WO1999058539A1

WO1999058539A1 - Metallocenes, ligands and olefin polymerization

Info

Publication number: WO1999058539A1
Application number: PCT/EP1999/003247
Authority: WO
Inventors: Michael J. Elder
Original assignee: Montell Technology Company B.V.
Priority date: 1998-05-08
Filing date: 1999-05-07
Publication date: 1999-11-18
Also published as: AU4141999A; CN1268951A; CA2294608A1; KR20010021604A; EP0994886A1; JP2002513428A

Abstract

A class of metallocene compounds is disclosed having the following general formula (I): Rn(Cp)(A)MLp wherein Rn is a structural bridge; Cp is a heterocyclic cyclopentadienyl group of formula (II) wherein R?1 and R2¿ are hydrogen or hydrocarbon groups; M is a transition metal of group 3, 4, 5 or 6 or to the lanthanides or the actinides in the Periodic Table or the Elements (new IUPAC version); L is a monoanionic ligand; Z is NR3 or O; X and Y are selected from (CR42)n, BR42, PR4, SiR42 or GeR42; and substituents R4 are hydrogen atoms or hydrocarbon radicals, with the proviso that both X and Y cannot be carbon atoms at the same time; A is a group selected from substituted or unsubstituted cyclopentadienyls, which may carry one or more condensed cycles, =NR5, -O-, -S- and =PR5 groups, R5 being defined as substituents R?1 and R2¿, and groups corresponding to formula (II); p is an integer from 0 to 3. These metallocene compounds are useful as catalyst components for the polymerization of olefins.

Description

METALLOCENES, LIGANDS AND OLEFIN POLYMERIZATION

FIELD OF THE INVENTION

The present invention relates to a new class of metallocene compounds, to a catalyst for the

polymerization of olefins containing them and to a polymerization process carried out in the

presence of said catalyst. The invention also relates to the corresponding ligands useful as

intermediates in the synthesis of said metallocene compounds, as well as to processes for

preparing said ligands and said metallocene compounds.

DESCRIPTION OF THE PRIOR ART

Metallocene compounds with two cyclopendadienyl groups are known as catalyst components

for the polymerization of olefins.

European Patent 0 129 368, for instance, describes a catalyst system for the polymerization of

olefins comprising (a) a bis-cyclopentadienyl coordination complex with a transition metal and

(b) an alumoxane. The two cyclopentadienyl groups can be linked by a bridging group, which

is generally a divalent radical containing one or more carbon atoms or heteroatoms.

Also known are bridged metallocene compounds wherein the cyclopentadienyl moiety is

condensed to one aromatic or non aromatic ring.

For example, European Patent Application EP 0 185 918 describes the use of

ethylenbis(4,5,6,7-tetrahydro-l-indenyl)zirconium dichloride together with a suitable

cocatalyst for the preparation of isotactic polyolefins.

Metallocenes compounds in which the cyclopentadienyl groups have heteroatom containing

substituents and catalysts containing them are also known.

1 From the European Patent Application EP-A2- 0 743 317 are known metallocene compounds

possessing a cyclopentadienyl group containing a heteroatom as part of a substituted or

condensed ring system. Illustrative examples are indenyl moieties substituted with a chinoline

or pyridine radical. These catalysts containing said metallocenes are useful for the

polymerization of olefins.

US Patent 5 489 659 relates to a class of silicon-containing metallocene compounds for the

polymerization of alpha-olefins wherein the silicon atom is part of a non aromatic ring

condensed to the cyclopentadienyl ring, such as, for example, ethylenbis(4,4-dimethyl-4,5,6,7-

tetrahydro-4-silaindenyl) zirconium dichloride.

European Patent Application EP 0 590 486 describes metallocene compounds containing a

cyclopentadienyl group having a heteroatom in the ring system for use in the preparation of

polyolefins. The only illustrative examples are bis(l-phospha-2,3,4,5-

tetramethylcyclopentadienyl) zirconium dichloride and tetrakis(2,5-dimethylpyrrol)zirconium.

International patent application PCT/EP97/6297, in the name of the same Applicant, discloses

a class of bridged and unbridged heterocyclic metallocene compounds containing a

cyclopentadienyl group to which a heteroatom containing ring is fused. The catalytic system

containing said metallocenes are useful for the polymerization of olefins.

It would be desirable to provide a novel class of metallocenes which, when used in catalysts for

the polymerization of olefins, are suitable for the preparation of polyolefins.

SUMMARY OF THE INVENTION

A novel class of metallocene compounds having a particular cyclopentadienyl ligand system

has now unexpectedly been found, which can advantageously be used as catalyst components

for the polymerization of olefins. According to a first aspect, the present invention provides a metallocene compound of formula

(I):

R_n(Cp)(A)ML_p

wherein R-, is a structural bridge;

Cp is a heterocyclic cyclopentadienyl group of formula (II):

(II)

wherein substituents R¹ and R², same or different, are hydrogen atoms, C,-C₂₀ alkyl, C₃-C₂₀

cycloalkyl, C₂-C₂₀ alkenyl, C₆-C₂₀ aryl, C₇-C₂₀ alkylaryl, or C₇-C₂₀ arylalkyl radicals, optionally

two adjacent substituents R¹ and R² can form a cycle comprising from 5 to 8 carbon atoms and,

furthermore, substituents R¹ and R² can contain silicon or germanium atoms;

Z is NR³ or O, R³ being defined as substituents R¹ and R²;

X and Y, same or different, are selected from (CR⁴ ₂)_r, BR⁴ ₂, PR⁴, SiR⁴ ₂ or GeR⁴ ₂; and

substituents R⁴, same or different, are hydrogen atoms, C,-C₂₀ alkyl, C₃-C₂₀ cycloalkyl, C₂-C₂₀

alkenyl, C₆-C₂₀ aryl, C₇-C₂₀ alkylaryl or C₇-C₂₀ arylalkyl radicals; and, furthermore, substituents

R⁴ can contain hetero atoms such as nitrogen, phosphor, oxygen, silicon or germanium atoms,

with the proviso that both X and Y can not be carbon atoms at the same time;

A is a group selected from substituted or unsubstituted cyclopentadienyls, which may carry one

or more condensed cycles, =NR⁵, -O-, -S- and =PR⁵ groups, R⁵ being defined as substituents R¹

and R², and groups corresponding to formula (II); M is a transition metal selected from those belonging to group 3, 4, 5 or 6 or to the lanthanides

or the actinides of the Periodic Table of the Elements (new IUPAC version);

the substituent L, same or different, is a monoanionic ligand, selected from the group

consisting of hydrogen, halogen, -SR⁶, R⁶, -OR⁶, -NR⁶ ₂, OCOR⁶, OSO₂CF₃ and PR⁶ ₂, wherein

the substituents R⁶, same or different, are linear or branched, saturated or unsaturated C,-C₂₀

alkyl, C₃-C₂₀ cycloalkyl, C₂-C₂₀ alkenyl, C₆-C₂₀ aryl, C₇-C₂₀ alkylaryl, or C₇-C₂₀ arylalkyl

radicals, optionally containing silicon or germanium atoms;

p is an integer from 0 to 3, p being equal to the oxidation state of the metal M minus two;

n is an integer ranging from 0 to 4; and

r is an integer ranging from 1 to 4.

According to another aspect of the present invention there is provided a new class of ligands of

formula (III):

R_n(C_P)(A)_q

wherein R, n, Cp, A, have the meanings as reported above and q is 0 when n is 0 and is 1 when

n is 1 to 4, particularly useful as intermediates in the preparation of the metallocene compounds

of formula (I).

A further aspect of the present invention is a process for the preparation of ligands R„(Cp)(A)_q

of formula (III), wherein R_, Cp, A and q have the meanings as reported above.

A still further aspect of the present invention is a process for the preparation of the metallocene

compounds of formula (I), obtainable by contacting the ligand of formula (III) R_n(Cp)(A)_q with

a compound of formula ML^, wherein M, L and p are defined as above, in the presence of a

compound capable of forming the corresponding dianionic compound of the ligand of formula

(III). Another aspect of the present invention is a catalyst for the polymerization of olefins

comprising said heterocyclic metallocene and the use thereof in the polymerization of olefins.

DETAILED DESCRIPTION OF THE INVENTION

The numbering of the substituents on the cyclopentadienyl group of formula (II), to which

reference is made in the present invention, is the following:

In the metallocene compounds of the aforementioned type, the cyclopentadienyl group of

formula (II) may be linked to an identical cyclopentadienyl group, to a cyclopentadienyl

derivate or to a heteroatom containing group, such as an amino group, by divalent radicals

containing one or more carbon atoms, such as CH₂ groups, or atoms other than carbon atoms,

such as dimethylsilanediyl groups, linking the cyclopentadienyl group in the 4 position of the

above ring system to either an identical cyclopentadienyl group, to a cyclopentadienyl derivate

or to a heteroatom containing group.

