Metallocene compounds, process for their preparation...

Details Metallocene compounds, process for their preparation... Metallocene compounds, process for their preparation...

2000-01-11

2003-02-11

Wu, David W. (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S348600, C526S160000, C526S943000

Reexamination Certificate

active

06518386

ABSTRACT:

The present invention relates to a class of bridged metallocene compounds, to the process for their preparation and to the use of these metallocenes as catalyst components for the polymerization of olefins.
Metallocene compounds with two bridged cyclopentadienyl groups are known as catalyst components for the polymerization of olefins.
For example, European Patent Application EP-A-129,368 describes a catalyst system for the polymerization of olefins which comprises a bis-cyclopentadienyl coordination complex with a transition metal, wherein the two cyclopentadienyl groups can be joined by a bridging group.
In this type of metallocene compounds the two cyclopentadienyl groups are generally bridged by divalent radicals having two or more carbon atoms, such as an ethylidene group, or with atoms other than carbon, such. as a dimethylsilanediyl group.
Metallocene compounds having two cyclopentadienyl groups bridged by a single carbon atom are also known. In particular, metallocene compounds of this type having two different cyclopentadienyl groups are known.
For example, European Patent Application EP-A-351,392 describes a catalyst which can be used for the preparation of syndiotactic polyolefins and contains a metallocene compound with two cyclopentadienyl groups linked by a bridge between them, in which one of the two cyclopentadienyl groups is substituted in a manner different from that of the other. The compound indicated as being preferred is isopropylidene(fluorenyl) (cyclopentadienyl)hafnium dichloride.
As regards metallocene compounds having two equally substituted cyclopentadienyl groups bridged by a single carbon atom, in European Patent Application EP 416,566 it is described the polymerization of propylene, carried out in liquid monomer in the presence of a catalyst consisting of (A) an alumoxane and (B) a metallocene compound in which the cyclopentadienyl rings, which can be identical or different, are linked via a bridge of the formula —R
5
CR
6
— in which R
5
and R
6
can have different meanings. The only compound given as an example is isopropylidene-bis(indenyl)zirconium dichloride. However, the thus obtainable propylene polymers have a very low molecular weight.
I. F. Urazowski et al. at the Xth Fechem Conference on Organometallic Chemistry held on Sep. 5-10, 1993 in Agia Pelagia, Crete-Greece presented metallocene complexes of Ti and Zr obtained from two dicyclopentadienyl-dimethyl-methanes, namely those having an isopropyl or tertbutyl substituent on the 3-position of each cyclopentadienyl ring. However, only mechanisms of the formation of those complexes and their structural features on the basis of X-ray analysis were discussed.
A novel class of metallocene compounds has now been found which has two identical cyclopentadienyl ligands which are linked to one another by an alkylidene bridge and which can advantageously be used as catalyst components for the polymerization of olefins.
An object of the present invention is therefore a metallocene compound of the formula (I):
wherein R
1
, R
2
, R
3
and R
4
, which can be identical or different, are hydrogen atoms or C
1
-C
20
-alkyl, C
3
-C
20
-cycloalkyl, C
2
-C
20
-alkenyl, C
6
-C
20
-aryl, C
7
-C
20
-alkylaryl or C
7
-C
2
-aryl-alkyl groups which can contain silicon or germanium atoms, R
3
being different from R
2
and from a hydrogen atom, and wherein R
1
and R
2
on the same cyclopentadienyl ring can form a ring having 5 to 8 carbon atoms;
R
5
is a hydrogen atom or a —CHR
7
R
8
group;
R
6
is a C
6
-C
20
-aryl radical or a —CHR
9
R
10
group;
R
5
and R
6
can form a ring having 3 to 8 carbon atoms which can contain hetero atoms;
R
7
, R
8
, R
9
and R
10
, which can be identical or different, are hydrogen atoms or C
1
-C
20
-alkyl, C
3
-C
20
-cycloalkyl, C
2
-C
20
-alkenyl, C
6
-C
20
-aryl, C
7
-C
20
-alkylaryl or C
7
-C
20
