Microstructural studies of poly(7-oxabicyclo[2.2.1]hept-2-ene) derivatives prepared from selected ruthenium catalysts
Abstract
The microstructures of polymers prepared from ring-opening metathesis polymerization (ROMP) of 7-oxanorborene (7-oxabicyclo[2.2.11 hept-2-ene) (3), endo-5-(methoxymethyl)-7-oxanorbornene (2), and exo,exo-5,6-bis(methoxymethyl)-7-oxanorbornene (1) with four metathesis catalysts were studied by ^1H and ^(13)C NMR spectroscopy. Tacticities were determined by hydrogenation of the polymers (which removed double-bond isomerism) and also by ROMP of (S)-endo-5-(methoxymethyl)-7-oxanorbornene (2S)(which related head-tail isomerism with tacticity). Polymers prepared from W(CH-t-Bu)(NAr)(OCMe(CF_3)_2)_2 (Ar = 2,6-diisopropylphenyl) (6) have all cis double bonds and are highly syndiotactic, while those from RuCl_3•3H_2O (8) and [RCl(µ-Cl)(η^3:η^3-C_(10)H_(16)]_2 (C_(10)H_(16)) = 2,7-dimethyloctadienediyl) (9) have a high trans double-bond content and are highly isotactic. Polymers prepared from [Ru(H_2O_6](tosylate)_2 (7) exhibit roughly equal amounts of cis and trans double bonds that are randomly distributed in the polymer chain and are atactic. The apparent correlation between double-bond isomerism and tacticity for a classical hexacoordinated metal center is consistent with the model proposed by Ivin and co-workers.
Additional Information
© 1992 American Chemical Society. Received April 22, 1992; Revised Manuscript Received July 8, 1992. Financial support from the National Science Foundation is gratefully acknowledged. A.D.B. thanks Dr. Greg Fu and Zhe Wu for their suggestions in preparing this manuscript.Additional details
- Eprint ID
- 88066
- DOI
- 10.1021/ma00048a006
- Resolver ID
- CaltechAUTHORS:20180720-125619617
- NSF
- Created
-
2018-07-23Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field
- Other Numbering System Name
- Arnold and Mabel Beckman Laboratories of Chemical Synthesis
- Other Numbering System Identifier
- 8727