysis #Catalytic Cross-Coupling Reactions #ROMP #Chemistry #Ring-opening metathesis polymerisation #Polymerization #Metathesis #Catalysis #Norbornene #Pyridine #Polymer chemistry #Living polymerization #Grubbs' catalyst #Salt metathesis reaction #Medicinal chemistry #Organic chemistry #Polymer #Radical polymerization
paper · doi:10.1021/jacs.7b08010
published in Journal of the American Chemical Society 139(39), 13644-13647 (American Chemical Society)
openalex publication_date 2017/09/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/15
The rate of living ring-opening metathesis polymerization (ROMP) of N -hexyl- exo -norbornene-5,6-dicarboximide initiated by Grubbs third-generation catalyst precursors [(H 2 IMes)(py) 2 (Cl) 2 Ru═CHPh] and [(H 2 IMes)(3-Br-py) 2 (Cl) 2 Ru═CHPh] is measured to be independent of catalyst concentration. This result led to the development of a rate law describing living ROMP initiated by a Grubbs third-generation catalyst that includes an inverse first-order dependency in pyridine. Additionally, it is demonstrated that one of the two pyridines coordinated to the solid catalyst is fully dissociated in solution. The monopyridine adduct formation is confirmed in solution by 1 H DOSY (diffusion-ordered NMR spectroscopy), and a Van’t Hoff analysis of the equilibrium between mono- and dipyridine adducts (extrapolated K eq,0 ∼ 0.5 at 25 °C). Finally, the difference in polymerization rates between two catalyst precursors is demonstrated to correspond to the difference in coordination strength between the two pyridines, suggesting that the catalytic species involved in the polymerization’s rate-determining step is not coordinated to pyridine.