WO1998052953A1

WO1998052953A1 - Cyclooctatetraene compound

Info

Publication number: WO1998052953A1
Application number: PCT/NL1998/000283
Authority: WO
Inventors: Gerardus Johannes Maria Gruter; Uwe Helmut Heinz Steffan; Johannes Antonius Maria Van Beek
Original assignee: Dsm N.V.
Priority date: 1997-05-23
Filing date: 1998-05-18
Publication date: 1998-11-26
Also published as: NL1006123C2

Abstract

Metal complex containing a transition metal from groups 4-6 of the Periodic System of the Elements or a lanthanide and at least one cyclooctatetraene ligand, characterized in that the metal complex contains as a ligand at least one cyclooctatetraene compound according to the formula (I): (R'nDR)a-COT-(RUn)b where COT = a cyclooctatetraene, (C8R'8-a-b); R = a linking group between COT and the DR'n group or the Un group; D = an electron-donating heteroatom chosen from group 15 or group 16 of the Periodic System of the Elements; Un = an unsaturated hydrocarbon group; R' = a substituent; n = the number of times that R' occurs bonded to D; a = the number of R'nDR groups; and b = the number of Un groups, with 1≤a+b≤8.

Description

CYCLOOCTATETRAENE COMPOUND

The invention relates to a metal complex containing a transition metal from groups 4-6 of the Periodic System of the Elements or a lanthanide and at least one cyclooctatetraene ligand. Below, cyclooctatetraene will be abbreviated to COT.

Metal complexes that contain cyclopentadiene compounds (Cp compounds) as ligands are widely used as catalyst components in the polymerization of , in particular, defines. In many cases bridged Cp compounds are used as ligands (ANSA metallocenes) . Optionally, one of the Cp groups in such a ligand can be replaced by, for instance, an amide group or a phosphide group, as is for instance the case in the 'Constrained Geometry' catalyst components.

COT compounds are known, inter alia, from EP-A-0.672.676. Said publication also describes the use of these compounds as a ligand in metal complexes. ANSA metallocenes that contain a COT compound are not known. The invention is characterized in that the metal complex contains as a ligand at least one COT compound according to formula I

(R'_nDR)_a-COT- (RUn)_b (I)

where :

COT = a cyclooctatetraene, (C₈R'₈-a-b)

R = a linking group between COT and the DR'_n group or the Un group D = an electron-donating heteroatom chosen from group 15 or group 16 of the Periodic System of the Elements, Un = an unsaturated hydrocarbon group R' = a substituent n = the number of times that R' occurs bonded to D, a = the number of R'_nDR groups, and b = the number of Un groups , with 1 < a+b < 8.

It has now, surprisingly, been found that the metal complexes containing at least COT compound according to the invention are very useful catalyst components for olefin polymerizations. In the metal complex according to the invention the COT-containing ligand has a strongly stabilizing effect.

One skilled in the art cannot deduce from EP-A-0.672.676 that the compounds according to the invention could have such a specific action.

The COT compound consists of a cyclooctatetraene with at least 1 and at most 8 substituents of the form -RDR'_n and/or -RUn. The cyclooctatetraene can also be substituted with substituents R' other than the above-mentioned substituents. These substituents R' attached to COT may be the same or different and are, for instance, hydrogen or hydrocarbon substituents with 1-20 carbon atoms or substituted hydrocarbon substituents in which one or more hydrogen atoms have been substituted by halogen atoms, halogen substituents or organic silyl substituents. The substituents may also contain other elements from groups 14-17 of the Periodic System of the Elements. Examples of hydrocarbon substituents are alkyl, aryl and aralkyl substituents, such as for instance methyl, ethyl, propyl, isopropyl, butyl, hexyl, octyl, 2-ethylhexyl, decyl, phenyl, benzyl, dimethyl aminoethyl or methoxyethyl . It is also possible for two adjacent hydrocarbon substituents to be connected to form a ring system, such as for instance benzoylcyclooctatetraene . Examples of halogen substituents are fluorine, chlorine and bromine. Examples of organic silyl substituents are trimethylsilyl, triethylsilyl, phenyldimethylsilyl, diphenylmethylsilyl, triphenylsilyl and (dimethyl) - (dimethylamino) silyl .