An advantageous class of heterocyclic metallocenes according to the present invention

corresponds to formula (I) wherein A is a group selected from substituted or unsubstituted

cyclopentadienyls, which may carry one or more aromatic or non-aromatic condensed cycles,

such as indenyl, fluorenyl, benzoindenyl, hydrogenated or partially hydrogenated cycles, and n

is different from 0, i.e. the two cyclopentadienyl groups are linked to each other by a bridging

divalent group. Preferably, the divalent group (QR⁷ _m)_n is selected from the group consisting of

CR⁷ ₂, SiR⁷ ₂, GeR⁷ ₂, NR⁷, PR⁷ and (CR⁷ ₂)₂ and the R⁷ groups, equal or different, are linear or branched, saturated or unsaturated C,-C₂₀ alkyl, C₃-C₂₀ cycloalkyl, C₂-C₂₀ alkenyl, C₆-C₂₀ aryl,

C₇-C₂₀ alkylaryl, or C₇-C₂₀ arylalkyl radicals optionally, when Q is C, Si or Ge, both

substituents R⁷ can form a cycle comprising from 3 to 8 atoms. More preferably, said divalent

bridge is Si(CH₃)₂, SiPh₂, CH₂, (CH₂)₂ or C(CH₃)₂.

m is 1 or 2, being 1 when Q is N or P, and being 2 when Q is C, Si or Ge; n ranges from 0 to 6

and, when n > 1, the atoms Q can be the same or different, such as, for example, in the bridges

-CH₂-Si(CH₃)₂-, -CH₂-NR²- and CH₂-PR²-.

The transition metal is preferably titanium, zirconium and hafnium, more preferably it is

zirconium.

The substituents R¹ and R² are preferably hydrogen atoms.

The substituents L are preferably halogen atoms or R⁶ groups, R⁶ being defined as reported

above. More preferably they are chlorine atoms or methyl groups.

A more advantageous class of heterocyclic metallocenes according to the present invention

corresponds to formula (I) wherein A is represented by the above formula (II), i.e., the two

cyclopentadienyl moieties of the metallocene compound of the invention are identical.

Non limitative examples of said metallocenes are:

isopropylidenebis{2-(methyl)-l,l,3,3-tetramethyl-l,2,3,3a-tetrahydrocyclopenta[c][l,2,5]

azadisilole} zirconium dichloride or dimethyl;

isopropylidenebis{2-(ethyl)-l,l,3,3-tetramethyl-l,2,3,3a-tetrahydrocyclopenta[c][l,2,5]

azadisilole} zirconium dichloride or dimethyl;

isopropylidenebis{2-(iso-propyl)-l ,1 ,3,3-tetramethyl-l ,2,3,3a-tetrahydrocyclopenta[c][l ,2,5]

azadisilolejzirconium dichloride or dimethyl; isopropylidenebis{2-(tert-butyl)-l,l,3,3,5-pentamethyl-l,2,3,3a-tetrahydrocyclopenta[c][l,2,5] azadisilole}zirconium dichloride or dimethyl;

isopropyhdenebis { 2-(ethyl)- 1,1,3,3,5 -pentamethy 1- 1 ,2 ,3 ,3 a-tetrahydrocy clopenta[c] [1,2,5]

azadisilole} zirconium dichloride or dimethyl;

isopropyhdenebis {2-(iso-propyl)-l ,1 ,3,3,5-pentamethyl-l ,2,3,3a-

tetrahydrocyclopenta[c] [1,2,5] azadisilole} zirconium dichloride or dimethyl;

isopropyhdenebis {2-(tert-butyl)- 1 , 1 ,3 -trimethyl- 1 ,2,3 ,3a-tetrahydrocyclopenta[c] [ 1 ,2,5]

azaborasilole} zirconium dichloride or dimethyl;

isopropyhdenebis { 2-(tert-butyl)- 1 , 1 ,3 -trimethyl- 1 ,2,3 ,3a-tetrahydrocyclopenta[c] [ 1 ,2,5] azaphosphasilole}zirconium dichloride or dimethyl;

isopropyhdenebis (2-(tert-butyl)- 1 ,3 -dimethyl- 1 ,2,3 ,3 a-tetrahydrocyclopenta[c] [ 1 ,2,5]

azadiborole} zirconium dichloride or dimethyl;

isopropylidenebis{2-(tert-butyl)-l,3-dimethyl-l,2,3,3a-tetrahydrocyclopenta[c][l,2,5] azadiphosphole}zirconium dichloride or dimethyl;

isopropyhdenebis { 2-(tert-butyl)- 1 , 1 ,3 ,5-tetramethyl- 1 ,2,3 ,3 a-tetrahydrocyclopenta[c] [ 1 ,2,5]

azaborasilole} zirconium dichloride or dimethyl;

isopropylidenebis{2-(tert-butyl)-l,l,3,5-tetramethyl-l,2,3,3a-tetrahydrocyclopenta[c][l,2,5] azaphosphasilole}zirconium dichloride or dimethyl;

isopropyhdenebis {2-(tert-butyl)- 1 ,3 ,5-trimethyl- 1 ,2,3 ,3 a-tetrahydrocyclopenta[c] [ 1 ,2,5]

azadiborole} zirconium dichloride or dimethyl;

azadiphosphole} zirconium dichloride or dimethyl; dimethylsilanediylbis { 2-(tert-butyl)- 1 , 1 ,3 -trimethyl- 1 ,2,3 ,3a-tetrahydrocyclopenta[c] [ 1 ,2,5]

azaborasilole} zirconium dichloride or dimethyl;

dimethylsilanediylbis {2-(tert-butyl)- 1 , 1 ,3 -trimethyl- 1 ,2,3 ,3 a-tetrahydrocyclopenta[c] [ 1 ,2,5]

azaphosphasilole} zirconium dichloride or dimethyl;

dimethylsilanediylbis{2-(tert-butyl)-l,3-dimethyl-l,2,3,3a-tetrahydrocyclopenta[c][l,2,5]

azadiborole} zirconium dichloride or dimethyl;

dimethylsilanediylbis { 2-(tert-butyl)- 1 ,3 -dimethyl- 1,2,3,3 a-tetrahydrocyclopenta[c] [1,2,5]

azadiphosphole} zirconium dichloride or dimethyl;

dimethylsilanediylbis {2-(tert-butyl)- 1 ,3 ,5-trimethyl- 1 ,2,3 ,3a-tetrahydrocyclopenta[c] [1 ,2,5] azadiborole} zirconium dichloride or dimethyl;

dimethylsilanediylbis{2-(tert-butyl)-l,3,5-trimethyl-l,2,3,3a-tetrahydrocyclopenta[c][l,2,5]

azadiphosphole} zirconium dichloride or dimethyl;

ispropylidene { 2-(tert-butyl)- 1 , 1 -dimethyl-2,3 ,4,7a-tetrahydro- 1 H-cyclopenta[c] [ 1 ,2]

azasiline} zirconium dichloride or dimethyl;

dimethylsilanediylbis { 2-(tert-butyl)- 1 , 1 -dimethyl-2,3 ,4,7a-tetrahydro- 1 H-cyclopenta[c] [ 1 ,2]

azasiline} zirconium dichloride or dimethyl;

Another interesting class of heterocyclic metallocenes according to the present invention

corresponds to formula (I), wherein A corresponds to formula (II) and n = 0, i.e., the two

identical cyclopentadienyl groups are not linked to each other by a bridging divalent group.

