1965 Volume 22 Issue 237 Pages 24-35
Studies on a Ziegler-type catalyst, Co2 (CO) 8-Et2AlCl, constitute a preliminary part of our systematic studies on the stereoregular polymerization of dienes.
Fundamental reaction variables of the butadiene polymerization, such as the effects of preparative procedure of the catalyst, addition order of the reaction constituents and of water content on the polymerization have been studied. The electronic and infrared absorption spectra of the catalyst and of the reaction mixture were measured and the gas analysis of the both systems also carried out.
The results suggested that the Et2AlCl coordinate to the Co metal through the chlorine and the electron deficient ethyl bridge which may be cleaved when the monomer approach to the site. Spectroscopic and polymerization studies on the “base reaction” of Co2 (CO) 8with water indicated that the important species is the carbonylate cation, [Co (CO) 4B] + (B: H2O), which is presumably more labile than the original carbonyl. Thus, one of the roles of water was interpreted.
The induction period was largely eliminated by aging the Co2 (CO) 8 with the monomer to an extent observed in the polymerization with [π-C4H6Co (CO) 2] 2 catalyst. These results together with the spectral data were interpreted to mean that π-coordination of butadiene monomer to the Co metal is involved in the catalysis and that, in order to attain the better catalytic activity, the CO ligands must be expelled as much as possible to provide labile metal complexes in the reaction system.
