A NOVEL LIVING COORDINATION POLYMERIZATION OF ALKOXYALLENES BY A PI-ALLYLNICKEL CATALYST

A coordination polymerization of alkoxyallenes (2a-2f) by the [eta(3)- (allyl)NiOCOCF3] (1)/PPh(3) system was carried out to obtain a polymer (3) bearing exomethylenes on the main chain. The structure of the obt ained polymer was confirmed by H-1-,C-13-NMR and IR spectra, and was r evealed to consist of two units, one bearing an exomethylene side chai n and the other an end ether side chain as a result of 1,2- and 2,3-po lymerization. In the case of methoxyallene, the ratio was estimated as 32:68. The numb er average molecular weight ((M) over bar(n)) of the resulting polymer varied linearly with increasing ratio of monomer to initiator. The molecular weight distributions ((M) over bar w/(M) over bar n) of the polymers obtained here were always approximately 1.1. T hese results may strongly support that the present polymerization proc eeds by a living mechanism. Under an inert atmosphere, the propagating end of the polymer was quite stable and could be kept without any dec rease in activity for more than a week. The proportion of 1,2- and 2,3 -polymerization was a little affected by the substituents on the alkox yallenes, as the steric bulkiness of the substituents increased the co ntent of 2,3-polymerization units.