Non limiting examples of said class are:

{2-(tert-butyl)-l ,1 ,3,3-tetramethyl-l ,2,3,3a-tetrahydrocyclopenta[c][l ,2,5]

azadisilole} zirconium dichloride or dimethyl; {2-(tert-butyl)-l,l,3,3,5-pentamethyl-l,2,3,3a-tetrahydrocyclopenta[c][l,2,5]azadisilole}

zirconium dichloride or dimethyl;

{2-(methyl)-l,l,3,3-tetramethyl-l,2,3,3a-tetrahydrocyclopenta [c][l,2,5] azadisilole} zirconium

dichloride or dimethyl;

{2-(methyl)- 1 , 1 ,3 ,3 ,5-pentamethyl- 1 ,2,3 ,3a-tetrahydrocyclopenta[c] [ 1 ,2,5]

azadisilole} zirconium dichloride or dimethyl;

{2-(ethyl)-l,l,3,3-tetramethyl-l,2,3,3a-tetrahydrocyclopenta[c][l,2,5]azadisilole}zirconium

dichloride or dimethyl;

{2-(ethyl)-l, 1,3,3, 5-pentamethyl-l,2,3,3a-tetrahydrocyclopenta [c] [1,2,5]

azadisilole}zirconium dichloride or dimethyl;

{2-(iso-propyl)-l,l,3,3-tetramethyl-l,2,3,3a-tetrahydrocyclopenta[c][l,2,5]azadisilole}

zirconium dichloride or dimethyl;

{2-(iso-propyl)- 1 , 1 ,3,3,5-pentamethyl- 1 ,2,3 ,3a-tetrahydrocyclopenta[c] [ 1 ,2,5]azadisilole}

zirconium dichloride or dimethyl;

{2-(tert-butyl)-l,l,3-trimethyl-l,2,3,3a-tetrahydrocyclopenta [c] [1,2,5]

azaborasilole} zirconium dichloride or dimethyl;

{2-(tert-butyl)-l,l,3-trimethyl-l,2,3,3a-tetrahydrocyclopenta[c][l,2,5]azaphosphasilole}

zirconium dichloride or dimethyl;

{2-(tert-butyl)-l ,3-dimethyl-l ,2,3 ,3a-tetrahydrocyclopenta[c][l ,2,5]azadiborol}zirconium

dichloride or dimethyl;

{ 2-(tert-butyl)- 1 ,3-dimethyl- 1 ,2,3 ,3 a-tetrahydrocyclopenta [c] [ 1 ,2,5]

azadiphosphole} zirconium dichloride or dimethyl; {2-(tert-butyl)-l,l,3,5-tetramethyl-l,2,3,3a-tetrahydrocyclopenta[c][l,2,5]azaborasilole}

zirconium dichloride or dimethyl;

{2-(tert-butyl)-l , 1 ,3,5-tetramethyl- 1 ,2,3,3a-tetrahydrocyclopenta[c] [1 ,2,5]azaphosphasilole}

zirconium dichloride or dimethyl;

{2-(tert-butyl)-l,3,5-trimethyl-l,2,3,3a-tetrahydrocyclopenta[c][l,2,5]azadiborol}zirconium

dichloride or dimethyl;

{2-(tert-butyl)-l ,3,5-trimethyl-l ,2,3,3a-

tetrahydrocyclopenta[c][l,2,5]azadiphosphole}zirconium dichloride or dimethyl;

{2-(tert-butyl)- 1 , 1 -dimethyl-2,3 ,4,7a-tetrahydro- 1 H-cyclopenta[c] [ 1 ,2]azasiline } zirconium

dichloride or dimethyl;

{2-(tert-butyl)-l ,1 -dimethyl-2,3, 4,7a-tetrahydro-lH-cyclopenta[c][l ,2]azasiline}zirconium

dichloride or dimethyl;

According to another aspect of the present invention there is provided a class of ligands of

formula (III):

R_n(Cp)(A)_q (III)

wherein R„ is a structural bridge;

Cp is a heterocyclic cyclopentadienyl group of formula (IV):

(IV)

wherein R, R¹, R², X, Y and Z, n and q have the meaning as reported, A is a group selected

from substituted or unsubstituted cyclopentadienyls, which may carry one or more condensed

10 cycles, =NR^:>, -O-, -S- and =PR⁵ groups, R⁵ being defined as substituents R¹ and R², and groups

corresponding to formula (IV).

The two double bonds of the cyclopentadienyl ring of the ligands of formula (IV) can be in any

of the allowed positions.

The aforementioned compounds of formula (IV) are particularly useful as intermediate ligands

for the preparation of the heterocyclic metallocene compounds of formula (I).

An advantageous class of heterocyclic ligands according to the present invention corresponds

to formula (III) wherein A is a group selected from substituted or unsubstituted

is different from 0, i.e. the two cyclopentadienyl moieties are linked to each other by a bridging

divalent radical. As to the divalent group R„, reference is made to the above said.

A more advantageous class of heterocyclic ligands according to the present invention

corresponds to formula (III) wherein n is different from 0 and A corresponds to formula (IV).

Non-limiting examples of this class of ligands according to the invention are:

isopropyhdenebis {2-(tert-butyl)- 1 , 1 ,3 ,3-tetramethyl- 1 ,2,3 ,3 a-tetrahydrocyclopenta[c] [ 1 ,2,5]

azadisilole};

isopropyhdenebis {2-(methyl)- 1 , 1 ,3 ,3 -tetramethyl- 1 ,2,3 ,3a-tetrahydrocyclopenta[c] [ 1 ,2,5]

azadisilole};

isopropyhdenebis { 2-(ethyl)- 1 , 1 ,3 ,3-tetramethyl- 1 ,2,3 ,3 a-tetrahydrocyclopenta[c] [ 1 ,2,5]

azadisilole};

isopropylidenebis{2-(iso-propyl)-l,l,3,3-tetramethyl-l,2,3,3a-tetrahydrocyclopenta[c][l,2,5]

azadisilole};

11 isopropylidene{2-(tert-butyl)-l, 1,3,3, 5-pentamethyl-l,2,3,3a-tetrahydrocyclopenta[c][l, 2,5]

azadisilole};

isopropylidene {2-(ethyl)- 1 , 1 ,3 ,3 ,5-pentamethyl- 1 ,2,3 ,3a-tetrahydrocyclopenta[c] [1 ,2,5]

azadisilole};

isopropylidene {2-(iso-propyl)- 1 , 1 ,3,3,5-pentamethyl- 1 ,2,3,3a-tetrahydrocyclopenta[c] [1 ,2,5]

azadisilole};

isopropylidenebis{2-(tert-butyl)-l,l,3-trimethyl-l,2,3,3a-tetrahydrocyclopenta[c][l,2,5]

azaborasilole};

isopropyhdenebis {2-(tert-butyl)- 1 , 1 ,3-trimethyl- 1 ,2,3 ,3a-tetrahydrocyclopenta[c] [ 1 ,2,5]

azaphosphasilole} ;

isopropyhdenebis {2-(tert-butyl)-l ,3-dimethyl-l ,2,3 ,3a-tetrahydrocyclopenta[c][l ,2,5]

azadiborol};

isopropyhdenebis {2-(tert-butyl)-l ,3-dimethyl-l ,2,3,3a-tetrahydrocyclopenta[c][l ,2,5]

azadiphosphole};

azaborasilole};

isopropyhdenebis {2-(tert-butyl)- 1 , 1 ,3 ,5-tetramethyl- 1 ,2,3 ,3 a-tetrahydrocyclopenta[c] [ 1 ,2,5]

azaphosphasilole} ;

isopropyhdenebis {2-(tert-butyl)-l ,3,5-trimethyl-l ,2,3,3a-tetrahydrocyclopenta[c][l ,2,5]

azadiborol};

isopropyhdenebis { 2-(tert-butyl)- 1 ,3 ,5-trimethyl- 1 ,2,3 ,3a-tetrahydrocyclopenta[c] [ 1 ,2,5]

azadiphosphole};

12 dimethylsilanediylbis {2-(tert-butyl)- 1 , 1 ,3-trimethyl- 1 ,2,3 ,3a-tetrahydrocyclopenta[c] [ 1 ,2,5]

azaborasilole};

dimethylsilanediylbis { 2-(tert-butyl)- 1 , 1 ,3-trimethyl- 1 ,2,3 ,3a-tetrahydrocyclopenta[c] [ 1 ,2,5]

azaphosphasilole} ;

dimethylsilanediylbis { 2-(tert-butyl)- 1 ,3-dimethyl- 1 ,2,3 ,3 a-tetrahydrocyclopenta[c] [ 1 ,2,5]

azadiborol};

dimethylsilanediylbis {2-(tert-butyl)- 1 ,3-dimethyl- 1 ,2,3 ,3 a-tetrahydrocyclopenta[c] [ 1 ,2,5]

azadiphosphole};

dimethylsilanediylbis {2-(tert-butyl)- 1 , 1 ,3 ,5-tetramethyl- 1 ,2,3 ,3a-

tetrahydrocyclopenta[c][l,2,5] azaborasilole};

dimethylsilanediylbis{2-(tert-butyl)-l,l,3,5-tetramethyl-l,2,3,3atetrahydrocyclopenta[c][l,2,5]

azaphosphasilole} ;

azadiborol};

azadiphosphole};

isopropyhdenebis {2-(tert-butyl)- 1 , 1 -dimethyl-2,3 ,4,7a-tetrahydro- 1 H-cyclopenta[c] [ 1 ,2]

azasiline};

dimethylsilanediylbis {2-(tert-butyl)- 1 , 1 -dimethyl-2,3 ,4,7a-tetrahydro- 1 H-cyclopenta[c] [ 1 ,2]

azasiline}.

