Metathetical polymerisation of alkynes with (arene)M(CO)<inf>3</inf> complexes (M = Cr, Mo or W; arene = toluene, o-xylene or mesitylene) by electron-transfer-chain catalysis

In situ generated (arene)M(CO)3 complexes (M = Cr, Mo or W; arene = toluene, o-xylene or mesitylene) catalyse polymerisation of phenylacetylene to polyphenyl-acetylene when refluxed for 24 h or at ambient conditions in 2 h when electron-transfer-chain catalysis is invoked by adding 0.1-0.2 equivs. of ferricinium tetrafluoroborate salt. Of the three parent metal carbonyls, only arene derivatives of Mo(CO)6 act as good catalysts under the latter conditions. The reasons for the successful results obtained with (arene)Mo(CO)3 complexes as compared with the chromium or tungsten analogues are examined using cyclic voltammetry. © 1992.