| Abstract
| - The polymerization mechanism and the structure ofpoly(phenylacetylene) synthesized usingtheRh(C⋮CC6H5)(2,5-norbornadiene)[P(C6H5)3]2initiator were investigated by solid-state NMR. The13CPake doublet of the poly(phenylacetylene) containing 5%[1,2-13C]phenylacetylene was observedbyeffectively removing the chemical shift anisotropies using a compositeinversion pulse sequence. The13C13C bond distance was determined to be1.386 Å from the spectrum, which corresponds to a doublebond length. This result clearly shows that the polymerization bythe Rh initiator progresses by thecis-insertion mechanism. The 13C isotropic chemicalshifts of the protonated and nonprotonated olefincarbons were deduced to be 131.8 and 141.4 ppm, respectively, fromdifferences between some overlappedCPMAS spectra. Two-dimensional 13C CPMAS exchangeexperiments revealed conformational inhomogeneity of the main chain and the presence of slow π-flip motion ofthe phenyl ring.
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