ABSTRACT
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. IR spectroscopic analysis supported the R-end-functionalization of the polymers. NMR spectroscopy and MS identified the presence of species that were formed by single, double, and triple insertion of the monomers into the Pd-C(6)H(4)-p-CN bond, thereby giving solid evidence for an insertion mechanism for the present system. Density functional theory (DFT) calculations suggested the preference for 1,2-insertion of the monomer compared to 2,1-insertion.
