CA2294608A1

CA2294608A1 - Metallocenes, ligands and olefin polymerization

Info

Publication number: CA2294608A1
Application number: CA002294608A
Authority: CA
Inventors: Michael J. Elder
Original assignee: Individual
Current assignee: Basell Technology Co BV
Priority date: 1998-05-08
Filing date: 1999-05-07
Publication date: 1999-11-18
Also published as: AU4141999A; KR20010021604A; EP0994886A1; JP2002513428A; CN1268951A; WO1999058539A1

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 R1 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 R1 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 POLYMEP~iZATION
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 I29 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 9I8 describes the use of ethylenbis(4,5,6,7-tetrahydro-1-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.
CONFIRMATION COPY
_.._..~__....~.~..~. __ . _._..._... r . . . ~_~~......~_..__ 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(1-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.

._ ..._.._.,-.."~".~......_.._,.....~.. _. T . _._.._"... _.......

According to a first aspect, the present invention provides a metallocene compound of formula (I):
Rn(Cp)(A)MLp wherein Rn is a structural bridge;
Cp is a heterocyclic cyclopentadienyl group of formula (II):

~Z
O y (II) wherein substituents R' and RZ, same or different, are hydrogen atoms, C,-Czo alkyl, C3-Czo cycloalkyl, CZ-Czo alkenyl, C6-CZO aryl, C; CZO alkylaryl, or C,-CZO arylalkyl radicals, optionally two adjacent substituents R' and RZ can form a cycle comprising from 5 to $
carbon atoms and, furthermore, substituents R' and R2 can contain silicon or germanium atoms;
Z is NR3 or O, R' being defined as substituents R' and R2;
X and Y, same or different, are selected from (CR42)n BR°v PR4, SiR4z or GeR°Z; and substituents R4, same or different, are hydrogen atoms, C,-CZO alkyl, C3-CZO
cycloalkyl, Cz-CZO f alkenyl, C6-CZO aryl, C; CZO alkylaryl or C,-CZO 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, =NRS, -O-, -S- and =PRS groups, RS being defined as substituents R' and R'-, and groups corresponding to formula (II);

_.~ . .. ...._~,_~."~"~."m,~.~...,. . T .. . _ . ._~ . ~. ,..-. _.....-.._._-.._....

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, -NRG,, OCOR6, OSOzCF3 and PR62, wherein the substituents R6, same or different, are linear or branched, saturated or unsaturated C,-CZo alkyl, C3 CZO cycloalkyl, Cz-CZO alkenyl, C6-Czo aryl, C,-CZO alkylaryl, or C;
CZO 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):
~,(CP)(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 Rn(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"{Cp)(A)q with a compound of formula ML~.z, 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:

Y (I1) Rl 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 CHz 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 (QR'm)~ is selected from the group consisting of CR'2, SiR',, GeR',, NR', PR' and (CR'2)~ and the R' groups, equal or different, are linear or . _._..._~..~_._._ ... ..._.__.._w..~~.....~....._... . ~

branched, saturated or unsaturated C'-CZO alkyl, C3-CZO cycloalkyl, C2-Czo alkenyl, C6 C,a aryl, C,-Czo alkylaryl, or C,-Czo arylalkyl radicals optionally, when Q is C, Si or Ge, both substituents R' can form a cycle comprising from 3 to 8 atoms. More preferably, said divalent bridge is Si(CH3)2, SiPhz, CHZ, (CHz)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 b and, when n > 1, the atoms Q can be the same or different, such as, for example, in the bridges -CHz-Si(CH3)2-, -CHz NRz- and CHZ-PRZ-.
The transition metal is preferably titanium, zirconium and hafnium, more preferably it is zirconium.
The substituents R' and RZ 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)-1,1,3,3-tetramethyl-1,2,3,3a-tetrahydrocyclopenta[c][1,2,5]
azadisilole}zirconium dichloride or dimethyl;
isopropylidenebis{2-(ethyl)-1,1,3,3-tetramethyl-1,2,3,3a-tetrahydrocyclopenta(c] [1,2,5]
azadisilole}zirconium dichloride or dimethyl;
isopropylidenebis { 2-(iso-propyl)-1,1,3,3-tetramethyl-1,2,3,3 a-tetrahydrocyclopenta[c] [ 1,2, 5 ]
azadisilole}zirconium dichloride or dimethyl;