R is a group connecting COT with the DR'_n group or the Un group. R can be a hydrocarbon group with 1-20 carbon atoms. Examples of these groups are methylene, ethylene, propylene, butylene, phenylene, substituted or not with one or more side chains . Preferably, R has the following structure:

(-ER"₂-)

where p = 1-4 and E an atom from group 14 of the Periodic System of the Elements . The R" groups may each separately be hydrogen or a hydrocarbon radical, which can be chosen from the above-mentioned group of substituents R' . Besides carbon, the main chain of R may also contain Si or Ge. Examples of these R groups are: dialkylsilylene, dialkylgermylene, tetraalkyldisilylene, dialkylsilaethylene (-SiR"₂CH₂-) or tetraalkyl-silaethylene (-SiR"₂CR"₂-) . The R" groups in such R groups are preferably hydrogen or an alkyl group containing 1-4 carbon atoms and are further preferred to be methyl or ethyl . The DR'_n group consists of a heteroatom D chosen from group 15 or group 16 of the Periodic System of the Elements and one or more substituents R' bound to D. Here and hereinafter Periodic System of the Elements is understood to be the Periodic System that is represented on the inside of the cover of the Handbook of Chemistry and Physics, 70th Edition, 1980/1990 (New IUPAC Notation) .

The heteroatom D is preferably nitrogen (N) , oxygen (O) , phosphorus (P) or sulphur (S) . The Un group is an unsaturated hydrocarbon group, which may either be substituted or unsubstituted. The Un group may be an anionic group or a neutral group. Examples of Un groups are cyclooctatetraene (COT) , cyclopentadiene (Cp) , tetramethylcyclopentadiene, indenyl, fluorenyl, phenyl, tolyl, xylyl, mesitylyl, cumyl, tetramethylphenyl and pentamethylphenyl .

The substituents R' attached to D can be chosen from the above-mentioned group of substituents R Preferably, R' attached to D is alkyl. Two R' groups may further be connected to form a ring structure (so that, for instance, the DR'_n group is a pyrrolidinyl group) .

In the metal complexes according to the invention the metal is preferably Ti, Hf , Zr or V.

The size of R in the COT compound is critical in the sense that the size of R determines the accessibility of the metal by the DR'_n group or the Un group in the metal complex according to the invention, so that the desired intramolecular co-ordination is possible or intramolecular covalent bonding can occur. If R is too short, co-ordination or bonding cannot occur due to ring strain.

The number of substituents R' that is present in the DR'_n substituent in the COT compound according to the invention depends on the nature of the heteroatom D, but also on co-ordination or covalent bonding of the COT compound with the metal in the metal complex in the sense that n=l if D originates from group 15 and there is covalent bonding with the metal (tri-anionic bidentate ligand) ; n=2 if D originates from group 15 and co-ordination with the metal occurs (di-anionic bidentate ligand; n=0 if D originates from group 16 and there is covalent bonding with the metal (tri-anionic bidentate ligand) and n=l if D originates from group 16 and coordination with the metal occurs (di-anionic bidentate ligand) . If the Un group in the metal complex is di-anionic, for instance COT or substituted COT, then there is a tetra-anionic bidentate ligand. If the Un group in the metal complex is mono-anionic, for instance cyclopentandienyl, then there is a tri-anionic bidentate ligand, and if the Un group in the metal complex is neutral, for instance an aryl group, there is a di-anionic bidentate ligand. In this case there is intramolecular coordination of the aryl group to the transition metal.

The metal complexes according to the invention that contain a COT compound are highly suitable as catalyst components for the polymerization of olefines. The term olefines here and hereinafter denotes α-olefines, di-olefines and other ethylenically unsaturated monomers. Polymerization of olefines is understood to mean both the polymerization of a single type of olefinic monomer and the copolymerization of two or more olefines.

