摘要 |
A catalyst composition comprising a first component which is a substituted-bis(cyclopentadienyl) titanium, zirconium or hafnium compound, also containing a substituent which is attached to the metal and which is capable of reacting with a cation and a second component which is a compound having a bulky and labile anion which is substantially non-coordinating under the reaction conditions and a cation, wherein each of the two cyclopentadienyl radicals is differently substituted by from 1 to 5 hydrocarbon substituents, none of which is attached to the metal, the total number of substituents being from 2 to 9. |