isopropylidenebis {2-(tent-butyl)-1,1,3,3,5-pentamethyl-1,2,3,3a-tetrahydrocyclopenta[c] [ 1,2,5]
azadisiloie}zirconium dichloride or dimethyl;
isopropylidenebis { 2-(ethyl)-1,1,3,3, 5-pentamethyl-1,2,3,3 a-tetrahydrocyclopenta[c] [ 1,2, 5 ]
azadisilole}zirconium dichloride or dimethyl;
isopropylidenebis { 2-(iso-propyl)-1,1,3,3,5-pentamethyl-1,2,3,3a-tetrahydrocyclopenta[c][1,2,5] azadisilole}zirconium dichloride or dimethyl;
isopropylidenebis{2-(tert-butyl)-1,1,3-trimethyl-1,2,3,3a-tetrahydrocyclopenta[c][1,2,5]
azaborasilole}zirconium dichloride or dimethyl;
isopropylidenebis { 2-(tent-butyl)-1,1,3-trimethyl-1,2,3, 3 a-tetrahydrocyclopenta[c] [ 1,2,5]
azaphosphasilole}zirconium dichloride or dimethyl;
isopropylidenebis{2-(tert-butyl)-1,3-dimethyl-1,2,3,3a-tetrahydrocyclopenta[c][1,2,5]
azadiborole}zirconium dichloride or dimethyl;
isopropylidenebis{2-(tert-butyl)-1,3-dimethyl-1,2,3,3a-tetrahydrocyclopenta[c][1,2,5]
azadiphosphole}zirconium dichloride or dimethyl;
isopropylidenebis{2-(tert-butyl)-1,1,3,5-tetramethyl-1,2,3,3a-tetrahydrocyclopenta[c][1,2,5]
azaborasilole}zirconium dichloride or dimethyl;
isopropylidenebis { 2-(tert-butyl)-1,1,3, 5-tetramethyl-1,2,3,3 a-tetrahydrocyclopenta(c] ( 1,2,5]
azaphosphasiloie}zirconium dichloride or dimethyl;
isopropylidenebis { 2-(tert-butyl)-1,3, 5-trimethyl-1,2,3,3 a-tetrahydrocyclopenta[c] [ 1,2, 5]
azadiborole}zirconium dichloride or dimethyl;
isopropylidenebis {2-(tert-butyl)-1,3,5-trimethyl-1,2,3,3 a-tetrahydrocyclopenta[c] [ 1,2,5]
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)-1,3-dimethyl-1,2,3,3a-tetrahydrocyclopenta[c] [ 1,2,5]
azadiborole}zirconium dichloride or dimethyl;
dimethylsilanediylbis{2-(tert-butyl)-1,3-dimethyl-I,2,3,3a-tetrahydrocyclopenta[c] [ 1,2,5]
azadiphosphole}zirconium dichloride or dimethyl;
dimethylsilanediylbis { 2-(tent-butyl)-1,3,5-trimethyl-1,2,3,3 a-tetrahydrocyclopenta[c] [ 1,2, 5 ]
azadiborole}zirconium dichloride or dimethyl;
dimethylsilanediylbis { 2-(tert-butyl)-1,3,5-trimethyl-1,2,3,3 a-tetrahydrocyclopenta[c] [ 1,2, 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-(tent-butyl)-1,1,3,3-tetramethyl-1,2,3,3a-tetrahydrocyclopenta[c] [ 1,2,5]
azadisilole}zirconium dichloride or dimethyl;

