Charge-transfer complexes were precipitated from benzene solutions of arene-metal-tricarbonyl (M = Cr, Mo) and a series of electron accepters. The complexes were characterised by IR spectroscopy. The charge-transfer complexes of (arene)Mo(CO)(3) with 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil) and with 2,3,5,6-tetrabromo- 1,4-benzoquinone (bromanil) were found to be very active catalysts for the polymerization of phenylacetylene, whereas the charge-transfer complexes of the same organometallic but with 2,3,5,6-tetrafluoro-1,4-benzoquinone (fluoranil), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), and tetracyanoethene (TCNE) had very little activity. The analogous chromium systems were also inactive. Theoretical calculations were carried out to examine a relationship between the stability of the charge-transfer complex and its catalytic activity. (C) 1999 Elsevier Science B.V. All rights reserved.