Hetero cyclic metallocene compounds and use thereof in catalyst system for producing olefin polymers

A ligand of formula (V):

• LG′Z′ (V)
• wherein L is a divalent group bridging the moieties G and Z, selected from CR1R2, SiR1R2 or (CR1R2)2, wherein R1 and R2, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom, and can form a ring having 3 to 8 atoms optionally bearing a substituent;
• Z′ is a moiety of formula (VI):
• or its double bond isomers;
• wherein the double bonds are in an allowed position;
• R3 and R4, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom;
• A and B are sulfur (S), oxygen (O) or CR5, wherein R5 is hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom with the proviso that if A is S or O, then B is CR5 or if B is S or O, then A is CR5, and wherein either A or B is different than CR5 and the rings containing A and B have a double bond in the allowed position;
• G′ is a moiety of formula (VII):
• or its double bond isomers;
• wherein
• R6, R7, R8 and R9, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing heteroatoms belonging to groups 13–17 of the Periodic Table of the Elements, and at least one of substituent pairs R6 and R7, and R8 and R9 can form a ring comprising from 3 to 8 atoms, optionally bearing substituents, with the proviso that R7 is different from R8 and when R7 is a tert-butyl radical, R8 is not hydrogen.

A process for the preparation of a ligand of formula (V):

• LG′Z′ (V)
• wherein
• L is a divalent group bridging the moieties G and Z, selected from CR1R2, SiR1R2 or (CR1R2)2, wherein R1 and R2, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom, and can form a ring having 3 to 8 atoms optionally bearing a substituent;
• Z′ is a moiety of formula (VI):
• or its double bond isomers;
• wherein the double bonds are in an allowed position;
• R3 and R4, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom;
• A and B are sulfur (S), oxygen (O) or CR5, wherein R5 is hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical optionally containing a heteroatom with the proviso that if A is S or O, then B is CR5 or if B is S or O, then A is CR5, and wherein either A or B is different than CR5 and the rings containing A and B have a double bond in the allowed position;
• G′ is a moiety of formula (VII):
• or its double bond isomers;
• wherein
• R6, R7, R8 and R9, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing heteroatoms belonging to groups 13–17 of the Periodic Table of the Elements, and at least one of substituent pairs R6 and R7, and R8 and R9 can form a ring comprising from 3 to 8 atoms, optionally bearing substituents, with the proviso that R7 is different from R8 and when R7 is a tert-butyl radical, R8 is not hydrogen;
• comprising the following steps:
• a) contacting a compound of the formula (VIII) with a base selected from the group consisting of metallic sodium and potassium, sodium and potassium hydroxide and an organic lithium compound, wherein the molar ratio between the compound of the formula (VIII) and said base is at least 1:1;
• wherein
• R3 and R4, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom;
• A and B are sulfur (S), oxygen (O) or CR5, wherein R5 is hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom with the proviso that if A is S or O, then B is CR5 or if B is S or O, then A is CR5, and wherein either A or B is different than CR5 the rings containing A and B have a double bond in the allowed position;
• b) contacting the obtained anionic compounds of the formula from step a) with a compound of formula (IX):
• wherein
• R1 and R2, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom, and can form a ring having 3 to 8 atoms optionally bearing a substituent;
• R6, R7, R8 and R9, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing heteroatoms belonging to groups 13–17 of the Periodic Table of the Elements, and at least one of substituent pairs R6 and R7, and R8 and R9 can form a ring comprising from 3 to 8 atoms, optionally bearing substituents, with the proviso that R7 is different from R8 and when R7 is a tert-butyl radical, R8 is not hydrogen;
• and then
• (c) treating the obtained product from step b) with a protonating agent.

A process for the preparation of a ligand of formula (V):

