Stereoselective living polymerization of phenylacetylene promoted by rhodium catalysts with bidentate phosphines

Polymerization of phenylacetylene to give highly stereoregular cis-transoid polyphenylacetylene is accomplished by use of [Rh(nbd)(OMe)](2) (nbd = nor bornadiene) and Ph2P(CH2)(x)PPh2 (x = 2, dppe; x = 3, dppp; x = 4, dppb). T he catalytic system employing the ligand dppb promotes formation of polymer products with low polydispersities. The polymerization is of living nature , as proved by the dependence of polymer molecular weight on conversion and on initial monomer concentration, with molecular weight distributions alwa ys maintained within a narrow range. NMR studies of the catalytic system pr ovide information on the rhodium chemistry involved, as well as useful mean s of comparison to other rhodium-phosphine catalytic systems. (C) 2001 Else vier Science B.V. All rights reserved.