.._._~-...-.-.._ _. . _..~.....r..._...-...,~,.~.....~._ ._ _ ~ .. .
,......,~...-...~.~.___ {2-(tert-butyl)-1,1,3,3,5-pentamethyl-1,2,3,3a-tetrahydrocyclopenta[c]
[1,2,5]azadisilole}
zirconium dichloride or dimethyl;
{2-(methyl)-1,1,3,3-tetramethyl-1,2,3,3a-tetrahydrocyclopenta [c][1,2,5]
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)-1,1,3,3-tetramethyl-1,2,3,3a-tetrahydrocyclopenta[c][1,2,5]azadisilole}zirconium dichloride or dimethyl;
{2-(ethylrl,1,3,3,5-pentamethyl-1,2,3,3a-tetrahydrocyclopenta [c] [1,2,5]
azadisilole}zirconium dichloride or dimethyl;
{ 2-(iso-propyl)-1,1,3,3-tetramethyl-1,2,3,3 a-tetrahydrocyclopenta[c] [
1,2,5]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)-1,1,3-trimethyl-1,2,3,3a-tetrahydrocyclopenta [c] [1,2,5]
azaborasilole}zirconium dichloride or dimethyl;
{2-(tert-butyl)-1,1,3-trimethyl-1,2,3,3a-tetrahydrocyclopenta[c]
[1,2,5]azaphosphasilole}
zirconium dichloride or dimethyl;
{2-(tert-butyl)-1,3-dimethyl-1,2,3,3 a-tetrahydrocyclopenta[c] [
1,2,5]azadiborol } zirconium dichloride or dimethyl;
{2-(tert-butyl)-1,3-dimethyl-1,2,3,3a-tetrahydrocyclopenta [c][1,2,5]
azadiphosphole}zirconium dichloride or dimethyl;

{2-(tert-butyl)-1,1,3,5-tetramethyl-1,2,3,3a-tetrahydrocyclopenta[c] [
I,2,5]azaborasilole}
zirconium dichloride or dimethyl;
{2-(tent-butyl)-1,1,3,5-tetramethyl-1,2,3,3a-tetrahydrocyclopenta[c][1,2,5]azaphosphasilole}
zirconium dichloride or dimethyl;
{2-(tert-butyl)-1,3,5-trimethyl-1,2,3,3a-tetrahydrocyclopenta[c][1,2,5]azadiborol}zirconium dichloride or dimethyl;
{2-(tert-butyl)-1,3,5-trimethyl-1,2,3,3a-tetrahydrocyclopenta[c][1,2,5]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)-1,I-dimethyl-2,3,4,7a-tetrahydro-1H-cyclopenta[c][1,2]azasiline}zirconium dichloride or dimethyl;
According to another aspect of the present invention there is provided a class of ligands of formula (III):
R"(Cp)(A)q (III) wherein R" is a structural bridge;
Cp is a heterocyclic cyclopentadienyl group of formula (IV):

~Z HIV) R
wherein R, R', 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 cycles, =NRj, -O-, -S- and =PRS groups, RS being defined as substituents R' and R'-, 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 cyclopentadienyls, which may carry one or more aromatic or non-aromatic condensed cycles, such as indenyl, fluorenyi, benzoindenyl, hydrogenated or partially hydrogenated cycles, and n is different from 0, i.e. the two cyclopentadienyi 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:
isopropylidenebis { 2-(tert-butyl)-1,1,3,3-tetramethyl-1,2,3,3 a-tetrahydrocyclopenta[c] [ 1,2, 5]
azadisilole};
isopropylidenebis {2-(methyl)-1,1,3,3-tetramethyl-1,2,3,3a-tetrahydrocyciopenta[cJ [ 1,2,5]
a~adisilole};
isopropylidenebis { 2-(ethyl)-1,1,3,3-tetramethyl-1,2,3,3 a-tetrahydrocyclopenta[c] [ 1,2,5]
azadisilole};
isopropylidenebis { 2-(iso-propyl)-1,1,3,3-tetramethyl-1,2,3,3 a-tetrahydrocyclopenta[c] [ 1,2, 5 azadisilole};

