Z-Selective and Syndioselective Ring-Opening Metathesis Polymerization (ROMP) Initiated by MonoAryloxidePyrrolide (MAP) Catalysts
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Author(s)
Flook, Margaret M.
Gerber, Laura C. H.
Debelouchina, Galia Tzvetanova
Schrock, Richard Royce
Date Issued
August 2010
Journal
Macromolecules
Publisher
American Chemical Society
Citation
Flook, Margaret M. et al. “Z-Selective and Syndioselective Ring-Opening Metathesis Polymerization (ROMP) Initiated by Monoaryloxidepyrrolide (MAP) Catalysts.” Macromolecules 43.18 (2010): 7515–7522.
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Author's final manuscript
Abstract
We report the Z-selective and syndioselective polymerization of 2,3-bis(trifluoromethyl)bicyclo[2.2.1]hepta-2,5-diene (NBDF6) and 3-methyl-3-phenylcyclopropene (MPCP) by monoaryloxide monopyrrolide imido alkylidene (MAP) catalysts of Mo. The mechanism of polymerization with syn-Mo(NAd)(CHCMe2Ph)(Pyr)(OHIPT) (1; Ad = 1-adamantyl, OHIPT = O-2,6-(2,4,6-i-Pr3C6H2)2C6H3) as the initiator is proposed to consist of addition of monomer to the syn initiator to yield a syn first insertion product and propagation via syn insertion products. In contrast, the mechanism of polymerization with syn-Mo(NAr)(CHCMe2Ph)(Pyr)(OTPP) (4; Ar = 2,6-i-Pr2C6H3, OTPP = 2,3,5,6-Ph4C6H) as the initiator at −78 °C consists of addition of monomer to the syn initiator to yield an anti first insertion product and propagation via anti insertion products. Polymerizations of NBDF6 and MPCP at room temperature initiated by 4 led to polymers without a regular structure. We propose that the syndiotacticity of cis polymers is the consequence of the required inversion at the metal center with each insertion of monomer, i.e., stereogenic metal control of the polymer structure. We also propose that the two mechanisms for forming cis,syndiotactic polymers arise as a consequence of the relative steric bulk of the imido and phenoxide ligands.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
Francis Bitter Magnet Laboratory (Massachusetts Institute of Technology)
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DOI of Published Version
https://doi.org/10.1021/ma101375v
