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Metathesis polymerization of exo , exo ‐, endo , exo ‐ and endo , endo ‐5,6‐dimethylbicyclo[2.2.1]hept‐2‐enes; microstructure of the polymers and their hydrogenated products

1987; Wiley; Volume: 188; Issue: 8 Linguagem: Inglês

10.1002/macp.1987.021880816

0025-116X

Ruth M. E. Greene, K. J. Ivin, G. Malachy McCann, John J. Rooney,

Asymmetric Hydrogenation and Catalysis

Abstract 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 13 C NMR spectroscopy. Tacticities could be determined for the polymers of the endo , endo and endo , exo monomers and for all three hydrogenated polymers. RuCl 3 gave hightrans atactic polymers while ReCl 5 gave high‐cis syndiotactic polymers, but WCl 6 /Bu 4 Sn 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 σ c ≤ 0,3), and with strong exo , endo (XN) bias except in the case of RuCl 3 . 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.