The invention relates to a substituted cyclopentadiene compound.

Cyclopentadiene compounds, both substituted and unsubstituted, are used widely as a starting material for preparing ligands in metal complexes having catalytic activity. In by far the majority of the cases either unsubstituted cyclopentadiene or cyclopentadiene substituted with one to five methyl groups is used. As metals in these complexes use is made in particular of transition metals and lanthanides.

Also known are cyclopentadiene compounds with a substituent of the form -(ER ₂ ) _p D(R ' ) _n H, where E is an atom chosen from group 14 of the Periodic System of the

Elements, D is a hetero atom chosen from group 15 or 16 of the Periodic System of the Elements, R and R' are substituents, n is the number of R' groups bonded to D and p = 1-4. These compounds are described for instance in EP-A-0.420.236 and WO-A-93/08221. These compounds are very suitable as ligands in olefin polymerization catalysts.

In the following, cyclopentadiene will be abbreviated as Cp. The same abbreviation will be used for a cyclopentadienyl group if it is clear, from the context, whether cyclopentadiene itself or its anion is meant .

For the Periodic System of the Elements, see the new IUPAC notation to be found on the inside of the cover of the Handbook of Chemistry and Physics, 70th edition, 1989/1990.

A drawback of the known substituted Cp compounds is that when used as a ligand in a metal complex they do provide it with a certain degree of stability, but at elevated temperatures the stability of these complexes declines faster than desirable. The object of the invention is to provide substituted Cp compounds which comprise a substituent of the form -(ER ₂ ) _p D(R ' ) _n H, where E is an atom chosen from group 14 of the Periodic System of the Elements, D is a hetero atom chosen from group 15 or 16 of the Periodic System of the Elements, R and R' are substituents, n is the number of R' groups bonded to D and p = 1-4 and which, when used as a ligand in a metal complex, provide it with a better stability than the known Cp compounds.

This object is achieved according to the invention in that at least one other substituent is a branched alkyl group with at least 3 carbon atoms, 1 t- butyl group being excluded as sole other substituent. The presence of at least one branched alkyl group instead of hydrogen or methyl groups in a metal complex appears to result in a better resistance against elevated temperatures than if other Cp compounds are used as ligands. Highly suitable branched alkyl groups are secondary alkyl groups, tertiary alkyl groups and cyclic alkyl groups. By preference, 1 to 4 branched alkyl groups are substituted on the Cp compound according to the invention. The branched alkyl groups can be either identical or different. Particularly suitable branched alkyl groups are, for example, 2-pentyl, 2-hexyl, 2- heptyl, 3-pentyl , 3-hexyl, 3-heptyl, 2-(3-methylbutyl ) , 2-(3-methylpentyl) , 2-(4-methylpentyl) , 3-(2- methylpentyl) , 2-(3 ,3-dimethylbutyl) , 2-(3- ethylpentyl) , 2-(3-methylhexyl) , 2-(4-methylhexyl) , 2- (5-methylhexyl) , 2-(3 , 3-dimethylpentyl ) , 2-(4, 4-

dimethylpentyl) , 3-(4-methylhexyl) , 3-(5-methylhexyl) , 3-(2 , 4-dimethylpentyl) , 3-(2-methylhexyl ) , 3-(4,4- dimethylpentyl) , l-(2-ethylbutyl ) , l-(2-methyl-3- chloropropyl ) , 2-(1-chloropropyl ) , l-(3-methylbutyl ) , 4-(2-methylbutenyl ) , l-(2-methylpropyl ) , l-(2- ethylbutyl), 1-(3-chloro-2-methylpropyl ) , 2-(l- chloropropyl) , l-(2-methylbutenyl ) and l-(2- methylpropyl ) .

Optionally, several branched alkyl groups are present as substituents; these can be identical or different. Besides the branched alkyl group which is a reguired substituent in the compound according to the invention and the substituent having the form - (ER ₂ ) _p D(R ' ) _n H, other substituent groups can be present on the remaining positions of the Cp. These can be chosen for instance from alkyl groups, linear as well as cyclic ones, aryl and aralkyl groups. Apart from carbon and hydrogen, one or more hetero atoms from groups 14-17 of the Periodic System of the Elements can also be present, for example 0, N, Si or F.

