Metallocene complexes

Details Metallocene complexes Metallocene complexes

2001-06-14

2004-06-29

Nazario-Gonzalez, Porfirio (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heavy metal containing

C556S027000, C556S053000, C502S103000, C502S117000, C502S155000, C526S132000, C526S139000, C526S161000, C526S172000, C526S943000

Reexamination Certificate

active

06756505

ABSTRACT:

The present invention relates to metallocene complexes of metals of transition group IV, V or VI of the Periodic Table, in which at least one substituted or unsubstituted cyclopentadienyl radical is bound to an element of group III of the Periodic Table which is in turn a constituent of a bridge between this cyclopentadienyl radical and the metal atom and bears an organonitrogen, organophosphorus or organosulfur group as sole further substituent.
Metallocene catalysts are gaining increasing importance in the polymerization of &agr;-olefins. Metallocene catalysts are particularly advantageous for the copolymerization of ethylene with higher &agr;-olefins since they result in particularly uniform incorporation of comonomer into the copolymer. Among metallocene catalysts, bridged metallocene complexes have attracted particular interest since they generally give a higher productivity than do the unbridged complexes, result in particularly good incorporation of comonomer and are also, for example, suitable for preparing highly isotactic polypropylene.
Bridge metallocene complexes in which the cyclopentadienyl radicals are joined by SiMe
2
or C
2
H
4
bridges have been known for a long time. Such metallocene compounds are described, for example, in EP-A-336 128.
Apart from metallocene complexes in which the cyclopentadienyl radicals are bridged via silicon or carbon atoms, bridged metallocenes in which one or more boron atoms perform the bridging function are also known. Thus, for example, boron-bridged metallocene complexes in which the boron atom bears an alkyl or aryl substituent are known (J. Organomet. Chem., 1997, 536-537, 361). However, the preparation of these metallocene complexes is very complicated; nothing is known about polymerizations using these complexes.
DE-19 539 650 likewise describes bridged metallocene complexes in which boron, inter alia, may be present as bridge member. The boron atoms having a bridging function may be substituted by various radicals such as alkyl, aryl, benzyl and halogens and also by alkoxy or hydroxy groups. Once again, nothing is known about the polymerization behavior of such metallocene complexes.
Organometallics, 1997, 16, 4546, describes boron-bridged metallocenes in which the bridging boron atom is substituted by a vinyl group and is additionally coordinated by a Lewis base. However, the yields in the synthesis of these complexes are very poor and the polymerization of ethylene proceeds unsatisfactorily and leads only to low molecular weight polymer.
EP-A-0 628 566 describes bridged metallocene complexes whose generic formula nominates carbon, silicon, tin, germanium, aluminum, nitrogen, phosphorus and also boron as bridging atoms and in which the bridging atoms may be substituted by many substituents among which the dialkylamino group is mentioned. However, metallocene complexes having an amino-substituted boron bridge are not explicitly mentioned at any point, nor are properties of such complexes described.
The boron-bridged metallocene complexes known from the prior art are mostly difficult to prepare and do not offer, of offer only to a very restricted extent, the opportunity of influencing the electronic conditions in the cyclopentadienyl groups by means of electron-donating substituents on the boron atom and thus making it possible to influence the catalytic activity of the complexes.
It is an object of the present invention to provide metallocene complexes which no longer have the disadvantages described, are simple to prepare and, in particular, offer the opportunity of influencing the electronic conditions on the cyclopentadienyl radicals.
We have found that this object is achieved by the metallocene complexes mentioned at the outset. Furthermore, we have found a process for preparing such metallocene complexes and the use of the metallocene complexes as catalyst components for the homopolymerization and copolymerization of C