A further interesting class of ligands according to the present invention corresponds to formula

(III), wherein A corresponds to formula (IV) and n = 0, i.e., the two identical cyclopentadienyl

groups are not linked to each other by a bridging divalent residue.

13 Non limiting examples of said ligands are:

bis{2-(tert-butyl)- 1,1,3 ,3-tetramethyl- 1 ,2,3,3a-tetrahydrocyclopenta[c] [ 1 ,2,5] azadisilole} ;

bis{2-(tert-butyl)-l,l,3,3,5-pentamethyl-l,2,3,3a- tetrahydrocyclopenta[c] [1,2,5] azadisilole};

bis{2-(methyl)-l,l,3,3-tetramethyl-l,2,3,3a-tetrahydrocyclopenta [c] [1,2,5] azadisilole};

bis{2-(methyl)-l,l,3,3,5-pentamethyl-l,2,3,3a-tetrahydrocyclopenta [c] [1,2,5] azadisilole};

bis{2-(ethyl)-l,l,3,3-tetramethyl-l,2,3,3a-tetrahydrocyclopenta [c] [1,2,5] azadisilole};

bis{2-(ethyl)-l,l,3,3,5-pentamethyl-l,2,3,3a-tetrahydrocyclopenta [c] [1,2,5] azadisilole};

bis{2-(iso-propyl)-l,l,3,3-tetramethyl-l, 2,3,3a- tetrahydrocyclopenta[c] [1,2,5] azadisilole};

bis{2-(iso-propyl)-l,l ,3,3,5-pentamethyl-l ,2,3,3a-tetrahydrocyclopenta[c][l ,2,5] azadisilole} ;

bis{2-(tert-butyl)-l,l,3-trimethyl-l,2,3,3a-tetrahydrocyclopenta [c] [1,2,5] azaborasilole};

bis{2-(tert-butyl)-l,l,3-trimethyl-l,2,3,3a-tetrahydrocyclopenta [c] [1,2,5] azaphosphasilole};

bis{2-(tert-butyl)-l,3-dimethyl-l,2,3,3a-tetrahydrocyclopenta [c] [1,2,5] azadiborol};

bis{2-(tert-butyl)-l,3-dimethyl-l,2,3,3a-tetrahydrocyclopenta [c] [1,2,5] azadiphosphole};

bis{2-(tert-butyl)-l,l,3,5-tetramethyl-l,2,3,3a-tetrahydrocyclopenta[c] [1,2,5] azaborasilole}

bis {2-(tert-butyl)- 1 , 1 ,3 ,5-tetramethyl- 1 ,2,3 ,3 a-tetrahydrocyclopenta[c] [ 1 ,2,5]

azaphosphasilole} ;

bis{2-(tert-butyl)-l,3,5-trimethyl-l,2,3,3a-tetrahydrocyclopenta [c] [1,2,5] azadiborol};

bis{2-(tert-butyl)-l,3,5-trimethyl-l,2,3,3a-tetrahydrocyclopenta [c] [1,2,5] azadiphosphole}.

According to a further aspect of the present invention there is provided a process for the

preparation of ligands R„(Cp)(A)_q of formula (III), wherein R has the meaning as described

above, Cp corresponds to formula (IV), A has the meaning as reported above and both n and q

are 0, comprising the step of contacting a compound of formula (V):

14 (V)

and its double bond isomers, wherein X, R¹ and R² are defined as above and Z is nitrogen, with

a compound of general formula YZ'₂, wherein Y is defined as above and Z' is a halogen atom,

in the presence of a base, to form a compound of formula (VI)

(VI)

and its double bond isomers.

The aforementioned cyclopentadienyl derivate of formula (V) can be prepared by means of

known methods such as those as described in International Patent Application

PCT/US92/08730.

According to a still further aspect of the present invention there is provided a process for the

preparation of a ligand R_n(Cp)(A')_q of formula (Ilia), wherein R has the meaning as reported

above, n is an integer from 1 to 4 and q is 1, i.e. the two groups Cp and A' are linked by a

divalent bridge, A' is a group selected from substituted or unsubstituted cyclopentadienyls,

which may carry one or more condensed cycles, =NR⁵, -O-, -S- and =PR⁵ groups, R⁵ being

defined as substituents R¹ and R², Cp corresponds to formula (IV) and Z' is a halogen atom,

comprising the following steps:

( a ) contacting a compound of formula (V):

(V)

15 and its double bond isomers, wherein X, R¹ and R² have the meaning as reported above

and Z is nitrogen, with a compound of general formula YZ'₂, wherein Y and Z' are

defined above, in the presence of a base, to form a compound of formula (VI)

(VI)

and its double bond isomers, and

( b ) contacting with a compound able to form an anion of formula (VII)

(VII)

and thereafter with a compound of general formula (VIII)

R_nZ'₂ (VIIII)

in a molar ratio (VII)/(VIII) equal to or higher than 2, or with a compound of general

formula (IX)

Z'R„A'HR⁵ (IX)

in a molar ratio (VII)/(IX) equal to or greater than 1.

As to the structural bridge R„ in the above ligands, reference is made to the above said.

Non-limiting examples of bases used to form the above compounds of formula (VI) are

hydroxides and hydrides of alkali or earth-alkali metals, metallic sodium or potassium and

organometallic lithium compounds. Preferably, methyllithium or n-butyllithium is used.

Non-limiting examples of compounds able to form the anionic compounds of formula (VII) are

16 Non-limiting examples of compounds of general formula R_nZ'₂ (VIII) are

dimethyldichlorosilane, diphenyldichlorosilane, dimethyldichlorogermanium, 2,2-

dichloropropane and 1 ,2-dibromoethane.

The synthesis of the above bridged ligands is preferably carried out by adding a solution of an

organic lithium compound in an apolar solvent to a solution of the compound (VI) in an aprotic

polar solvent. The thus obtained solution containing the compound (VII) in the anionic form is

then added to a solution of the compound of formula R_nZ'₂ in an aprotic polar solvent. The

bridged ligand can be finally separated by conventional general known procedures.

Not limitative examples of aprotic polar solvents which can be used in the above process are

tetrahydrofurane, dimethoxyethane, diethylether, toluene and dichloromethane. Not limitative

examples of apolar solvents suitable for the above process are pentane, hexane and benzene.

During the whole process, the temperature is preferably kept between -180°C and 80°C, and

more preferably between -20°C and 40°C.

compounds of formula (I), obtainable by contacting the ligand R„(Cp)(A)_q of formula (III) as

described above, with a compound capable of forming a corresponding dianionic compound

thereof and thereafter with a compound of formula ML_p+2, wherein M, L and p have the

meanings as defined above.

The compound able to form said dianion is selected from the group consisting of hydroxides

and hydrides of alkali- and earth-alkali metals, metallic sodium and potassium, and

organometallic lithium salts, and preferably said anion is n-butyllithium.

Non-limiting examples of compounds of formula ML'_p+2 are titanium tetrachloride, zirconium

tetrachloride and hafnium tetrachloride.

17 The metallocene compounds of formula (I), when n is different from 0 and A is a

cyclopentadienyl derivate, can be prepared by first reacting the bridged ligands of formula (III),

prepared as described above, with a compound able to form a delocalized anion on the

cyclopentadienyl rings, and thereafter with a compound of formula ML^, wherein M and the

substituents L are defined as above. Non limitative examples of compounds of formula ML_p+2

are titanium tetrachloride, zirconium tetrachloride and hafnium tetrachloride.

More specifically, said bridged ligands are dissolved in an aprotic polar solvent and to the

obtained solution is added a solution of an organic lithium compound in an apolar solvent. The

thus obtained anionic form is separated, dissolved in an aprotic polar solvent and thereafter

added to a suspension of the compound ML_p+2 in an aprotic polar solvent. At the end of the

reaction, the solid product obtained is separated from the reaction mixture by techniques

commonly used in the state of the art. Non limitating examples of aprotic polar solvents

suitable for the above reported processes are tetrahydrofurane, dimethoxyethane, diethylether,

toluene and dichloromethane. Non limitating examples of apolar solvents suitable for the above

process are pentane, hexane and benzene.

more preferably between -20°C and 40°C.

The unbridged metallocene compounds of formula (I), wherein n = 0 and A corresponds to

formula (II), can be prepared by reacting the anions of the formula (VII) with a tetrahalide of

the transition metal M (i.e. ML₄), M and L having the above described meanings, said reaction

being carried out in a suitable solvent.

