ISSN:
0025-116X
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Polymers of exo,exo-, endo,exo, and endo,endo-5,6-dimethylbicyclo[2.2.1]hept-2-ene monomers were prepared using a selection of eight metathesis catalysts and their structures examined by 13C NMR spectroscopy. Tacticities could be determined for the polymers of the endo, endo and endo,exo monomers and for all three hydrogenated polymers. RuCl3 gave hightrans atactic polymers while ReCl5 gave high-cis syndiotactic polymers, but WCl6/Bu4Sn gave a high-cis atactic polymer of the endo,endo monomer. The endo,exo monomer was unusual in giving polymers of relatively low cis content (fraction of cis double bonds σc ≤ 0,3), and with strong exo,endo (XN) bias except in the case of RuCl3. The parallel with the head, tail (HT) biased polymers of 1-methylbicyclo[2.2.1]hept-2-ene is noted. Polymers of the exo,exo and endo,endo monomers have a blocky cis/trans double bond distribution at moderate cis content. The results are discussed in terms of a mechanism involving propagation by metal-carbene, metal-carbene-olefin and metallacyclobutane complexes.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/macp.1987.021880816
Permalink