-arylalkyl radicals which can contain hetero atoms such as nitrogen, phosphor, oxygen or sulphur, and two R
7
, R
8
, R
9
and R
10
substituents can form a ring having 3 to 8 carbon atoms which can contain hetero atoms;
M is an atom of a transition metal selected from those belonging to group 3, 4, 5, 6 or to the lanthanide or actinide groups in the Periodic Table of the Elements (new IUPAC version);
the X substituents, which can be identical or different, are hydrogen atoms, halogen atoms or R, OR, SR, NR
2
or PR
2
groups, wherein the R substituents are C
1
-C
20
-alkyl, C
3
-C
20
-cycloalkyl, C
2
-C
20
-alkenyl, C
6
-C
20
-aryl , C
7
-C
20
-alkylaryl or C
7
-C
20
-arylalkyl radicals which can contain silicon or germanium atoms;
with the proviso that, when the R
1
, R
2
and R
4
substituents are hydrogen atoms and the R
5
and the R
6
substituents are methyl groups, then the R
3
substituents are other than an isopropropyl or tertbutyl group.
The transition metal M is preferably selected from titanium, zirconium and hafnium and, more preferably, is zirconium.
The X substituents are preferably chlorine atoms or methyl radicals.
A particularly interesting class of metallocenes according to the invention is that of the compounds of the formula (I) in which the R
2
substituents are hydrogen atoms. The R
1
substituents are preferably different from hydrogen atoms. The R
3
substituents are preferably carbon, silicon or germanium atoms substituted with three alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl groups having 1 to 10 carbon atoms. The R
4
substituents are preferably hydrogen atoms. Non-limiting examples of metallocene compounds belonging to this class are:
isopropylidene-bis(3-methyl-cyclopentadienyl)zirconium dichloride,
isopropylidene-bis(3-isopropyl-cyclopentadienyl)zirconium dichloride,
isopropylidene-bis(3-t-butyl-cyclopentadienyl)zirconium dichloride,
isopropylidene-bis(2,4-dimethyl-cyclopentadienyl)zirconium dichloride,
isopropylidene-bis(2-methyl-4-t-butyl-cyclopentadienyl)zirconium dichloride and
isopropylidene-bis(2-methyl-4-phenyl-cyclopentadienyl)zirconium dichloride.
Another particularly interesting class of metallocenes according to the invention is that of the compounds of the formula (II):
and the corresponding bis-4,5,6,7-tetrahydroindenyl compounds, wherein R
3
, R
4
, R
5
, R
6
, M and X are defined as above, and the six-carbon-atom rings of the indenyl ligands can optionally be substituted. The R
3
substituents are preferably carbon, silicon or germanium atoms substituted with three alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl groups having 1 to 10 carbon atoms. The R
4
substituents are preferably hydrogen atoms. Non-limiting examples of metallocene compounds belonging to this class are:
isopropylidene-bis(3-methyl-indenyl)zirconium dichloride,
isopropylidene-bis(3-ethyl-indenyl)zirconium dichloride,
isopropylidene-bis(3-isopropyl-indenyl)zirconium dichloride,
isopropylidene-bis(3-t-butyl-indenyl)zirconium dichloride,
isopropylidene-bis(3-trimethylsilyl-indenyl)zirconium dichloride,
isopropylidene-bis(3-trimethylgermyl-indenyl)zirconium dichloride,
isopropylidene-bis(3-t-butyl-4,5,6,7-tetrahydroindenyl)zirconium dichloride.
The metallocene compounds of the formula (I) can be prepared by a process which represents another object of the present invention and which comprises the reaction of the corresponding bis-cyclopentadienyl ligands of the formula (III):
wherein R
1
, R
2
, R
3
, R
4
, R
5
and R
6
are defined as above, and A is a suitable leaving group, with a compound of the formula MX
4
, wherein M and X are defined as above. The double bonds of the cyclopentadienyl rings in the ligands of formula (III) can be in any of the allowed positions. The ligands of the formula (III) can be prepared, for example, by the method described in the co-pending Italian Patent Application No. MI/95A/100 in the name of the same Applicant.
In the case in which at least one substituent X in the metallocene compound of the formula (I) which is to be. prepared is other than a halogen, it is necessary to substitute at least one substituent X in the metallocene obtained by at least one substituent X other than a halogen.
The reaction of substituting substituent

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