A new mechanism for the transition metal catalyzed copolymerization of conjugated dienes with olefins: The double coordination mechanism

We have focused our interest on the ethylene- butadiene copolymerizations catalyzed with Ziegler-Natta type catalysts. The catalysts used are MgCl₂ supported titanium catalysts. The main features of these copolymerizations (stereospecificity of the butadiene enchainments, multiblock structure, gel formation) cannot be rationalized on the basis of the Cossee mechanism. We propose a new model: The double coordination mechanism. It explains all the phenomena observed. Experimental confirmations will be presented in this paper.