Mechanisms of phenylacetylene polymerization by molybdenum and titanium initiators

Abstract : Polymerizing phenylacetylene, a few of whose molecules are doubly labeled by 13C's on the triple bond, gives poly(phenylacetylene) in which labels are separated by a double bond when the initiator is titanium tetrabutoxide plus triethylaluminum and by a single bond when it is molybdenum pentachloride plus tetraphenytin. This tallies with the idea that the acetylene polymeri- zations induced by derivatives of molybdenum are olefin metatheses, while those induced by derivatives of titanium are acetylene insertions. The locations of the 13C nuclei were analyzed by NMR spectroscopy. Originator supplied key words include: Polymers, Polymerization, Catalysis, Mechanism, Acetylene, Polyacetylene, and NMR spectroscopy.