When at least one L substituent in the metallocene compound of formula (I) is different from

halogen, it is necessary to substitute at least one substituent L in the obtained metallocene with

18 at least another substituent different from halogen. Such a substitution reaction is carried out by

methods known in the state of the art. For example, when the substituents L are alkyl groups,

the metallocenes can be reacted with alkylmagnesium halides (Grignard reagents) or with

lithiumalkyl compounds.

more preferably between -20°C and 40°C.

The heterocyclic metallocene compounds of the present invention can conveniently be used as

catalyst components for the polymerization of olefins.

Thus, according to a still further aspect of the present invention there is provided a catalyst for

the polymerization of olefins, obtainable by contacting:

( A ) a metallocene compound of formula (I), and

( B ) an alumoxane and/or a compound capable of forming an alkyl metallocene cation.

The alumoxane used as component (B) can be obtained by reacting water with an organo-

aluminium compound of formula A1R⁸ ₃ or A1₂R⁸ ₆, where at least one R⁸ is not halogen. In this

reaction the molar ratio of Al/water is comprised between 1 : 1 and 100: 1.

The molar ratio between aluminium and the metal of the metallocene is comprised between

about 10:1 and about 20000:1, and preferably between about 100:1 and about 5000:1.

The alumoxanes used in the catalyst according to the invention are considered to be linear,

branched or cyclic compounds containing at least one group of the type:

R R9

Al-O-Al R9 ^NR9

19 wherein the R⁹ substituents, same or different, are hydrogen atoms, C,-C₂₀-alkyl, C₃-C₂₀-

cyclalkyl, C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl or C₇-C₂₀-arylalkyl, optionally containing silicon or

germanium atoms, or are a -O-Al(R⁹)₂ group and, if appropriate, some R⁹ substituents can be

halogen atoms.

In particular, alumoxanes of the formula:

R9_χ R9

Al— O— (Al-O)n— Al R9^/ R9

can be used in the case of linear compounds, wherein n is 0 or an integer from 1 to 40 and the

R⁹ substituents are defined as above, or alumoxanes of the formula:

R9

(Al — O)n

can be used in the case of cyclic compounds, wherein n is an integer from 2 to 40 and the R⁹

substituents are defined as above.

Examples of alumoxanes suitable for use according to the present invention are

methylalumoxane (MAO), isobutylalumoxane (TIBAO) and 2,4,4-trimethyl-pentylalumoxane

(TIOAO).

In the catalyst used in the process according to the invention for the preparation of polyolefins,

both the heterocyclic metallocene compound of the formula (I) and the alumoxane can be

present as the product of the reaction with an organometallic aluminium compound of the

formula A1R⁸ ₃ or Al₂R⁸ ₆,in which the R⁸ substituents, same or different, are hydrogen atoms,

halogen atoms, C,-C₂₀-alkyl, C₃-C₂₀-cyclalkyl, C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl or C₇-C₂₀-arylalkyl,

optionally containing silicon or germanium atoms.

20 Non-limiting examples of aluminium compounds of the formula A1R⁸ ₃ or A1₂R⁸ ₆ are: Al(Me)₃,

Al(Et)₃, AlH(Et)₂, Al(iBu)₃, Al(iHex)₃, Al(iOct)₃, A1(C₆H₅)₃, A1(CH₂C₆H₅)₃, Al(CH₂CMe₃)₃,

Al(CH₂SiMe₃)₃, Al(Me)₂iBu, Al(Me)₂Et, AlMe(Et)₂, AlMe(iBu)₂, Al(Me)₂iBu, Al(Me)₂Cl,

Al(Et)₂Cl, AlEtCl₂, Al₂(Et)₃Cl₃, wherein Me=methyl, Et=ethyl, iBu=isobutyl, iHex=isohexyl,

iOct=2,4,4-trimethyl-pentyl.

Among the aforementioned aluminium compounds, trimethylaluminium (TMA),

triisobutylaluminium (TIBAL) and tris(2,4,4-trimethyl-pentyl)aluminium (TIOA) are preferred.

Non limitative examples of compounds able to form a metallocene alkyl cation are compounds

of formula TJD^", wherein T^" is a Broensted acid, able to give a proton and to react irreversibly

with a substituent L of the metallocene of formula (I), and D^" is a compatible anion, which does

not coordinate, which is able to stabilize the active catalytic species which originates from the

reaction of the two compounds and which is sufficiently labile to be able to be removed from

an olefinic substrate. Preferably, the anion D^" comprises one or more boron atoms. More

preferably, the anion D^" is an anion of the formula BAr'^"^, wherein substituents Ar, the same or

different from each other, are aryl radicals such as phenyl, pentafluorophenyl,

bis(trifluoromethyl)phenyl. Particularly preferred is the tetrakis-pentafluorophenyl borate.

Furthermore, compounds of formula BAr₃ can be suitably used.

The catalysts used in the process of the present invention can be also used on inert supports.

This is obtained by depositing the metallocene (A), or the product of the reaction of the same

with the component (B), or the component (B) and thereafter the metallocene (A), on supports

such as for example silica, alumina, styrene-divinylbenzene copolymers, polyethylene or

polypropylene.

21 The solid compound so obtained, in combination with further addition of the alkyl aluminium

compound as such or pre-reacted with water, is usefully employed in gas phase polymerisation.

Catalysts of the present invention are useful in the homo- and copolymerization reaction of

olefins.

Therefore, a still further object of the present invention is a process for the polymerization of

olefins comprising the polymerization reaction of at least an olefinic monomer in the presence

of a catalyst as above described.

The catalysts of the present invention can be used in the homo-polymerisation reaction of

olefins, preferably of ethylene for the preparation of HDPE, or of a-olefins, such as propylene

and 1-butene. In ethylene polymerisation, the heterocyclic metallocenes of the invention show

good activities even when used in very low Al/Zr ratios.

Another interesting use of the catalysts according to the present invention is in the

copolymerization of ethylene with higher olefins. In particular, the catalysts of the invention

can be used for the preparation of LLDPE.

Suitable olefins to be used as comonomers comprise α-olefins of the formula CH₂=CHR¹⁰,

wherein R¹⁰ is an alkyl radical having from 1 to 10 carbon atoms, and cycloolefins. Examples

of these olefins are propylene, 1-butene, 1-pentene, 4-methyl-l-pentene, 1-hexene, 1-octene, 1-

decene, 1-dodecene, 1-tetradecene, 1-esadecene, 1-octadecene, 1-eicosene, allylcyclohexene,

cyclopentene, cyclohexene, norbornene and 4,6-dimethyl-l-heptene.

The copolymers may also contain small proportions of units deriving from polyenes, in

particular from straight or cyclic, conjugated or non conjugated dienes, such as 1,4-hexadiene,

isoprene, 1,3-butadiene, 1,5-hexadiene and 1 ,6-heptadiene.

22 The units deriving from α-olefins of formula CH₂=CHR'°, from cycloolefins and/or from

polienes are present in the copolymers preferably in amounts ranging from 1% to 20% by

mole.

The saturated elastomeric copolymers can contain ethylene units and α-olefins and/or non

conjugated diolefms able to cyclopolymerise. The unsaturated elastomeric copolymers can

contain, together with the units deriving from the polymerisation of ethylene and α-olefins,

also small proportions of unsaturated units deriving from the copolymerization of one or more

polyenes. The content of unsaturated units is preferably comprised between 0 and 5% by

weight.

Non limitative examples of suitable α-olefins comprise propylene, 1-butene and 4-methyl-l-

pentene. Suitable non conjugated diolefms able to cyclopolymerise comprise 1,5-hexadiene,

1,6-heptadiene and 2 -methyl- 1,5-hexadiene.

Non limitative examples of suitable polyenes are:

(i) polyenes able to give unsaturated units, such as:

- linear, non-conjugated dienes, such as 1 ,4-hexadiene trans, 1 ,4-hexadiene cis, 6-

methyl-l,5-heptadiene, 3,7-dimethyl-l,6-octadiene and l l-methyl-l,10-dodecadiene;

- bicyclic diolefms, such as 4,5,8,9-tetrahydroindene and 6 and 7-methyl-4,5,8,9-

tetrahydroindene;

- alkenyl or alkyliden norbornenes, such as 5-ethyliden-2-norbornene, 5-isopropyliden-

2-norbornene and exo-5-isopropenyl-2-norbornene;

- polycyclic diolefms, such as dicyclopentadiene, tricyclo-[6.2.1.0²⁷]4,9-undecadiene

and the 4-methyl derivative thereof; (ii) non-conjugated diolefms able to cyclopolymerise, such as 1.5-hexadiene, 1 ,6-

heptadiene and 2-methyl- 1,5-hexadiene;

(iii) conjugated dienes, such as butadiene and isoprene.

