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Abstract

Catalytic activity of the tungsten aryloxo complexes WCl₅(OAr) and WOCl₃(OAr), where Ar = 4-t-C₄H₉C₆H₄, 2,6-(t-C₄H₉)₂C₆H₃, 2,6-Cl₂C₆H₃, 2,4,6-Cl₃C₆H₂, and 2,4,6-Br₃C₆H₂ in polymerization of phenylacetylene (20 °C, monomer to catalyst molar ratio = 1 000) was studied. The activity of WCl₅(OAr) as unicomponent catalysts increases with increasing electron withdrawing character of the -OAr ligand. Addition of two equivalents of organotin cocatalysts (Me₄Sn, Bu₄Sn, Ph₄Sn, Bu₃SnH) to WCl₅(O-C₆H₂Cl₃-2,4 ,6) has only slight positive effect (slightly higher polymer yield and/or molecular weight of poly(phenylacetylene)s was achieved). However, in the case of WOCl₃(O-C₆H₃Cl₂-2, 6) catalyst, it enhances the activity considerably by eliminating the induction period. Poly(phenylacetylene)s prepared with the catalysts studied have weight-average molecular weight ranging from 100 000 to 200 000. They are trans-prevailing and have relatively low molar fraction of monomer units comprised in cyclohexadiene sequences (about 6%).