REACTIONS OF W(CCME(3)) (OCME(3))(3) WITH TERMINAL ALKYNES - METATHESIS AND POLYMERIZATION

Catalytic metathesis of terminal alkynes RC=CH (R = alkyl, phenyl) is performed with the carbyne complex WCCMe(3) (OCCMe(3))(3) 1. This reac tion is rapidly masked by a polymerization reaction, which is the only process occurring at low temperature, The production of deprotiometal lacyclic complexes WC(3)R(2)(OCCMe(3))(2) 2 by loss of tert-butyl alco hol from the metallacyclobutadiene intermediates is shown to be respon sible for the deactivation in metathesis. Compounds of type 2 are extr emely reactive in phenylacetylene polymerization.