Another object of the present invention is a process for the polymerisation of propylene carried

out in the presence of the above described catalyst.

A further interesting use of the catalysts according to the present invention is for the

preparation of cycloolefin polymers. Monocychc and polycyclic olefin monomers can be either

homopolymerised or copolymerised, also with linear olefin monomers.

Polymerisation processes according to the present invention can be carried out in gaseous

phase or in liquid phase, optionally in the presence of an inert hydrocarbon solvent either

aromatic (such as toluene), or aliphatic (such as propane, hexane, heptane, isobutane and

cyclohexane).

The polymerisation temperature is preferably ranging from about 0°C to about 250°C. In

particular, in the processes for the preparation of HDPE and LLDPE, it is preferably comprised

between 20°C and 150°C and, more preferably between 40°C and 90°C, whereas for the

preparation of the elastomeric copolymers it is preferably comprised between 0°C and 200°C

and, more preferably between 20°C and 100°C.

The polymerization pressure is ranging from 0,5 to 100 bar, preferably from 2 to 50 bar, and

more preferably from 4 to 30 bar.

The molecular weight of the polymers can be also varied merely by varying the polymerization

temperature, the type or the concentration of the catalytic components or by using molecular

weight regulators such as, for example, hydrogen.

24 The molecular weight distribution can be varied by using mixtures of different metallocenes, or

carrying out the polymerization in several steps at different polymerization temperatures and/or

different concentrations of the molecular weight regulator.

The polymerization yields depend on the purity of the metallocene component of the catalyst.

Therefore, in order to increase the yields of polymerization, metallocenes are generally used

after a purification treatment.

The components of the catalyst can be brought into contact before the polymerization. The pre-

contact concentrations are generally between 1 and 10^"8 mol/1 for the metallocene component

(A), while they are generally between 10 and 10^"8 mol/1 for the component (B). The pre-contact

is generally effected in the presence of a hydrocarbon solvent and, if appropriate, of small

quantities of monomer. The pre-contact time is generally comprised between 1 minute and 24

hours.

The following examples are given to illustrate and not to limit the invention.

GENERAL PROCEDURES CHARACTERIZATIONS

All operations were performed under nitrogen by using conventional Schlenk-line techniques.

Solvents were distilled from blue Na-benzophenone ketyl (Et₂O), CaH₂ (CH₂C1₂) or Al Bu₃

(hydrocarbons), and stored under nitrogen. BuLi (Aldrich) was used as received.

The 'H-NMR analyses of the metallocenes were carried out on an AC200 Bruker spectrometer

(CD₂C1₂, referenced against the middle peak of the triplet of the residual CHDC1₂ at 5.35 ppm).

All NMR solvents were dried over P₂O₅ and distilled before use. Preparation of the samples

were carried out under nitrogen using standard inert atmosphere techniques.

The 'H-NMR and ¹ C-NMR analyses of the polymers were carried out on a Bruker 400 MHz

instrument. The samples were analysed as solutions in tetrachlorodideuteroethane at 130°C.

25 The intrinsic viscosity [η] (dl/g) was measured in tetralin at 135°C.

The melting point Tm (°C) and ΔH (J/g) of the polymers were measured by Differential

Scanning Calorimetry (DSC) on a Mettler apparatus, according to the following procedure:

about 10 mg of sample obtained from the polymerisation were heated to 180°C with a scanning

speed equal to 20°C/minute; the sample was kept at 180°C for 5 minutes and thereafter was

cooled with a scanning speed equal to 20°C/minute. A second scanning was then carried out

according to the same modalities as the first one. The reported values are the ones obtained in

the second scanning.

The density (g/ml) was determined by immersion of a sample of extruded copolymer in a

column with a density gradient according to the ASTM D-1505 method.

In the copolymers according to the present invention, the product of the reactivity ratios r, r₂,

wherein r, is the relative reactivity of the alpha-comonomer versus ethylene and r₂ that of

ethylene versus the alpha-comonomer.

PREPARATION OF THE LIGANDS

(N-t-butylamino)(dimethyl)(cyclopentadienyl)silane and (N-t-butylamino) (dimethyl)

(methylcyclopentadienyl) silane were prepared as described in International Patent

Application PTC/US92/08730, 1992, in the name of Nickias, P.N., Devore, D.D.

Bis(l,3-bistrimethylsilylcyclopentadienyl)zirconium dichloride was purchased from Boulder

Scientific Co., Mead Co, USA. Bis(cyclopentadienyl)zirconium dichloride was purchased

from Strem Chemicals, Inc., Newburyport, MA, USA.

Example 1

Preparation of l,l,3,3-tetramethyl-l,2,3,3a- tetrahydrocyclopenta[c] [1,2,5] azadisilole

26 (N-t-butylamino)(dimethyl)(cyclopentadienyl)silane (0.071 mol, 13.9 g) was dissolved in

THF (100 mL) and treated with BuLi (144 mmol of a 2.5 M solution in hexanes) at 0 °C.

After stirring for 16 h at room temperature, the dianion solution and a THF solution (75 mL)

of dichlorodimethylsilane (0.071 mol) were added dropwise simultaneously to a flask

containing 25 mL of THF stirring at -10 °C. The mixture was warmed to room temperature

and stirred overnight. Solvents were removed in vacuo, and the residue was extracted with

pentane. After filtration and evaporation of pentane, the extract was distilled giving 1.2 g of a

colorless liquid identified to be l,l,3,3-tetramethyl-l,2,3,3a- tetrahydrocyclopenta[c] [1,2,5]

azadisilole and isomers. 'H-NMR δ (CDC1₃) (major isomer): 6.7 (m, 3H), 5.7 (broad s, 2H),

1.3 (s, 9H), 0.2 (s, 12H). ms (m/e) (rel intensity): 251 ([PM], 12), 236 (100), 179 (4), 114

(4), 73 (7).

Example 2

Preparation of l,l,3,3,5-pentamethyl-l,2,3,3a- tetrahydrocyclopenta[c] [1,2,5] azadisilole

(N-t-butylamino)(dimethyl)(methylcyclopentadienyl)silane (0.070 mol, 14.7 g) was

dissolved in THF (199 mL) and treated with butyllithium (0.14 mol of a 2.5 M sol. in

hexanes) at -78 °C. After stirring for 16 h at room temperature, the dianion solution was

added dropwise to a solution of dichlorodimethylsilane (0.070 mol, 9.03 g) in THF (100 mL)

at -78 °C. The mixture was slowly warmed to room temperature while stirring overnight.

After evaporating the solvent, the residue was extracted with pentane, filtered, and

evaporated to an oil. The oil was distilled giving 5.0 g of a colorless liquid identified as

l,l,3,3,5-pentamethyl-l,2,3,3a- tetrahydrocyclopenta[c] [1,2,5] azadisilole and isomers. Η-

NMR δ (CDC1₃) (major isomer): 6.3 (m, 1H), 5.8 (broad s, 1H), 4.9 (broad s, 1H), 2.1 (s,

27 3H), 1.3 (s, 9H), 0.3 (broad s, 6H), 0.15 (broad s, 6H). ms (m/e) (rel intensity): 265 ([PM],

14), 250 (100), 193 (3), 135 (4), 73 (16).

Example 3

Preparation of l,l,5-trimethyl-3-phenyl-l,2,3,3a-tetrahydrocyclopenta[c] [1,2,5]

azaborasilole

(N-t-butylamino)(dimethyl)(methylcyclopentadienyl)silane (95.7 mmol, 20 g) was dissolved

in THF (120 mL) cooled at -78 °C and treated with butylhthium (2,1 eq., 201 mmol of a 2.5

M sol. in hexanes). The solution was stirred for 4 h at room temperature. At -78 °C 95.1

mmol (15.7 g) of PhBCl₂ in 20 ml of pentane were added dropwise. The mixture was slowly

warmed to room temperature and stirred overnight. After filtration and evaporating the

solvent an orange-oil was obtained. The oil was distilled giving 7.0 g of a colorless liquid

identified as the title compound, ms (m/e) (rel intensity): 295 ([PM], 80), 280 (70), 239 (30),

224 (70), 160 (100).

Example 4

Preparation of l,l,5-trimethyl-3-phenyl-l,2,3,3a-tetrahydrocyclopenta[c] [1_»2,5]

azaphosphasilole

(N-t-butylamino)(dimethyl)(methylcyclopentadienyl)silane (20 mmol, 4.17 g) was dissolved

in THF (25 mL) cooled at -78 °C and treated with butylhthium (40 mmol, 16 ml of a 2.5 M

sol. in hexanes). After the reaction was completed the solution was stirred for 1.5 h at room

temperature. In a separate 250 ml flask 2.7 ml (20 mmol) of dichlorophenylphosphine and 25

ml THF were added. At -78 °C the above dianion was added dropwise, warmed to room

temperature and stirred for 2 h. After filtration and evaporating the solvent 6.61 g of an

28 orange-oil was obtained. After washing with hexane 3.68 g of a pentane soluble oil was

obtained identified as the title compound, ms (m/e) (rel intensity): 315 ([PM], 100), 300 (40),

244 (50), 135 (30), 57 (60).