isopropylidene {2-(tert-butyl)-1,1,3,3,5-pentamethyl-1,2,3,3a-tetrahydrocyclopenta[cJ[ 1,2,5]
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-1,2,3,3 a-tetrahydrocyclopenta[c] [ 1,2, 5]
azadisilole};
isopropylidenebis {2-(tert-butyl)-1,1,3-trimethyl-1,2,3,3a-tetrahydrocyclopenta[c] [ 1,2,5]
azaborasilole } ;
isopropylidenebis {2-{tent-butyl)-1,1,3-trimethyl-1,2,3,3a-tetrahydrocyclopenta[c] [ 1,2,5]
azaphosphasilole};
isopropylidenebis { 2-(tert-butyl}-1,3-dimethyl-1,2,3,3a-tetrahydrocyclopenta[cJ [ 1,2,5]
azadiborol};
isopropylidenebis { 2-(tert-butyl)-1, 3-dimethyl-1,2,3,3 a-tetrahydrocyclopenta[c] [ 1,2, 5 azadiphosphole};
isopropylidenebis { 2-(tent-butyl)-1,1,3, 5-tetramethyl-1,2,3,3 a-tetrahydrocyclopenta[c] [ 1,2, 5 azaborasilole};
isopropylidenebis {2-(tert-butyl)-1,1,3,5-tetramethyl-1,2,3,3a-tetrahydrocyclopenta[c] [1,2,5]
azaphosphasilole};
isopropylidenebis { 2-(tert-butyl)-1,3,5-trimethyl-1,2,3,3a-tetrahydrocyclopenta[c] [ 1,2,5]
azadiborol};
isopropylidenebis {2-(tent-butyl)-1,3,5-trimethyl-1,2,3,3a-tetrahydrocyclopenta[c] [ 1,2,5]
azadiphosphole};

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-1,2,3,3a-tetrahydrocyclopenta[c][1,2,5]
azadiphosphole};
dimethylsilanediylbis{2-(tert-butyl)-1,1,3,5-tetramethyl-1,2,3,3a-tetrahydrocyclopenta[c][1,2,5] azaborasilole};
dimethylsilanediylbis{2-(tert-butyl)-1,1,3,5-tetramethyl-1,2,3,3atetrahydrocyclopenta[c] [1,2,5]
azaphosphasilole};
dimethylsilanediylbis{2-(tert-butyl)-1,3,5-trimethyl-1,2,3,3a-tetrahydrocyclopenta[c][1,2,5]
azadiborol};
dimethylsilanediylbis { 2-(tert-butyl)-1,3,5-trimethyl-1,2,3,3a-tetrahydrocyclopenta[c] [ 1,2,5]
azadiphosphole};
isopropylidenebis { 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.

WO 99/58539 PC'f/EP99J03247 Non limiting examples of said ligands are:
bis{2-(tent-butyl)-1,1,3,3-tetramethyl-1,2,3,3a-tetrahydrocyclopenta[c]
[1,2,5] azadisilole};
bis{2-(tent-butyl)-1,1,3,3,5-pentamethyl-1,2,3,3a- tetrahydrocyclopenta[c]
[1,2,5] azadisilole};
bis{2-(methyl)-1,1,3,3-tetramethyl-1,2,3,3a-tetrahydrocyclopenta [c] [1,2,5]
azadisilole};
bis{2-(methyl)-1,1,3,3,5-pentamethyl-1,2,3,3a-tetrahydrocyclopenta [c] [1,2,5]
azadisilole};
bis{2-(ethyl)-1,1,3,3-tetramethyl-1,2,3,3a-tetrahydrocyclopenta [c] [1,2,5]
azadisilole};
bis{2-(ethyl)-1,1,3,3,5-pentamethyl-1,2,3,3a-tetrahydrocyclopenta [c] [1,2,5]
azadisilole};
bis{2-(iso-propyl)-1,1,3,3-tetramethyl-1,2,3,3a- tetrahydrocyclopenta[c]
[1,2,5] azadisilole};
bis{2-(iso-propyl)-1,I,3,3,5-pentamethyl-1,2,3,3a-tetrahydrocyclopenta[c][1,2,5] azadisilole};
bis{2-(tent-butyl)-1,1,3-trimethyl-1,2,3,3a-tetrahydrocyclopenta [c] [1,2,5]
azaborasilole};
bis{2-(tent-butyl)-1,1,3-trimethyl-1,2,3,3a-tetrahydrocyclopenta [c] [1,2,5]
azaphosphasilole};
bis{2-{tent-butyl)-1,3-dimethyl-1,2,3,3a-tetrahydrocyclopenta [c] [1,2,5]
azadiborol};
bis{2-(tert-butyl)-1,3-dimethyl-1,2,3,3a-tetrahydrocyclopenta [c] [1,2,5]
azadiphosphole};
bis{2-(tert-butyl)-1,1,3,5-tetramethyl-1,2,3,3a-tetrahydrocyclopenta[c]
[1,2,5] azaborasilole}
bis {2-(tent-butyl)-1,1,3,5-tetramethyl-1,2,3,3 a-tetrahydrocyclopenta[c] [
1,2,5]
azaphosphasilole};
bis{2-(tent-butyl)-1,3,5-trimethyl-1,2,3,3a-tetrahydrocyclopenta [c] [1,2,5]
azadiborol};
bis{2-(tert-butyl~1,3,5-trimethyl-1,2,3,3a-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):