These polymerizations can be carried out in the way known per se for this and the use of the transition metal complexes as catalyst components in combination with the ion complex does not necessitate any essential change of these processes. The known polymerizations are carried out in suspension, emulsion, gas phase or as bulk polymerization. The polymerizations are carried out at temperatures of between -50 °C and +350 °C. The polymerization of α- defines is preferably carried out at a temperature higher than 100 °C. The pressures used are generally between atmospheric pressure and 250 MPa; for bulk polymerizations more in particular between 50 and 250 MPa, for the other polymerization processes between 0.5 and 25 MPa. As dispersants and solvents use can be made, for instance, of hydrocarbons such as pentane, heptane and mixtures thereof. Aromatic, optionally perfluorinated hydrocarbons are also suitable. It is also possible to use the monomer to be used in the polymerization as dispersant or solvent.

The COT compounds according to the invention can for instance be synthesized in the following manner. The synthesis of mono-substituted COT compounds is started from bromocyclooctatetraene (3) , which can be prepared from COT on a large scale at a low temperature. Dimethyl chlorosilyl cyclooctatetraene (5) can be prepared from cyclooctatetraenyl lithium (4) . Starting from compound (5) it is, for instance, possible to synthesize COT compounds with R'_nNSi(CH₂)2 substituents in a simple way through reaction with an excess of primary or secondary amines. Starting from compound (5) is it also possible to synthesize COT compounds with, for instance, cyclopentadienyl dimethylsilyl ligands. This compound can, for instance, be synthesized by allowing compound (5) to react with NaCp.

Me = methyl

Bu = butyl

<< = excess.

The processes for the preparation of the transition metal complex according to the invention from the COT compounds are known to one skilled in the art and can be carried out by him in the customary manner.

The invention will be elucidated on the basis of the following examples, without however being restricted thereto. Examples Experimental

The COT compounds were characterized by means of GC-MS (type Fisons MD800, equipped with a quadrupde mass detector, Fisons AS800 autoinjector and CPSillδ column (30 m x 0.25 mm x 1 μm, low bleed) with one of the following temperature programmes: 50 °C (5 min.), rate: 7.5 °C/min., 250 °C (29 min.) or 150 °C (5 min.), rate: 7.5 °C/min. , 250 °C (29 min.)) and NMR Bruker ACP 200 (^=400 MHz; ¹³C=100 MHz) . Metal complexes were characterized using a Kratos MS 80 or Finnigan Mat 4610 mass spectrometer. All reactions were carried out under a nitrogen atmosphere.

Example I

Preparation of bromocyclooctatetraene (COTBr)

16 ml (0.14 mol) of COT was dissolved in 100 ml of dichloromethane and cooled to -60 °C. 7.7 ml of bromine (0.15 mol) in 40 ml of dichloromethane was added dropwise with stirring in two hours . This reaction mixture was then kept at -60 °C and stirred for another 45 minutes. Then 25.1 g of potassium-t-butoxide (0.22 mol) was added in a 4-hour period while the temperature stayed at -60 °C. During this step the solution gradually changed from a bright yellow solution into a mustard-coloured, turbid mixture.

The reaction mixture was stirred overnight (about 13 hours) at a temperature of -45 °C. Then the reaction mixture was slowly heated to -10°C in a period of 3 hours, during which time the mixture gradually became darker brown.

The mixture was then added to 200 ml of ice-cooled distilled water in which 3.5 ml of acetic acid had been dissolved. It was subsequently filtered and 150 ml of dichloroethane was used to wash the flask and the residue. The product was extracted with dichloromethane . The organic phases were combined and washed with 200 ml of concentrated sodium bicarbonate solution and five times with 100 ml of distilled water. They were then dried over magnesium sulphate and filtered. The solvent was evaporated and the crude product was distilled at 40 °C at a pressure of 5 x 10^"3 mbar. Yield: 19.25 g; purity 95%.

