Catalyst system for the Ziegler-Natta polymerization of olefins

A catalyst system comprising

• a) at least one aluminium alkyl complex of the formula (I)
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• where
• X1 is NH, NH2*, NH—A*, NH—SiA3*, N—A, NSiA3, N(A)2*, N(SiA3)2*, O, OSiA2, OA*, OSiA3*, OAryl*, S, SSiA2, SA*, SSiA3*, PA, PSiA3, P(A)2*, P(SiA3)2* or a single bond,
• X2 is NH, N—A, NSiA3, O, OSiA2, S, SSiA2, PA or X1 coordinated to Al(R1)3, or a single bond,
• R1 is H;
• Hal when n=0;
• A, optionally covalently bound to Al;
• Si(A)3 when X1═O,
• R2 is A, if desired covalently bound to Al;
• CH2—CH═CH, CH2—C≡C when Z1═H;
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• R3 and R4 are each, independently of one another, a bond or R2 or Si(A)3 or Si(A)2,
• Z1 is a bond or H bound to R2,
• Z2 is a bond or H bound to R2 and R3,
• where
• A is branched or unbranched C1-C7-alkyl, -alkylidene or -alkenylidene,
• Aryl is phenyl, naphthyl, indenyl, fluorenyl,
• Hal is F, Cl, and, independently of one another,
• n is 0 or 1,
• m is 0 or 1,
• p is 0 or 1,
• q is 1 or 2,
• l is 0 or 1,
• where coordinate bonds can exist between X1, X2 and Al, and R1, R2, R3, R4, X1, X2, Z1 and Z2 can, in each case independently of one another at different positions in the molecule, assume all meanings and X1 can assume only the meanings denoted by “*” when 1=0 and R1, R2, R3 or R4 are not present,
• b) magnesium chloride, SiO2 or SiO2 in combination with MgCl2 as support material,
• c) at least one catalyst selected from the group consisting of titanium halides and vanadium halides and
• d) at least one internal and, optionally, also one or more external donors selected from the group consisting of monoesters or diesters or the group consisting of compounds RSi(OR)3 or R2Si(OR)2, where R are each, independently of one another, a branched or unbranched C1-C10-alkyl group.