2
-C
10
-&agr;-olefins.
As element of group III of the Periodic Table, particular mentioned may be made of boron and aluminum, with boron being particularly preferred.
Among the substituents which can act as the sole further substituent which occupies the third valence of the element of group III of the Periodic Table in addition to the bonds to a cyclopentadienyl radical and the other constituents of the bridge, particular mention may be made of organonitrogen, organophosphorus or organosulfur groups which, in addition to these heteroatoms, comprise up to 20 carbon atoms and up to 4 silicon atoms.
The metallocene complexes of the present invention may contain 1 or 2 cyclopentadienyl radicals. Preference is given to metallocene complexes of the formula I
where the variables have the following meanings:
M is a metal atom of transition group IV, V or VI of the Periodic Table,
D is an element of group III of the Periodic Table,
R
1
,R
2
,R
3
,R
4
are each hydrogen, C
1
- to C
10
-alkyl, 5-7-membered cycloalkyl which may in turn bear a C
1
-C
10
-alkyl group as substituent, C
6
- to C
15
-aryl or arylalkyl, where two adjacent radicals R
1
to R
4
may also form 5-7-membered cyclic groups which may in turn bear C
1
-C
10
-alkyl groups or SiR
6
3
groups as substituents or include further fused-on ring systems,
R
5
is hydrogen, C
1
-C
10
-alkyl, C
6
-C
15
-aryl or -arylalkyl or C
1
-C
10
-trialkylsilyl,
R
6
is C
1
-C
4
-alkyl,
m is the number of the transition group of the metal atom M minus 2,
n is 2 when X
1
is nitrogen or phosphorus and is 1 when X
1
is sulfur,
X
1
is nitrogen, phosphorus or sulfur,
X
2
is hydrogen, C
1
-C
10
-hydrocarbyl, N(C
1
-C
15
-hydrocarbyl)
2
or halogen,
A is a radical
 or a radical which is coordinated to M via an oxygen, sulfur, nitrogen or phosphorus atom.
Suitable metal atoms M are, in particular, the elements of transition group IV of the Periodic Table, i.e. titanium, zirconium and hafnium, with titanium and zirconium being preferred and zirconium being particularly preferred.
The cyclopentadienyl groups in formula I may be substituted or unsubstituted. Among the substituted metallocene complexes, those which are substituted by C
1
-C
4
-alkyl groups display particularly advantageous properties. Possible alkyl substituents are, for example, methyl, ethyl, n-propyl and n-butyl. The cyclopentadienyl radicals can be monosubstituted or polysubstituted, with monosubstituted and disubstituted cyclopentadienyl radicals having been found to be particularly advantageous. Preference is also given to cyclopentadienyl radicals in which 2 adjacent radicals R
1
to R
4
are joined to form 5- to 7-membered cyclic groups. Examples which may be mentioned are cyclopentadienyl groups derived from indenyl, tetrahydroindenyl, benzindenyl or fluorenyl, with these ring systems in turn being able to be substituted by C
1
-C
10
-alkyl groups or by trialkylsilyl groups.
In the metallocene complexes of the present invention having 2 cyclopentadienyl units, the bridging atom of the element of group III of the Periodic Table is directly bound to these two cyclopentadienyl units.
Among these dicyclopentadienyl complexes, particular preference is given to metallocene complexes in which
A is a radical
In the case of monocyclopentadienyl complexes, on the other hand, the radical A is not a cyclopentadienyl radical but rather a radical which is coordinated to M via an oxygen, sulfur, nitrogen or phosphorus atom. Possible groups A are, in particular, the following atoms or groups: —O—, —S—, —NR
9
—, —PR
9
— and uncharged 2-electron donor ligands such as —OR
9
, —SR
9
, —NR
9
2
or —PR
9
2
. In these formulae, R
9
is hydrogen or an alkyl, aryl, silyl, halogenated alkyl or halogenated aryl group having up to 10 carbon atoms. Particular preference is given to metallocene complexes in which A is a group
—ZR
7
2
—NR
8
—
in which
Z is silicon or carbon and
R
7
,R
8
are hydrogen, silyl, alkyl, aryl or combinations of these radicals having up to 10 carbon or silicon atoms.
Examples of radicals R
7
and R
8
are, in particular, hydrogen, trimethylsilyl, methyl, tert-butyl and ethyl. Z is preferably a

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