POLYMERIZATION OF NORBORNENE BY OLEFIN METATHESIS CATALYSTS - INSERTION AND RING-OPENING IN THE SAME CHAIN

Investigation of the homopolymer of norbornene prepared with Re or Mo catalysts showed that propagation occurs by an insertion process with an occasional ring-opening step in the same chain. Evidence comes from NMR spectrometry, where DEPT spectra of the polymer show the disappearance of some olefinic carbons that do not have hydrogen atoms attached to them. Ozonolysis of the polymer supports the NMR indications. Finally, polymerization of 2,3-dideuterionorborene and C-13{H-2} polarization transfer NMR studies on the polymer show that deuterium is transferred, likely by alpha-D migration to the metal, from the 2-position on norbornene to a methylene group. To the best of our knowledge, this C-13{H-2} polarization transfer NMR experiment represents the first application of the method to the selective detection of small amounts of unique structural components in a polymer. An inverse temperature relationship on the extent of ring opening was found for both catalysts.