PREPARATION OF THE METALLOCENES

Example 5

Preparation of Bis(l,l,3 -tetramethyl-l,2,3-trihydrocyclopentadienyl[c][l,2,5]

azadisilole)ZrCl₂

Butylhthium (4.0 mmol of a 2.5 M sol. in hexanes) was added slowly to a solution of 1,1,3,3-

tetramethyl-1, 2,3,3a- tetrahydrocyclopenta[c] [1,2,5] azadisilole (3.8 mmol, 0.95 g) in ether

(30 mL) at -78 °C. The reaction mixture was warmed to room temperature and stirred for an

additional 3 h. Solvents were removed in vacuo and the residue was mixed with ZrCl₄ (1.9

mmol, 0.443 g) in a glove box. The mixture was slurried in pentane (40 mL)/ether (1 mL)

and stirred for 16 h. After evaporating the solvents, the residue was extracted with

dichloromethane and filtered. Evaporation of the filtrate gave 1.0 g of bis(l, 1,3,3-

tetramethyl-l,2,3,trihydrocyclopentadienyl[c][l,2,5]azadisilole)ZrCl₂,

(l,2(tBuN=(SiMe₂)₂)Cp)₂ZrCl₂. as a tan powder. 'H-NMR δ (CD₂C1₂): 6.85 (s, 2H), 6.5 (t,

1H), 1.4 (s, 9H), 0.6 (s, 6H), 0.3 (s, 6H).

29 POLYMERIZATION OF ETHYLENE

Methylalumoxane (MAO)

A commercial product commercialised by Schering was used in solution of 10% by weight in

toluene.

EXAMPLES 6 TO 9

A dry 200 mL glass autoclave equipped with magnetic stirrer, temperature probe, and feed

line for ethylene was sparged with ethylene at 35 °C. At room temperature, 90 mL of hexane

were introduced. The catalyst system was prepared separately in 10 mL of hexane by

consecutively introducing the methylalumoxane, or triisooctylaluminum/water (Al/H₂O =

2.1) mixture, and after 5 minutes stirring, the metallocene compound

(l,2(tBuN=(SiMe₂)₂)Cp)₂ZrCl₂ dissolved in minimum amount of toluene. After stirring for 5

minutes, the solution was introduced into the autoclave under ethylene flow, the reactor was

closed, the temperature was raised to 80 °C and pressurized with ethylene to 4.6 barg. The

total pressure was kept constant by feeding ethylene on demand. The polymerization was

stopped by cooling, degassing the reactor, and introducing 1 mL of methanol. The resulting

polymer was washed with acidic methanol, methanol, and dried in an oven at 60 °C under

vacuum. The results are listed in Table 1. The polymerization conditions are reported in

table 1.

Examples 10 to 11 (Comparison)

The examples were repeated according to the procedure described in the examples 6-9, but

using bis[l,3-bis(trimethylsilyl) cyclopentadienyl] zirconium dichloride instead of

Bis(l,l,3,3-tetramethyl-l,2,3, trihydrocyclopentadienyl[c][ 1,2,5] azadisilole)ZrCl₂. The

polymerization conditions are reported in table 1.

30 Examples 12 to 13 (Comparison)

using bis(cyclopentadienyl)zirconium dichloride instead of Bis(l,l,3,3-tetramethyl-l,2,3,

trihydrocyclopentadienyl[c][l,2,5] azadisilole)ZrCl₂. The polymerization conditions are

reported in table 1.

31 Table 1.

Ethylene polymerization results

Ex. metallocene, cocatalyst, Al/Zr time, Pol. Activity [η], mg (μmol) (mmol) mol. ratio min g Kg/gZr/h dL/g

6 1.00 (1.51) MAO (1.51) 1000 10 2.43 105.83 n.d.

7 0.50 (0.76) MAO (0.76) 1000 10 2.65 230.83 1.48*

8 0.16 (0.24) MAO (0.25) 1026 10 0.84 228.65 1.26

9 0.50 (0.76) TIOA-H₂O 1013 8 0.42 45.73 3.58

(0.765)

10 0.13 (0.22) MAO (0.23) 1028 15 1.34 262.68 2.05

comp.

11 0.13 (0.22) TIOA-H₂O 1073 20 0.20 29.40 n.d.

comp. (0.24)

12 0.10 (0.34) MAO (0.35) 1023 10 1.07 205.76 2.99

comp.

13 0.30 (1.03) TIOA-H₂O 997 20 traces

comp. (1.02)

n.d.=not determined

32 COPOLYMERISATION OF ETHYLENE WITH 1-HEXENE

Example 14

line for ethylene was sparged with ethylene at 35 °C. Heptane (80 mL) and 1-hexene (10 ml)

were introduced at room temperature. The catalyst system was prepared separately in 10 mL

of heptane by consecutively introducing methylalumoxane (0.33 mmol) and the metallocene

(0.2 mg) dissolved in 3 mL of toluene. After stirring for 5 minutes, the solution was

introduced into the autoclave under ethylene flow, the reactor was closed, the temperature

was raised to 70 °C and pressurized with ethylene to 4.5 barg. The total pressure was kept

constant by feeding ethylene on demand. After 10 minutes, the polymerization was stopped

by cooling, degassing the reactor, and introducing 1 mL of methanol. The resulting polymer

was washed with acidic methanol, methanol, and dried in an oven at 60 °C under vacuum.

1.2 g of polymer were recovered (activity of 261 Kg/g-Zr/h) and a value of [η] = 1.0 dL/g

was obtained, and 7.7 wt.% of 1-hexene was incorporated.

DSC analysis (2° melt); Tm=l 14°C; ΔH=142 J/g.

The ¹³C NMR analysis showed the presence of 2.72 mol% 1-hexene content, a n_E (average

ethylene sequence lenght) of 37 and value of r,=62.1, r₂=0.034, and r,xr₂=2.11.

33

Claims

1. A metallocene compound of formula (I) :

R_n(Cp)(A)ML_p

wherein R„ is a structural bridge;

Cp is a heterocyclic cyclopentadienyl group of formula (II):

(II)

wherein substituents R' and R², same or different, are hydrogen atoms, C,-C₂₀ alkyl, C₃-C₂₀

cycloalkyl, C₂-C₂₀ alkenyl, C₆-C₂₀ aryl, C₇-C₂₀ alkylaryl, or C₇-C₂₀ arylalkyl radicals,

optionally two adjacent substituents R' and R² can form a cycle comprising from 5 to 8

carbon atoms and, furthermore, substituents R' and R² can contain silicon or germanium

atoms;

Z is NR³ or O, R³ being defined as substituents R' and R²;

X and Y, same or different, are selected from (CR⁴ ₂)_r, BR⁴ ₂, PR⁴, SiR⁴ ₂ or GeR ₂; and

substituents R⁴, same or different, are hydrogen atoms, C,-C₂₀ alkyl, C₃-C₂₀ cycloalkyl, C₂-

C₂₀ alkenyl, C₆-C₂₀ aryl, C₇-C₂₀ alkylaryl or C₇-C₂₀ arylalkyl radicals; and, furthermore,

substituents R⁴ can contain hetero atoms such as nitrogen, phosphor, oxygen, silicon or

germanium atoms, with the proviso that both X and Y can not be carbon atoms at the same

time;

34 A is a group selected from substituted or unsubstituted cyclopentadienyls, which may

carry one or more condensed cycles, =NR⁵, -O-, -S- and =PR⁵ groups, R⁵ being defined as

substituents R' and R², and groups corresponding to formula (II);

M is a transition metal selected from those belonging to group 3, 4, 5 or 6 or to the

lanthanides or the actinides of the Periodic Table of the Elements (new IUPAC version);

consisting of hydrogen, halogen, -SR⁶, R⁶, -OR⁶, -NR⁶ ₂, OCOR⁶, OSO₂CF₃ and PR⁶ ₂,

wherein the substituents R⁶, same or different, are linear or branched, saturated or

unsaturated C,-C₂₀ alkyl, C₃-C₂₀ cycloalkyl, C₂-C₂₀ alkenyl, C₆-C₂₀ aryl, C₇-C₂₀ alkylaryl, or

C₇-C₂₀ arylalkyl radicals, optionally containing silicon or germanium atoms;

n is an integer ranging from 0 to 4; and

r is an integer ranging from 1 to 4.

