1965 Volume 22 Issue 237 Pages 35-44
Systematic combinations of three metal carbonyls, Ni (CO) 4, Co2 (CO) 8 and Fe (CO) 5, and four aluminum compounds, AlEt3, AlEt2Cl, AlEtCl2 and AlBr3, were tested for activities and stereoregularities in butadiene polymerization.
When the above metal carbonyls are coupled with AlEt3, they yield in general butadiene oligomers and when coupled with the organoaluminum compounds containing halogen, they exhibit polymerization activities with various degree of stereoregularities. AlBr3 coupled with these metal carbonyls cause “typical” cationic polymerization except when coupled with Fe (CO) 3·C4H6 complexes. The last combination gave cis-1, 4-polybutadiene.
The stereoregularities and activities of these catalysts depend not only on the transition metals but also on the aluminum compounds and the Al/transition metal molar ratio. In the relation between the catalytic activity and the molar ratio a maximum was generally observed. The maximum ratio is again characteristic to the particular couple of the two components.
These results were interpreted in terms of the ligand field effects of aluminum compounds on the catalytic activities of transition metal complexes.