_...w~........~,_..........~~...~...m~....._..._.-._.~.~..-~..~~"..~,.-.w.._.~.___.. _~.. ~.....,r_._.......-.~,~..~....._.__._._. _.._~....~.

M
R
and its double bond isomers, wherein X, R' 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) X~
(VI) RI
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"(Cp)(A')q of formula (IIIa), 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, NRS, -O-, -S- and =PRS groups, RS 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):

~Z
/ ~ (~
Rl WO 99/58539 PCTlEP99/03247 and its double bond isomers, wherein X, R' and RZ have the meaning as reported above and Z is nitrogen, with a compound of general formula YZ'Z, wherein Y and Z' are defined above, in the presence of a base, to form a compound of formula (VI) R2 X ~
(VI) RI
and its double bond isomers, and ( b ) contacting with a compound able to form an anion of formula (VII) 2 (VII) RI ~ Y
and thereafter with a compound of general formula (VIII) RnZ'z (VIIII) in a molar ratio (VII)/(VIII) equal to or higher than 2, or with a compound of general formula (IX) Z'R"A'HRS (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 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 of general formula R"Z'z (VIII) are dimethyldichlorosilane, diphenyldichlorosilane, dimethyldichlorogermanium, 2,2-dichloropropane and 1,2-dibromoethane.
The synthesis of the above bridged ligands is preferably carned 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"Z'z 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.
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 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~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'~z are titanium tetrachloride, zirconium tetrachloride and hafnium tetrachloride.

._.....~....~.~..~. ~ ._.. . . ._. .....ww.~_...-.-~.w 1 .. ..~.. .._....-...~.,. -. .. ... . _.._....~. ..

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 Iigands 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~2, wherein M and the substituents L are defined as above. Non limitative examples of compounds of formula ML~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~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 tetrahydrofi>rane, dimethoxyethane, diethylether, toluene and dichloromethane. Non limitating 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.
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 WO 99/58539 PCTlEP99/03247 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.
During the whole process, the temperature is preferably kept between -180°C and 80°C, and 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, or A12R86, where at least one R8 is not halogen. In this reaction the molar ratio of Al/water is comprised between 1: l 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:
R9\ ~R9 Al-O-Al R~ \ R9 WO 99!58539 PCTlEP99l03247 wherein the R9 substituents, same or different, are hydrogen atoms, C,-Czo alkyl, C3 CZO-cyclalkyl, C6-Czo-aryl, C,-CZO alkylaryl or C,-Czo-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:

\Al-O--(A1-O)n-Aly 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:

(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 A1R83 or AlZR86,in which the R8 substituents, same or different, are hydrogen atoms, halogen atoms, C,-CZO-alkyl, C3-CZO-cyclalkyl, C6-Czo-aryl, C~ CZO alkylaryl or C,-Czo-arylalkyl, optionally containing silicon or germanium atoms.