2. The metallocene according to claim 1, characterised in that R is QR⁷ _m, Q being C, Si, Ge,

N or P, and the R⁷ groups, equal or different, are linear or branched, saturated or

C₇-C₂₀ arylalkyl radicals optionally, when Q is C, Si or Ge, both substituents R⁷ can form a

cycle comprising from 3 to 8 atoms; and

m is 1 or 2, being 1 when Q is N or P, and being 2 when Q is C, Si or Ge.

3. The metallocene according to claim 2, characterised in that (QR⁷ _m)_n is selected from the

group consisting of CR⁷ ₂, SiR⁷ ₂, GeR⁷ ₂, NR⁷, PR⁷ and (CR⁷ ₂)₂, R⁷ being defined as in claim

2.

35

4. The metallocene according to claim 3, characterised in that (QR⁷ _m)_n is selected from the

group consisting of Si(CH₃)₂, SiPh₂, CH₂, (CH₂)₂ and C(CH₃)₂.

5. The metallocene according to claim 1, wherein the transition metal is selected from

titanium, zirconium and hafnium.

6. The metallocene compound according to claim 1, wherein the substituent L is a halogen or

a substituent R⁶.

7. The metallocene compound according to claim 1, wherein substituents R' and R² are

hydrogen atoms.

8. The metallocene compound according to claim 1, wherein A corresponds to formula (II),

as defined in claim 1.

9. A ligand of formula (III) :

R„(Cp)(A)_q (III)

wherein R„ is a structural bridge;

Cp is a heterocyclic cyclopentadienyl group of formula (IV):

(IV)

and its double bond isomers, wherein substituents R' and R², same or different, are

hydrogen atoms, C,-C₂₀ alkyl, C₃-C₂₀ cycloalkyl, C₂-C₂₀ alkenyl, C₅-C₂₀ aryl, C₇-C₂₀

alkylaryl, or C₇-C₂₀ arylalkyl radicals, optionally two adjacent substituents R' and R² can

form a cycle comprising from 5 to 8 carbon atoms and, furthermore, substituents R' and R²

can contain silicon or germanium atoms;

Z is NR³ or O, R³ being defined as substituents R¹ and R²;

36 X and Y, same or different, are selected from (CR\)_r, BR⁴ ₂, PR⁴, SiR⁴ ₂ or GeR⁴ ₂; and

time;

A is a group selected from substituted or unsubstituted cyclopentadienyls, which may

substituents R' and R², and groups corresponding to formula (IV);

n is an integer ranging from 0 to 4;

q is an integer ranging from 0 to 1 ; and

r is an integer ranging from 0 to 4.

10. The ligand according to claim 9, wherein R is QR⁷ _m, Q being C, Si, Ge, N or P, and the R⁷

groups, equal or different, are linear or branched, saturated or unsaturated C,-C₂₀ alkyl, C₃-

C₂₀ cycloalkyl, C₂-C₂₀ alkenyl, C₆-C₂₀ aryl, C₇-C₂₀ alkylaryl, or C₇-C₂₀ arylalkyl radicals

optionally, when Q is C, Si or Ge, both substituents R⁷ can form a cycle comprising from 3

to 8 atoms;

m is 1 or 2, being 1 when Q is N or P, and being 2 when Q is C, Si or Ge.

11. The ligand according to claim 10, characterised in that (QR⁷ _m)_n is selected from the group

consisting of CR⁷ ₂, SiR⁷ ₂, GeR⁷ ₂, NR⁷, PR⁷ and (CR⁷ ₂)₂, R⁷ being defined as in claim 1.

12. The ligand according to claim 11, characterised in that (QR⁷ _m)_n is selected from the group

consisting of Si(CH₃)₂, SiPh₂, CH₂, (CH₂)₂ and C(CH₃)₂.

13. The ligand according to claim 9, wherein substituents R' and R² are hydrogen atoms.

37

14. The ligand according to claim 9, wherein A corresponds to formula (IV), as defined in

claim 9.

15. A process for the preparation of a ligand R„(Cp)(A)_q of formula (III), Cp and A being

defined as in claim 9, and both n and q are 0, comprising the step of contacting a

compound of formula (V):

R R²2s x rr -^X^z z

// ( (V)

and its double bond isomers, wherein X, R¹ and R² are defined as in Claim 9 and Z is

nitrogen, with a compound of general formula YZ'₂, wherein Y is defined as in claim 9

and Z' is a halogen atom, in the presence of a base, to form a compound of formula (VI)

(VI)

and its double bond isomers.

16. A process for the preparation of a ligand R_n(Cp)(A')_q of formula (Ilia), wherein R is QR⁷ _m

as defined in any of claims 10 to 12, n is an integer from 1 to 4 and q is 1, A' is a group

selected from substituted or unsubstituted cyclopentadienyls, which may carry one or more

condensed cycles, =NR⁵, -O-, -S- and =PR⁵ groups, R⁵ being defined as substituents R' and

R², Cp corresponds to formula (IV) and Z' is a halogen atom, comprising the following

steps:

(a) contacting a compound of formula (V):

38 (V)

and its double bond isomers, wherein X, R' and R² are defined as in Claim 9 and Z is

(VI)

and its double bond isomers, and

(b) contacting with a compound able to form an anion of formula (VII)

(VII)

and thereafter with a compound of general formula (VIII) R_nZ'^ in a molar ratio

(VII)/(VIII) equal to or higher than 2, or with a compound of general formula (IX)

Z^A'HR⁵, in a molar ratio (VII)/(IX) equal to or greater than 1.

17. The process according to claim 15 or 16, wherein both said base to form the compound of

formula (VI) and the compound able to form said anion of formula (VII) is selected from

the group consisting of hydroxides and hydrides of alkali- and earth-alkali metals, metallic

sodium and potassium, and organometallic lithium salts.

18. The process according to claim 17, wherein both said base to form the compound of

formula (VI) and the compound able to form said anion of formula (VII) is n-butyllithium.

39

19. The process according to claim 16, wherein the halogen atom Z' of the general formulae

(VIII) and (IX) is a chlorine atom.

20. A process for the preparation of a metallocene compound according to claim 1, obtainable

by contacting the ligand R_n(Cp)(A)_q of formula (III) according to claim 9, with a

compound capable of forming a corresponding dianionic compound thereof and thereafter

with a compound of formula ML_p+2, wherein M, L and p are defined as in claim 1.

21. A process for the preparation of a metallocene compound according to claim 20, wherein

A corresponds to formula (II).

22. The process according to claim 20, wherein the compound able to form said corresponding

dianionic compound is selected from the group consisting of hydroxides and hydrides of

alkali- and earth-alkali metals, metallic sodium and potassium, and organometallic lithium

salts.

23. The process according to claim 22, wherein the compound able to form said dianionic

compound is n-butyllithium.

24. The process according to Claim 20, wherein the compound of formula ML_p+2 is selected

from titaniumtetrachlorid, zirconiumtetrachlorid and hafniumtetrachlorid.

25. A catalyst for the polymerization of olefins, obtainable by contacting:

26. (Q)a metallocene compound of formula (I) according to any of claims 1 to 8, and

27. (R)an alumoxane and/or a compound capable of forming an alkyl metallocene cation.

28. The catalyst according to Claim 25, characterized in that said alumoxane is obtained by

contacting water with an organo-aluminium compound of formula A1R⁸ ₃ or A1₂R⁸ ₃, where

at least one R⁸ is not halogen.

40

29. The catalyst according to claim 26, wherein the molar ratio between the aluminium and

water is in the range of 1 : 1 and 100: 1.

30. The catalyst according to claim 25, characterized in that said alumoxane is selected from

MAO, TIBAO and TIOAO and said organo-aluminium compound is TIOA, TMA and/or

TIBA.

31. The catalyst according to claim 25, characterized in that the compound able to form a

metallocene alkyl cation is a compound of formula TD^", wherein T^* is a Brønsted acid,

able to give a proton and to react irreversibly with a substituent L of the metallocene of

formula (I) and D^' is a compatible anion, which does not coordinate, which is able to

stabilize the active catalytic species originating from the reaction of the two compounds,

and which is sufficiently liable to be able to be removed from an olefinic substrate.

32. The catalyst according to claim 29, characterized in that the anion D^" comprises one or

more boron atoms.

33. A process for the polymerization of olefins, said process comprising the polymerization

reaction of one ore more olefin monomers in the presence of a catalyst as claimed in any of

claims 25 to 30.

34. The process according to claim 31, wherein the olefin monomers are ethylene and/or

propylene.

41