Example II Preparation of chlorodimethylsilyl cyclooctatetraene

56 ml of 1.56M butyl lithium (0.09 mol) was cooled to -60 °C. In one hour and with stirring 16.2 g of COTBr (0.09 mol) in 40 ml of ether was added dropwise. During the dropwise addition the temperature was maintained at -60 °C, after which the mixture was gradually heated to -30 °C (in about another hour) .

Then the mixture was kept at a temperature of -35 to -30 °C and subsequently it was added in 45 minutes and with stirring to a solution of 43 ml of SiMe₂Cl₂ (0.35 mol) in 100 ml of diethylether at room temperature. Stirring of the reaction mixture was continued overnight at room temperature.

The mixture was filtered and the solvent was evaporated. The crude product was condensed (45 °C, 1 x 10^"3 mbar) . The yield was 12.1 g. The purity achieved was 88% (GC) .

The product was characterized by means of NMR and GCMS. Example III

Preparation of (N.N-dimethylamino) dimethylsilyl cyclooctatetraene 5.65 g (purity 88%, 0.025 mol) of COTSiMe₂Cl was dissolved in 150 ml of tetrahydrofuran (THF) and added dropwise, in 30 minutes and with stirring, to a solution of 160 ml of 2M dimethylamine (0.32 mol) in THF. The reaction was carried out at room temperature and stirring of the mixture was continued over the weekend. The solvent and the amine excess were then evaporated (using a water bath at 40 °C) , which yielded an oil-like orange residue. This was extracted with 70 ml of special boiling point gasoline (SBPG) and filtered. The solvent was re-evaporated, yielding an orange residue. This was distilled (80 °C, 0.1 mbar) and yielded 3.37 g of a yellow oil; purity 88% (GC) .

The product was characterized by means of NMR and GCMS.

Example IV

Preparation of dimethyl (N-methylamino) silyl cyclooctatetraene

1.44 g of COTSiMe₂Cl, dissolved in 25 ml of THF and 22 ml of a 2M methylamine solution in THF were introduced into a flask, under nitrogen, and cooled to -70 °C by means of a bath of dry ice and acetone. The COTSiMe₂Cl solution was first slowly and then fully added with stirring at a temperature of -70 °C. The mixture was then allowed to heat up slowly.

When a temperature of -50 °C was reached, some precipitate was observed. After three hours the temperature was 12 °C and the solution had a milky yellow colour, while the amount of precipitate had increased substantially. After three and a half hours the solution was at room temperature (20 °C) and the solvent and the amine excess were evaporated and the crude product was condensed using a warm-water bath (40 °c) .

20 ml of SBPG was added and decanted, after which another 10 ml of SBPG was added, which was also decanted. The solvent was then evaporated and the crude product was condensed. The yield was 0.46 g. The product was characterized by means of

NMR and GCMS.

Example V

Preparation of N-t-butylaminodimethylsilyl cyclooctatetraene

A solution of 1.04 g of COTSiMeCl (5.3 x

10^"3 mol) in 34 ml of THF was added in 20 minutes with stirring to a solution of 6 ml of t-butylamine (0.06 mol) at room temperature. The solution, with a milky white colour, was stirred further at room temperature and turned yellow within 30 minutes. Stirring of the reaction mixture was continued over the weekend. The solvent and the amine excess were evaporated, yielding a yellow, oil-like residue. This was extracted with 20 ml of SBPG and decanted. The solution was filtered and then the SBPG was evaporated, yielding a yellow residue.

The yield was about 100%.

The product was characterized by means of NMR and GCMS. Example VI

Preparation of cvclopentadienyldimethylsilyl cyclooctatetraene

1.5 ml of a 30 wt.% suspension of sodium in toluene (0.017 mol) was diluted with 10 ml of THF. With stirring 0.66 g of cyclopentadiene (1 x 10^"2 mol) was added at room temperature. This mixture was stirred further overnight .

