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Zusammenfassung:
Catalysts for the oligomerization and polymerization of ethylene have been obtained by activating phosphinoalkyl-substituted cyclopentadienyl chromium complexes, e.g. (η1,η5-R2PC2H4C5H4)CrCl2, with methylalumoxane (MAO). DFT-calculations indicate that the observed dependence of the degree of oligomerization upon the size of the substituents (R) on the P-donor atom is a result of a steric influence on the stability of the transition state for the chain termination step.