ISSN:
0025-116X
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Ring-opened polymers of racemic and optically active 5,5-dimethylbicyclo[2.2.1]hept-2-ene (6) (5,5-dimethylnorbornene), with cis double bond contents of 0-100%, were prepared using various Mo-, W-, Re-, Os-, Ru-, and Ir-based olefin metathesis catalysts. The 13C NMR spectra of these polymers are interpreted in terms of TH, TT, HH, HT structures (T = tail, H = head, referring to the orientation of the methyl groups), also tt, tc, ct, cc structures (t = trans, c = cis double bonds), and m, r dyads (m = meso, r = racemic, referring to the relative configuration of adjacent cyclopentane rings in the chains). m/r splitting is observed for both the olefinic carbon (C3) and the adjacent ring carbon (C4) in the HH structures of the all-trans polymer made from racemic monomer using RuCl3 as catalyst. All-cis polymers are fully syndiotactic while all-trans polymers have 58% isotactic (m) and 42% syndiotactic (r) dyads. A consistent set of substitution parameters is derived, the effect of two methyl substituents on the 13C chemical shifts being generally a little less than the sum of the effects of the individual substituents.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/macp.1982.021830705
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