• LG′Z′ (V)
• wherein L is a divalent group bridging the moieties G and Z, selected from CR1R2, SiR1R2 or (CR1R2)2, wherein R1 and R2, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom, and can form a ring having 3 to 8 atoms optionally bearing a substituent;
• Z′ is a moiety of formula (VI):
• or its double bond isomers;
• wherein the double bonds are in an allowed position;
• R3 and R4, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom;
• A and B are sulfur (S), oxygen (O) or CR5, wherein R5 is hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom with the proviso that if A is S or O, then B is CR5 or if B is S or O, then A is CR5, and wherein either A or B is different than CR5 and the rings containing A and B have a double bond in the allowed position;
• G′ is a moiety of formula (VII):
• or its double bond isomers;
• wherein
• R6, R7, R8 and R9, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing heteroatoms belonging to groups 13–17 of the Periodic Table of the Elements, and at least one of substituent pairs R6 and R7, and R8 and R9 can form a ring comprising from 3 to 8 atoms, optionally bearing substituents, with the proviso that R7 is different from R8 and when R7 is a tert-butyl radical, R8 is not hydrogen;
• comprising the following steps:
• a) contacting a compound of the formula (VIII) with a base selected from the group consisting of metallic sodium and potassium, sodium and potassium hydroxide and an organic lithium compound, wherein the molar ratio between the compound of the formula (VIII) and said base is at least 1:1
• wherein
• R3 and R4, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom;
• A and B are sulfur (S), oxygen (O) or CR5, wherein R5 is hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom with the proviso that if A is S or O, then B is CR5 or if B is S or O, then A is CR5, and wherein either A or B is different than CR5 and the rings containing A and B have a double bond in the allowed position;
• b) contacting the obtained anionic compounds from step a) with a compound of formula (IX):
• wherein Y is a halogen radical selected from the group consisting of chloride, bromide and iodide;
• L is a divalent group bridging the moieties G and Z, selected from CR1R2, SiR1R2 or (CR1R2)2, wherein R1 and R2, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom, and can form a ring having 3 to 8 atoms optionally bearing a substituent;
• R6, R7, R8 and R9, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing heteroatoms belonging to groups 13–17 of the Periodic Table of the Elements, and at least one of substituent pairs R6 and R7, and R8 and R9 can form a ring comprising from 3 to 8 atoms, optionally bearing substituents, with the proviso that R7 is different from R8 and when R7 is a tert-butyl radical, R8 not hydrogen.

A process for the preparation of a metallocene compound of general formula (I):

• LGZMXp (I)
• wherein
• L is a divalent group bridging the moieties G and Z, selected from CR1R2, SiR1R2 or (CR1R2)2, wherein R1 and R2, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom, and can form a ring having 3 to 8 atoms optionally bearing a substituent;
• Z is a moiety of formula (II):
• wherein
• R3 and R4, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom;
• A and B are sulfur (S), oxygen (O) or CR5, wherein R5 is hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom with the proviso that if A is S or O, then B is CR5 or if B is S or O, then A is CR5, and wherein either A or B is different than CR5 and the rings containing A and B have a double bond in an allowed position;
• G is a moiety of formula (III):
• wherein
• R6, R7, R8 and R9, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing heteroatoms belonging to groups 13–17 of the Periodic Table of the Elements, and at least one of substituent pairs R6 and R7, and R8 and R9 can form a ring comprising from 3 to 8 atoms, optionally bearing substituents, with the proviso that R7 is different from R8 and when R7 is a tert-butyl radical, R8 is not hydrogen;
• M is an atom of a transition metal selected from those belonging to group 3, 4, 5, 6 or to the lanthanide or actinide groups in the Periodic Table of the Elements,
• X, which may be the same or different, is a hydrogen atom, halogen atom, a group R10, OR10, OSO2CF3, OCOR10, SR10, NR102 or PR102, wherein the substituents R10 are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl or C7–C20-arylalkyl radical, optionally containing heteroatoms;
• p is an integer of from 1 to 3, being equal to the oxidation state of the metal M minus 2;
• with the proviso that said metallocene compound is different from:
• isopropylidene (3-trimethylsilylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, dimethylsilanediyl (3-trimethylsilylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, isopropylidene (3-ethylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, dimethylsilanediyl (3-ethylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, isopropylidene (3-n-butylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, dimethylsilanediyl (3-n-butylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, isopropylidene (3-methylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, dimethylsilanediyl (3-methylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, isopropylidene (3-i-propylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride and dimethylsilanediyl (3-i-propylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride;
• said process comprising contacting the ligand of general formula (V)
• LG′Z′ (V)
• wherein L is a divalent group bridging the moieties G and Z, selected from CR1R2, SiR1R2 or (CR1R2)2, wherein R1 and R2, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom, and can form a ring having 3 to 8 atoms optionally bearing a substituent;
• Z′ is a moiety of formula (VI):
• or its double bond isomers;
• wherein the double bonds are in any of the allowed positions;
• R3 and R4, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom;
• A and B are sulfur (S), oxygen (O) or CR5, wherein R5 is hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom with the proviso that if A is S or O, then B is CR5 or if B is S or O, then A is CR5, and wherein either A or B is different than CR5 and the rings containing A and B have a double bond in the allowed position;
• G′ is a moiety of formula (VII):
• or its double bond isomers;
• wherein R6, R7, R8 and R9, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing heteroatoms belonging to groups 13–17 of the Periodic Table of the Elements, and at least one of substituent pairs R6 and R7, and R8 and R9 being capable of forming a ring comprising from 3 to 8 atoms, optionally having substituents, with the proviso that R7 is different from R8 and when R7 is a tert-butyl radical, R8 is not hydrogen;
• with a base capable of forming a corresponding dianionic compound and thereafter with a compound of general formula MXp+2, wherein
• M is an atom of a transition metal selected from those belonging to group 3, 4, 5, 6 or to the lanthanide or actinide groups in the Periodic Table of the Elements,
• X, which may be the same or different, is a hydrogen atom, halogen atom, a group R10, OR10, OSO2CF3, OCOR10, SR10, NR102 or PR102, wherein the substituents R10 are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing heteroatoms;
• and
• p is an integer of from 1 to 3, being equal to the oxidation state of the metal M minus 2.

