ISSN:
0025-116X
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
The ring-opening metathesis polymerization of syn- and anti-7-methylbicyclo[2.2.1]hept-2-ene (Ms and Ma) by Mo(CHCMe3)(NC6H3-2,6-i-Pr2)(OCMe3)2 has been followed by 1H and 13C NMR spectroscopy in C6D6 and CD2Cl2 as solvents. The anti monomer Ma polymerizes first, followed much more slowly by the syn monomer Ms, leading to a block copolymer. The reaction is considerably faster in CD2Cl2, where it proceeds to completion, than in C6D6. In C6D6kpa/kia = 9, as determined from the proportion of residual initiator. The double bonds formed are mainly trans (80-90%) in both blocks and the diads embracing the trans double bonds in the Ma blocks have an isotactic bias: (σm)t = 0,69 in C6D6, independent of monomer concentration; the diads in the Ms bloks have a slight tactic bias, probably isotactic. The tacticity is interpreted in terms of control of addition of monomer by the configuration of the chiral carbons in the C5 ring nearest to the molybdenum centre in the propagating metal-carbene complex.
Zusätzliches Material:
3 Tab.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/macp.1992.021930827
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