Charge-transfer complexes of arene-molybdenum-tricarbonyl complexes as heterogeneous metathesis catalysts for the polymerization of phenylacetylene

Charge-transfer complexes were precipitated from benzene solutions of arene -metal-tricarbonyl (M = Cr, Mo) and a series of electron accepters. The com plexes 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 v ery active catalysts for the polymerization of phenylacetylene, whereas the charge-transfer complexes of the same organometallic but with 2,3,5,6-tetr afluoro-1,4-benzoquinone (fluoranil), 2,3-dichloro-5,6-dicyano-1,4-benzoqui none (DDQ), and tetracyanoethene (TCNE) had very little activity. The analo gous chromium systems were also inactive. Theoretical calculations were car ried out to examine a relationship between the stability of the charge-tran sfer complex and its catalytic activity. (C) 1999 Elsevier Science B.V. All rights reserved.