Premium
13 C NMR spectra of tactic and atactic hydrogenated ring‐opened polymers of enantiomeric and racemic endo , exo ‐5,6‐dimethylnorbornene
Author(s) -
Ivin Kenneth J.,
Kenwright Alan M.,
Hofmeister Gretchen E.,
McConville David H.,
Schrock Richard R.,
AmirEbrahimir Valia,
Carvill Andrew G.,
Hamilton James G.,
Rooney John J.
Publication year - 1998
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(19980401)199:4<547::aid-macp547>3.0.co;2-u
Subject(s) - tacticity , monomer , polymer , polymer chemistry , triad (sociology) , materials science , copolymer , polymerization , carbon 13 nmr , catalysis , chemistry , crystallography , organic chemistry , psychology , psychoanalysis
Polymers 1 of the title monomer, prepared using well‐defined molybdenum carbene complexes as catalysts, have been hydrogenated and the structures of the resultant polymers 2 examined by 13 C NMR spectroscopy. The hydrogenated polymer made from the all‐ cis isotactic polymer of (±)‐monomer showed a single set of 13 C NMR lines as expected for an NX sequence of endo (N) and exo (X) substituents. The hydrogenated polymer made from a cis isotactic polymer of (±)‐monomer showed additional fine structure arising from the random incorporation of both enantiomers in the isotactic polymer chain: four equal lines for C‐9 (orientational triad sensitivity), two equal lines for C‐3, C‐4, C‐5, and C‐1 (dyad sensitivity), but single lines for C‐8, C‐2, C‐7 and C‐6 (insensitive to the relative orientation of adjacent repeating units). The hydrogenated polymer made from a trans atactic polymer of (±)‐monomer showed fine structure due to the presence of both m and r dyads. That made from a trans atactic polymer of (±)‐monomer contains 16 possible triad sequences and gave a more complicated spectrum. A complete assignment was made for the first three polymers and a partial assignment for the fourth. Polymers made using non‐carbene catalysts were also examined. Hydrogenation of an all‐ trans precursor made from (±)‐monomer using RuCl 3 as catalyst gave an atactic polymer, confirming previous observations. Hydrogenation of a 61% cis, cis/trans blocky precursor, made from (±)‐monomer using OsCl 3 /PhCCH as catalyst, gave a syndiotactic‐biased stereoblocky polymer, indicating a c/r, t/m correlation in the precursor polymer.