Polymerization of phenylacetylene catalysed by RhTp(cod) and RhBp(cod) in ionic liquids: effect of alcohols and of tetraammonium halides

RhTp(cod) ( 1 ) and RhBp(cod) ( 2 ), almost inactive in CH 2 Cl 2 , became good catalysts of phenylacetylene polymerization in ionic liquids ([bmim]Cl, [bmim]BF 4 : bmim = 1‐butyl‐3‐methylimidazolium, [mokt]BF 4 : mokt = 1‐methyl‐3‐oktylimidazolium, [bumepy]BF 4 : 1‐butyl‐4‐methylpyridinium) and in CH 2 Cl 2 in the presence of tetraammonium halides ([R 4 N]X, R = Bu, Et; X = Cl, Br). The highest yields of polyphenylacetylene with catalyst 1 were obtained in [bmim]Cl at 65°C (64% after 2 h) and in [mokt]BF 4 at 20°C (56% after 24 h). In alcohols (CH 3 OH, (CH 3 ) 2 CHOH, (CH 3 ) 3 COH) as solvents, up to 100% of the polymer was produced. When a mixture of an ionic liquid and CH 3 OH was used as the reaction medium, the polymer yield was similar to the yield achieved in an ionic liquid only, but the molecular weight increased remarkably. Tetraammonium salts, [R 4 N]X, are co‐catalysts for 1 , and the yield of the polymer increased in the order [Et 4 N]Br < [Bu 4 N]Br < [Et 4 N]Cl < [Bu 4 N]Cl. Polymers with molecular weights from 6900 to 38 800 Da were obtained with catalyst 2 in [R 4 N]Br or [R 4 N]Cl, whereas in ionic liquids ([bmim]Cl, [bmim]BF 4 ) the corresponding molecular weights were higher, from 51 300 to 60 300 Da. Copyright © 2004 John Wiley & Sons, Ltd.