Probing Stereoselectivity in Ring-Opening Metathesis Polymerization Mediated by Cyclometalated Ruthenium-Based Catalysts: A Combined Experimental and Computational Study.

نویسندگان

  • L E Rosebrugh
  • T S Ahmed
  • V M Marx
  • J Hartung
  • P Liu
  • J G López
  • K N Houk
  • R H Grubbs
چکیده

The microstructures of polymers produced by ring-opening metathesis polymerization (ROMP) with cyclometalated Ru-carbene metathesis catalysts were investigated. A strong bias for a cis,syndiotactic microstructure with minimal head-to-tail bias was observed. In instances where trans errors were introduced, it was determined that these regions were also syndiotactic. Furthermore, hypothetical reaction intermediates and transition structures were analyzed computationally. Combined experimental and computational data support a reaction mechanism in which cis,syndio-selectivity is a result of stereogenic metal control, while microstructural errors are predominantly due to alkylidene isomerization via rotation about the Ru═C double bond.

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Supported Catalysts Useful in Ring-Closing Metathesis, Cross Metathesis, and Ring-Opening Metathesis Polymerization

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Cationic ruthenium alkylidene catalysts bearing phosphine ligands† †Electronic supplementary information (ESI) available: NMR spectra and metathesis data. CCDC 784488. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5dt04506a Click here for additional data file. Click here for additional data file.

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عنوان ژورنال:
  • Journal of the American Chemical Society

دوره 138 4  شماره 

صفحات  -

تاریخ انتشار 2016