Catalyst system for the preparation of polyolefins

1. A catalyst system obtained by contacting:

A) at least one metal complex of formula (I):

wherein

M is a Group 3 to 12 transition metal or a Group 13 or 14 main group metal,

X, equal to or different from each other, is a halogen atom, a R, OR, SR, NR 2 or PR 2 group,

(i) wherein R is a linear or branched, cyclic or acyclic, C 1 -C 40 alkyl, C 2 -C 40 alkenyl, C 2 -C 40 alkynyl, C 6 -C 40 -aryl, C 7 -C 40 -alkylaryl or C 7 -C 40 -arylalkyl radical; or two X groups can be joined together to form a divalent R′ group,

(ii) wherein R′ is a C 1 -C 20 -alkylidene, C 6 -C 20 -arylidene, C 7 -C 20 -alkylarylidene, or C 7 -C 20 -arylalkylidene divalent radical optionally containing heteroatoms belonging to Groups 13-17 of the Periodic Table of the Elements;

n is the oxidation state of M;

m is the formal charge of the YLZ ligand;

L is an element of the Group 15 or 16 of the Periodic Table of the Elements;

Y is an element of the Group 15 of the Periodic Table of the Elements;

Z is an element of the Group 15 of the Periodic Table of the Elements;

R 1 , equal to or different from each other, is a divalent C 1 -C 40 hydrocarbon radical optionally containing heteroatoms belonging to Groups 13-17 of the Periodic Table of the Elements or a divalent silylidene radical containing up to 5 silicon atoms;

R 2 is absent or it is a hydrogen atom or a C 1 -C 40 hydrocarbon radical optionally containing heteroatoms belonging to Groups 13-17 of the Periodic Table of the Elements;

R 3 , equal to or different from each other, are C 1 -C 40 hydrocarbon radicals optionally containing heteroatoms belonging to Groups 13-17 of the Periodic Table of the Elements;

R 4 equal to or different from each other is absent or it is a hydrogen atom or a C 1 -C 40 hydrocarbon radical optionally containing heteroatoms belonging to Groups 13-17 of the Periodic Table of the Elements;

B) at least one iron complex of the general formula (II)

wherein

the radicals X 1 , equal to or different from each other, are hydrogen atoms, halogen atoms, R, OR, OSO 2 CF 3 , OCOR, SR, NR 2 or PR 2 groups, wherein R is a linear or branched, saturated or unsaturated C 1 -C 20 alkyl, C 3 -C 20 cycloalkyl, C 6 -C 20 aryl, C 7 -C.sub.20 alkylaryl or C 7 -C 20 arylalkyl radical, optionally containing heteroatoms belonging to Groups 13-17 of the Periodic Table of the Elements; or two X 1 can optionally form a substituted or unsubstituted butadienyl radical or a OR′O group wherein R′ is a divalent radical selected from C 1 -C 20 alkylidene, C 6 -C 40 arylidene, C 7 -C 40 alkylarylidene and C 7 -C 40 arylalkylidene radicals;

D is an uncharged donor; s is 1, 2, 3 or 4; t ranges from 0 to 4;

R 6 , equal to or different from each other, are hydrogen atoms or C 1 -C 40 hydrocarbon radicals optionally containing heteroatoms belonging to Groups 13-17 of the Periodic Table of the Elements;

R 7 , equal to or different from each other, are halogen atoms, hydrogen atoms or C 1 -C 40 hydrocarbon radicals optionally containing heteroatoms belonging to Groups 13-17 of the Periodic Table of the Elements;

R 8 , equal to or different from each other, are hydrogen atoms or C 1 -C 40 hydrocarbon radicals optionally containing heteroatoms belonging to Groups 13-17 of the Periodic Table of the Elements;

C) an alumoxane or a compound that forms an alkyl cation with complexes of formula (I) and (II).

2. The catalyst system according to claim h wherein in the compound of formula (I):

M is zirconium, titanium or hafnium;

X is a C 7 -C 40 -alkylaryl radical;

n is +4;

m is −2;

L is nitrogen;

Y is nitrogen or phosphorous;

R 1 is a group (Z(R″) 2 ) n wherein Z is a carbon or a silicon atom, n is 1 or 2 and R″ is an hydrogen atom or a C 1 -C 10 hydrocarbon radical;

R 2 is a hydrogen atom or a linear or branched, saturated or unsaturated C 1 -C 10 -alkyl radicals;

R 3 are C 7 -C 20 -alkylaryl or C 7 -C 20 -arylalkyl radicals;

R 4 is absent.

3. The catalyst system according to claim h wherein in the compound of formula (II):

X 1 is a hydrogen atom,

a halogen atom or a R group wherein R is defined as a linear or branched, cyclic or acyclic, C 1 -C 40 -alkyl, C 2 -C 40 alkenyl, C 2 -C 40 alkynyl, C 6 -C 40 -aryl, C 7 -C 40 -alkylaryl or C 7 -C 40 -arylalkyl radical; or two X groups can be joined together to form a divalent R′ group;

s is 2 or 3;

t is 0, 1 or 2;

R 6 are hydrogen atoms or C 1 -C 10 alkyl radicals;

R 7 are C 1 -C 10 -alkyl radicals;

R 8 are C 1 -C 10 -alkyl radicals.

4. The catalyst system according to claim 1 , wherein R 3 is a moiety of formula (III):

wherein

the symbol * represents the point in which the moiety of formula (III) is bound to Y or Z;

R 8 , R 9 , R 10 , R 11 and R 12 are hydrogen atoms or, C 1 -C 20 hydrocarbon radicals optionally containing heteroatoms belonging to groups 13-17 of the Periodic Table of the Elements.

5. The catalyst system according to claim 4 , wherein in the moiety of formula (III):

R 9 and R 11 are hydrogen atoms and

R 8 , R 10 and R 12 are C 1 -C 10 -alkyl radicals.

6. The catalyst system according to claim 1 , further comprising an inert carrier.

7. The catalyst system according to claim 6 , wherein the inert carrier is silica.

8. A process for polymerizing one or more alpha olefins of formula CH 2 =CHT wherein T is hydrogen or a C 1 -C 20 alkyl radical comprising the step of contacting said alpha-olefins of formula CH 2 =CHT under polymerization conditions in the presence of the catalyst system of claim 1 .

9. The process according to claim 8 , comprising copolymerizing ethylene and at least one comonomer of formula CH 2 =CHT 1 wherein T 1 is a C 1 -C 20 alkyl radical.

10. The catalyst system of claim 1 , wherein A {[(2,4,6-Me 3 C 6 H 2 )NHCH 2 CH 2 ) 2 NH}Zr(CH 2 Ph) 2 and/or B is 2,6-bis[1-(2-chlor-4,6-trimethylphenylimino)ethyl]pyridine iron(II) dichloride.

11. A composition comprising a polyolefin and the catalyst system of claim 1 .

12. The composition of claim 11 , wherein said polyolefin is polyethylene.

13. The composition of claim 11 , wherein A {[(2,4,6-Me 3 C 6 H 2 )NHCH 2 CH 2 ) 2 NH}Zr(CH 2 Ph) 2 and/or B is 2,6-bis[1-(2-chlor-4,6-trimethylphenylimino)ethyl]pyridine iron(II) dichloride.

14. The composition of claim 11 , wherein the polyolefin is the product of the (co)polymerization of one or more alpha olefins of formula CH 2 =CHT wherein T is hydrogen or a C 1 -C 20 alkyl radical with said catalyst system.