Non-limiting examples of aluminium compounds of the formula A1R83 or A1,R86 are: Al(Me)3, Al(Et)3, AIH(Et)~, Al{iBu)3, Al(iHex)3, Al(iOct);, Al(C6H5)~, AI(CH,C6H5)3, Al(CH,CMe3)3, Al(CH,SiMe3)3, Al(Me)ZiBu, Al(Me)ZEt, AIMe(Et)z, AIMe(iBu)2, Al(Me)ZiBu, Al(Me)zCl, Al{Et)2C1, AlEtCl2, A12(Et)3C13, 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 canon are compounds of formula T'D', 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~'~q, 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.

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 a-olefins of the formula CHI=CHR'°, wherein R'° 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-1-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-i-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.

The units deriving from a-olefins of formula CHz 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 a-olefins and/or non conjugated diolefins able to cyclopolymerise. The unsaturated elastomeric copolymers can contain, together with the units deriving from the polymerisation of ethylene and a-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 a-olefins comprise propylene, 1-butene and 4-methyl-1-pentene. Suitable non conjugated diolefins 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 traps, 1,4-hexadiene cis, 6 methyl-1,5-heptadiene, 3,7-dimethyl-1,6-octadiene and 11-methyl-1,10-dodecadiene;
- bicyclic diolefins, 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-norbomene and exo-5-isopropenyl-2-norbornene;
- polycyclic diolefins, such as dicyclopentadiene, tricyclo-[6.2.1.02']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 carned 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. Monocyclic 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.

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-g 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 (EtzO), CaH2 (CHZCIz) or AliBu3 (hydrocarbons), and stored under nitrogen. BuLi (Aldrich) was used as received.
The'H-NMR analyses of the metallocenes were carried out on an AC200 Broker spectrometer (CD,CIz, referenced against the middle peak of the triplet of the residual CHDC12 at 5.35 ppm).
All NMR solvents were dried over Pz05 and distilled before use. Preparation of the samples were carried out under nitrogen using standard inert atmosphere techniques.
The 'H-NMR and "C-NMR analyses of the polymers were carned out on a Broker 400 MHz instrument. The samples were analysed as solutions in tetrachlorodideuteroethane at 130°C.

The intrinsic viscosity [rl] (dl/g) was measured in tetralin at 135°C.
The melting point Tm (°C) and DH (3/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 S
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,~rz, wherein r, is the relative reactivity of the alpha-comonomer versus ethylene and r, 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(1,3-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 1,1,3,3-tetramethyl-1,2,3,3a- tetrahydrocyclopenta[c] [1,2,5]
azadisilole .. ~. _..... ~~........~..__ ~__. . ~r.._~ .y..~..~._.__._.

(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 1,1,3,3-tetramethyl-1,2,3,3a-tetrahydrocyclopenta[c] [1,2,5]
azadisilole and isomers. 'H-NMR 8 (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 1,1,3,3,5-pentamethyl-1,2,3,3a- 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 1,1,3,3,5-pentamethyl-1,2,3,3a- tetrahydrocyclopenta[c] [1,2,5] azadisilole and isomers. 'H-NMR 8 (CDCl3) (major isomer): 6.3 (m, 1 H), 5.8 (broad s, 1 H), 4.9 (broad s, 1 H), 2.1 (s, 3H), 1.3 (s, 9H), 0.3 (broad s, 6H), 0.1 S (broad s, 6H). ms (m/e) {rel intensity): 265 ([PM], 14), 250 (100), 193 (3), 135 (4), 73 (16).
Example 3 Preparation of 1,1,5-trimethyl-3-phenyl-1,2,3,3a-tetrahydrocyclopenta[c][1,2,5]
azaborasilole (N-t-butylamino){dimethyl)(methylcyclopentadienyl)silane (95.7 rnmol, 20 g) was dissolved in THF (120 mL) cooled at -78 °C and treated with butyllithium (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 1,1,5-trimethyl-3-phenyl-1,2,3,3a-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 butyllithium (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 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(1,1,3,3-tetramethyl-1,2,3-trihydrocyclopentadienyl[c][1,2,5]
azadisilole)ZrCh Butyllithium (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(1,1,3,3-tetramethyl-1,2,3,trihydrocyclopentadienyl[c][1,2,5]azadisilole)ZrCl2, {1,2(tBuN=(SiMe2)2)Cp)zZrCl2. as a tan powder. 'H-NMR S (CDZCIz): 6.85 (s, 2H), 6.5 (t, 1H), 1.4 (s, 9H), 0.6 (s, 6H), 0.3 (s, 6H).