2.56 g of COTSiMe₂Cl was dissolved in 15 ml of THF and added dropwise in 30 minutes at room temperature to the sodium-Cp salt. This reaction mixture was then stirred for another hour.

Since the salt to be prepared (NaCl) is soluble in THF, the solvent was evaporated and replaced by 50 ml of SBPG. The solution was subsequently filtered and the solvent re-evaporated. The crude product was condensed (60 °C, 6 x 10^"3 mbar) and yielded 1.56 g.

The product was characterized by means of NMR and GCMS.

Example VII

Preparation of KAC0TSiMeCp1

A lump of potassium (1 g) was introduced into 15 ml of THF, followed by stirring. At room temperature COTSiMe₂Cp (purity 94%, 4.9 mmol) was added with stirring. Initially, strong gas formation took place, but this soon stopped. The solution slowly turned yellow and after some time it turned dark green within a few seconds. Within 18 hours the solution became dark red and some precipitate formed, which was removed by filtration and vacuum-dried. The solvent was removed in a vacuum and the residue was dried. Example VIII

Preparation of K₂rC0TSiMe₂NMe₂l

A lump of potassium (1 g) was introduced into 20 ml of THF. COTSiMe₂NMe₂ (1.5 g, 6.3 mmol) was added to this mixture. The mixture was stirred for 78 hours upon which its colour changed to dark yellow- brown. The solution was decanted off from the potassium and used without further purification.

Example IX

Preparation of ZrCOTSi (MeNMe ) Cl₂

1.5 g of zirconium tetrachloride (6.3 mmol) was suspended in 15 ml of SBPG. THF (30 ml) was added dropwise with stirring. A solution of K₂COTSiMe₂NMe₂ (1.8 g, 6.3 mmol) in 20 ml of THF was added and the mixture was refluxed for 8 days. Then the solvent was withdrawn in a vacuum and the residue was extracted with warm toluene in an extractor. Upon completion of the extraction the volume of the solution was reduced until crystals were deposited. The solution was then heated to 80 °C until the crystals had dissolved again. Subsequently, the solution was slowly cooled to room temperature. The orange crystals were removed by filtration, washed twice with 10 ml of SBPG and vacuum- dried.

The product was characterized by means of NMR and elemental analysis .

Exam l X Preparation of ZrCOT (COTSi (MeNME)

ZrCOTCOTSiMeNME₂Cl2 (170 mg, 0.46 mmol) was dissolved in 20 ml of toluene and cooled to -50 °C. At that temperature a solution of K₂COT (0.46 mmol) in 5 ml of THF was added with stirring. The mixture immediately got a dark colour. Then it was allowed to warm up to room temperature, upon which the solution assumed a dark red colour. The solvent was removed in a vacuum and the red powder that remained was extracted twice with 10 ml of toluene. The solution was filtered and its volume reduced to 5 ml. Then SBPG (8 ml) was added, the mixture was heated to 50°C and slowly cooled to -80 °C. The crystals were removed by filtration and vacuum- dried. Yield: 90 mg.

The product was characterized by means of NMR.

Example XI

Preparation of 1.4-bis (chlorodimethylsilyl) cycloocta- 2,5,7-trjene

A solution of K₂C0T (89 mmol) in 150 ml of THF was added dropwise, with stirring, to a solution of SiMe₂Cl₂ (46 g, 360 mmol, 43 ml) in 100 ml of THF. The K₂C0T solution immediately changed colour and the temperature of the mixture rose slightly. The mixture was stirred overnight, the solvent was removed in a vacuum and the residue was extracted with 400 ml of SBPG. The suspension was filtered and the residue was washed with 200 ml of SBPG. The solvent was removed and dried in a vacuum.

The oil-like product could be recrystallized at -80 °C from 100 ml SBPG, which yielded white crystals; the larger part of the product, however, remained in solution. Yield: 9 g (35%) .

