New Approach to the Polymerization of Disubstituted Acetylenes by Bulky Monophosphine-Ligated Palladium Catalysts.

Bulky monophosphine-ligated Pd complexes served as unprecedented admirable catalysts for the polymerization of a disubstituted acetylene. The moderately high polymer yields and cis content of the formed polyacetylene contrasted with those observed for traditional Mo catalyst-based polymer. These Pd catalysts are strong tools to promote the understanding of the structure-property relationships of disubstituted acetylenes.

Synthesis of end-functionalized polyacetylenes that contain polar groups by employing well-defined palladium catalysts.

A series of [(dppf)PdBr(R)]-type complexes (dppf=1,1'-bis(diphenylphosphino)ferrocene; R=p-cyanophenyl (1 a), o-hydroxymethylphenyl (1 b), and triphenylvinyl (1 c)), in combination with silver trifluoromethanesulfonate (AgOTf), were demonstrated to be active for the polymerization of monosubstituted polar acetylene monomers HC≡CCONHC(4)H(9) (2), HC≡CCO(2)C(8)H(17) (3), HC≡CCH(2)OCONHC(6)H(13) (4), HC≡CCH(2)OCO(2)C(6)H(13) (5), and HC≡CCH(CH(3))OH (6). The yields and molecular weights of the polymers depended on the combination of the Pd catalyst and monomer that was employed. Matrix-assisted laser-desorption/ionization-time of flight (MALDI-TOF) mass spectrometric analysis indicated the formation of polymers that contained the "R" and "H" groups at the chain ends.