POLYMERIZATION OF ETHYLENE
Methylalumoxane (MAO) A commercial product commercialised by Schering was used in solution of 10% by weight in toluene.

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/H20 =
2.1 ) mixture, and after 5 minutes stirring, the metallocene compound (1,2(tBuN=(SiMe2)2)Cp)zZrCl2 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 bang. 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[1,3-bis(trimethylsilyl) cyclopentadienylJ zirconium dichloride instead of Bis(1,1,3,3-tetramethyl-1,2,3, trihydrocyclopentadienyl[c][1,2,5]
azadisilole)ZrCI,. The polymerization conditions are reported in table 1.

Examples 12 to 13 (Comparison) The examples were repeated according to the procedure described in the examples 6-9, but using bis(cyclopentadienyl)zirconium dichloride instead of Bis(1,1,3,3-tetramethyl-1,2,3, trihydrocyclopentadienyl[c][1,2,5] azadisilole)ZrCh. The polymerization conditions are reported in table 1.

Table 1.
Ethylene polymerization results Ex. metallocene, cocatalyst, AUZr time, Pol. Activity [ri], mg (~mo!) (mmol) mol. ratio min g Kg/gZr/h dL/g 6 1.00 ( MAO ( 1.51 1000 10 2.43 1 O5. n.
1. S ) 83 d.
1 ) 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-HZO 1013 8 0.42 45.73 3.58 (0.765) 0.13 (0.22)MAO (0.23) 1028 15 1.34 262.68 2.05 comp.

11 0.13 (0.22)TIOA-H20 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-H20 997 20 traces comp. ( 1.02) n.d =not determined Example 14 A dry 200 mL glass autoclave equipped with magnetic stirrer, temperature probe, and feed 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 [rl] = 1.0 dL/g was obtained, and 7.7 wt.% of 1-hexene was incorporated.
DSC analysis (2° melt); Tm=114°C; DH=142 J/g.
The '3C NMR analysis showed the presence of 2.72 mol% 1-hexene content, a nE
(average ethylene sequence lenght) of 37 and value of r,=62.1, r2 0.034, and r,xr2 2.11.

Claims

1. A metallocene compound of formula (I):
R n(Cp)(A)ML p wherein R n is a structural bridge;
Cp is a heterocyclic cyclopentadienyl group of formula (II):
wherein substituents R1 and R2, same or different, are hydrogen atoms, C1-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, C1-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 C1-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.

2. The metallocene according to claim 1, characterised in that R is QR7m, Q
being C, Si, Ge, N or P, and the R7 groups, equal or different, are linear or branched, saturated or unsaturated C1-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; 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 (QR7m)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.

4. The metallocene according to claim 3, characterised in that (QR7m)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 R1 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 n(Cp)(A)q (III) wherein R n is a structural bridge;
Cp is a heterocyclic cyclopentadienyl group of formula (IV):
and its double bond isomers, wherein substituents R1 and R2, same or different, are hydrogen atoms, C1-C20 alkyl, C3-C20 cycloalkyl, C2-C20 alkenyl, C6-C20 aryl, 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, C1-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 (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 QR7m, Q being C, Si, Ge, N
or P, and the R7 groups, equal or different, are linear or branched, saturated or unsaturated C1-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 (QR7m)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 (QR7m)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 R1 and R2 are hydrogen atoms.

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 n(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):
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) and its double bond isomers.

16. A process for the preparation of a ligand R n(Cp)(A')q of formula (IIIa), wherein R is QR7m 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 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):

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) and its double bond isomers, and (b) contacting with a compound able to form an anion of formula (VII) and thereafter with a compound of general formula (VIII) R nZ'2, in a molar ratio (VII)/(VIII) equal to or higher than 2, or with a compound of general formula (IX) Z'R nA'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.

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 AlR8 3 or Al2R8 3, where at least one R8 is not halogen.

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 T+D-, wherein T+ is a Br~nsted 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.