The product was characterized using NMR. Example XII

Preparation of 1.4-bis (N.N- dimethylaminomethylsilyl) cycloocta-2 , 5.7-triene (COT^A

A solution of 1,4-bis (chlorodimethylsilyl) - cycloocta-2,5,7-triene (4.1 g, 14 mmol) in 60 ml of THF was added at 0 °C with stirring to 60 ml of a 2M solution of dimethylamine in THF. The mixture was then stirred for 2 hours at room temperature and the solvent was removed in a vacuum. The residue was extracted with 70 ml of SBPG and filtered; the solvent was removed in a vacuum, which yielded a yellowish oil.

Yield: 4.1 g

The product was characterized by means of

NMR.

Example xiu

Preparation of dipotassium-1.4-bis (N.N- dimethylaminodimethvlsilyl cyclooctatetraenediide (K₂C0T^{^}) 1,4 bis(N,N- dimethylaminodimethylsilyl) cycloocta-2, 5, 7-triene (4.1 g, 13.3 mmol) was dissolved in 60 ml of THF and potassium (1.5 g) was added. The mixture was stirred for 18 hours and gradually turned dark red. The solution was used without further purification.

Example XIV Preparation of ZrCOT₂ ^AA

A solution of K₂COT^AA (6.7 mmol) in 30 ml of THF was added dropwise to a suspension of ZrCl₄ (0.77 g, 3.3 mmol) in 20 ml of toluene. The red colour changed and the temperature of the mixture rose slightly. After 18 hours' stirring at 50 °C the solvent was removed in a vacuum, the residue was extracted with 30 ml of SBPG and the mixture was filtered. The solvent was again removed in a vacuum and the residue was dried.

Example XV

Polymerisation of ethylene

To a 1.3 litre reactor was added 400 mL of pentamethylheptane (PMH) , and ethene was dosed, while the reactor was heated to polymerisation temperature (150°C) ; the pressure was 2 MPa. Subsequently, 0.2 mmol of trioctyl aluminium (TOA) was added. Then 10 μmol of the catalyst according to example X was premixed with 20 μmol of [PhNMe₂H] B (C₆F₅) ₄] as cocatalyst at room temperature during 1 minute in 10 mL PMH, after which it was dosed to the reactor. The dosing vessel was flushed with 100 mL of PMH. The pressure in the reactor was kept constant by dosing of ethylene. By cooling, the reactor temperature was kept within 5°C band of the set temperature of 150°C. After 10 minutes, the polymerisation was stopped, and the polymer was obtained by evaporation of the crude solution at 50°C. 7.3 g polyethylene was obtained. The yield was 4 kg/g Zr*5 min.

Claims

C I S

1. Metal complex containing a transition metal from groups 4-6 of the Periodic System of the Elements or a lanthanide and at least one cyclooctatetraene ligand, characterized in that the metal complex contains as a ligand at least one cyclooctatetraene compound according to formula I

(R'_nDR)_a-COT-(RUn)_b (I)

where : C0T= a cyclooctatetraene, (C₈R'8-a-b)

R = a linking group between COT and the DR'_n group or the Un group, D = an electron-donating heteroatom chosen from group 15 or group 16 of the Periodic System of the Elements,

Un = an unsaturated hydrocarbon group, R' = a substituent, n = the number of times that R' occurs bonded to D, a = the number of R'_nDR groups, and b = the number of Un groups, with 1 < a+b < 8.

2. Metal complex according to claim 1, characterized in that the cyclooctatetraene compound contains at least an -RDR'_n group.

3. Metal complex according to claim 2, characterized in that D = N, P, 0 or S.

4. Metal complex according to any one of claims 1-3, in which the metal is present in another valency than the highest one. Metal complex according to any one of claims 1-4, in which the transition metal has been chosen from the group consisting of Ti, Hf, Zr and V. Use of a metal complex according to any one of claims 1-5 as a catalyst component. Use of a metal complex according to any one of claims 1-5 as a catalyst component in the polymerization of ╬▒-olefines.