Catalysts for the polymerization of olefins

Claim 1

A catalyst for the polymerization of olefins comprising the product of the reaction between: A') a zirconocenic compound of the formula (C.sub.5 R'.sub.n H.sub.5-n)R".sub.p (C.sub.5 R'.sub.m H.sub.5-m)ZrX.sub.q in which (C 5 R' n H 5-n ) and (C 5 R' m H 5-m ) are cyclopentadienyl groups, which are the same or different from each other, and in which R' is an alkyl, alkenyl, aryl, alkylaryl or arylalkyl radical containing from 1 to 20 C-atoms, a CR 2 SiR 3 group or SiR 3 group where R is the same as R', or where two or four R' substituents of the same cyclopentadienyl group form rings having from 4 to 6 C-atoms; R" is a bivalent radical selected from the group consisting of an alkenyl group containing from 1 to 8 C-atoms, ##STR2## group where R is the same as R', said R" forming a connecting bridge between two cyclopentadienyl groups; X is hydrogen, halogen, --OH, --OZr(C 5 R' n H 5-n )(C 5 R' m H 5-m ), --OR where R is the same as R', or a hydrocarbon radical having the meaning of R'; q is 1 or 2 and when q is 1, Zr is trivalent and when q is 2, Zr is tetravalent and the X substituents are the same or different from each other; p is 0 or 1 and n, m are integers from 0 to 5; in the case where R' is a hydrocarbon radical and p=0, (n+m) is ≧5; when p=1, (n+m) is ≧3; when R' is a --SiR 3 or --CR 2 SiR 3 group (n+m) is ≧1 when p=0 or when p=1 and R" is an alkylenic group; when p=1 and R" is ##STR3## (n+m) is ≧0; B') a trialkyl-Al compound or an alkyl-Al monohydride of the formula: AlR.sub.3--z H.sub.z in which R is an alkyl, alkenyl or alkylaryl radical with 1-10 C-atoms and z=0 or 1.