A catalyst obtained by contacting:

• (A) a metallocene compound of formula (I)
• LGZMXp (I)
• wherein
• L is a divalent group bridging the moieties G and Z, selected from CR1R2, SiR1R2 or (CR1R2)2, wherein R1 and R2, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom, and can form a ring having 3 to 8 atoms optionally bearing a substituent;
• Z is a moiety of formula (II):
• wherein
• R3 and R4, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom;
• A and B are sulfur (S), oxygen (O) or CR5, wherein R5 is hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom with the proviso that if A is S or O, then B is CR5 or if B is S or O, then A is CR5, and wherein either A or B is different than CR5 and the rings containing A and B have a double bond in an allowed position;
• M is an atom of a transition metal selected from those belonging to group 3, 4, 5, 6 or to the lanthanide or actinide groups in the Periodic Table of the Elements,
• X, which may be the same or different, is a hydrogen atom, halogen atom, a group R10, OR10, OSO2CF3, OCOR10, SR10, NR102 or PR102, wherein the substituents R10 are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing heteroatoms;
• p is an integer of from 1 to 3, being equal to the oxidation state of the metal M minus 2;
• with the proviso that said metallocene compound is different from:
• isopropylidene (3-trimethylsilylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, dimethylsilanediyl (3-trimethylsilylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, isopropylidene (3-ethylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, dimethylsilanediyl (3-ethylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, isopropylidene (3-n-butylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, dimethylsilanediyl (3-n-butylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, isopropylidene (3-methylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, dimethylsilanediyl (3-methylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, isopropylidene (3-i-propylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride and dimethylsilanediyl (3-i-propylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride;
• and G is a moiety of formula (III):
• wherein R6, R7, R8 and R9, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing heteroatoms belonging to groups 13–17 of the Periodic Table of the Elements, at least one of substituent pairs R6 and R7, and R8 and R9 can form a ring comprising from 3 to 8 atoms, optionally bearing substituents;
• with the proviso that R7 is different from R8 and when R7 is a tertbutyl radical R8 is not hydrogen;
• and
• (B) at least one of an alumoxane and a compound capable of forming an alkyl metallocene.

A process for the preparation of a polymer of alpha-olefins comprising contacting one or more alpha-olefins under polymerization conditions with a catalyst obtained by contacting:

• (A) a metallocene compound of formula (I)
• LGZMXp (I)
• wherein
• L is a divalent group bridging the moieties G and Z, selected from CR1R2, SiR1R2 or (CR1R2)2, wherein R1 and R2, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom, and can form a ring having 3 to 8 atoms optionally bearing a substituent;
• Z is a moiety of formula (II):
• wherein
• R3 and R4, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom;
• A and B are sulfur (S), oxygen (O) or CR5, wherein R5 is hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing a heteroatom with the proviso that if A is S or O, then B is CR5 or if B is S or O, then A is CR5, and wherein either A or B is different than CR5 and the rings containing A and B have a double bond in an allowed position;
• M is an atom of a transition metal selected from those belonging to group 3, 4, 5, 6 or to the lanthanide or actinide groups in the Periodic Table of the Elements,
• X, which may be the same or different, is a hydrogen atom, halogen atom, a group R10, OR10, OSO2CF3, OCOR10, SR10, NR102 or PR102, wherein the substituents R10 are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing heteroatoms;
• p is an integer of from 1 to 3, being equal to the oxidation state of the metal M minus 2;
• with the proviso that said metallocene compound is different from:
• isopropylidene (3-trimethylsilylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, dimethylsilanediyl (3-trimethylsilylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, isopropylidene (3-ethylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, dimethylsilanediyl (3-ethylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, isopropylidene (3-n-butylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, dimethylsilanediyl (3-n-butylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, isopropylidene (3-methylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, dimethylsilanediyl (3-methylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride, isopropylidene (3-i-propylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride and dimethylsilanediyl (3-i-propylcyclopentadienyl)(7-cyclopentaditiophene)zirconium dichloride;
• and G is a moiety of formula (III):
• wherein R6, R7, R8 and R9, which may be the same as or different from each other, are hydrogen, a C1–C20-alkyl, C3–C20-cycloalkyl, C2–C20-alkenyl, C6–C20-aryl, C7–C20-alkylaryl, or C7–C20-arylalkyl radical, optionally containing heteroatoms belonging to groups 13–17 of the Periodic Table of the Elements, at least one of substituent pairs R6 and R7, and R8 and R9 can form a ring comprising from 3 to 8 atoms, optionally bearing substituents;
• with the proviso that R7 is different from R8 and when R7 is a tertbutyl radical R8 is not hydrogen;
• and
• (B) at least one of an alumoxane and a compound capable of forming an alkyl metallocene.