Examples of suitable further groups are methyl, ethyl, n-butyl , n-pentyl , n-hexyl and n-octyl, benzyl, phenyl and tolyl.

Metal complexes which are catalytically active if one of their ligands is a compound according to the invention are complexes of metals from groups 4- 10 of the Periodic System of the Elements and rare earths. In this context, complexes of metals from groups 4 and 5 are preferably used as a catalyst component for polymerizing olefins, complexes of metals from groups 6 and 7 in addition also for metathesis and ring-opening metathesis polymerizations, and complexes of metals from groups 8-10 for olefin copolymerizations with polar comonomers, hydrogenations and carbonylations.

Particularly suitable for the polymerization of olefins are such metal complexes in which the metal

is chosen from the group consisting of Ti, Zr, Hf , V and Cr .

Substituted Cp compounds can, for instance, be prepared by reacting a halide of the substituting compound in a mixture of the Cp compound and an aqueous solution of a base in the presence of a phase transfer catalyst. By Cp compounds are understood here Cp as such and Cp which is already substituted in at least one position, with the possibility of two substituents forming a closed ring. The process described in the following thus enables unsubstituted compounds to be converted to mono- or polysubstituted ones, but also already mono- or polysubstituted Cp-based compounds to be substituted further, which can be followed by ring closure.

The reaction can be carried out with a virtually equivalent quantity with respect to the Cp compound of the halogenated substituting compound. An equivalent quantity is understood as a quantity in moles which corresponds to the desired substitution multiplicity, for example 2 mol per mole of Cp compound if disubstitution with the substituent in question is intended.

Depending on the size and the associated steric hindrance of the substituting compounds it is possible to obtain trisubstituted to pentasubstituted Cp compounds. If a reaction with a tertiary halide of a substituting compound is carried out, as a rule only trisubstituted Cp compounds can be obtained, whereas with a primary and secondary halide of a substituting compound it is generally possible to achieve tetra and often even pentasubstitution.

The substituents are preferably used in the method in the form of their halides and more preferably in the form of their bromides. If bromides are used a smaller quantity of phase transfer catalyst is found to be sufficient, and a higher yield of the compound aimed

for is found to be achieved.

By means of this method it is also possible, without intermediate isolation or purification, to obtain Cp compounds which are substituted with specific combinations of substituents. Thus, for example, disubstitution with the aid of a certain halide of a substituting compound can first be carried out and in the same reaction mixture a third substitution with a different substituent can be carried out, by adding a second, different halide of a substituting compound to the mixture after a certain time. This can be repeated, so that it is also possible to prepare Cp derivatives having three or more different substituents.

The substitution takes place in a mixture of the Cp compound and an aqueous solution of a base. The concentration of the base in the solution is in the range between 20 and 80 wt.%. Hydroxides of an alkali metal, for example K or Na are highly suitable as a base. The base is present in an amount of 5-30 mol per mole of Cp compound, preferably 7-15 mol per mol. The substitution takes place at atmospheric or elevated pressure, for instance up to 100 MPa, which higher level is applied in particular if volatile components are present. The temperature at which the reaction takes place may vary within wide limits, for instance from -20 to 120°C, preferably between 10 and 50°C. Starting up the reaction at room temperature is usually suitable after which the temperature of the reaction mixture can rise due to the heat released in the reactions or as a result of external heating.

The substitution takes place in the presence of a phase transfer catalyst which is able to transfer OH-ions from the aqueous phase to the organic phase containing Cp compound and halide, the OH-ions reacting in the organic phase with a H-atom which can be split off from the Cp compound. The phase transfer catalysts are used in an amount of 0.01 - 2 equivalents on the

basis of the amount of Cp.

The various components can be supplied to the reactor in various sequences in the implementation of the process. Upon completion of the reaction the aqueous phase and the organic phase containing the Cp compound are separated. When necessary the Cp compound is recovered from the organic phase by fractionated distillation. Depending on the size and the associated steric hindrance of the compounds to be substituted it is possible to obtain trisubstituted to hexasubstituted Cp compounds.

The substituted Cp compound according to the invention further comprises at least one substituent of the form -(ER ₂ ) _p D(R ' ) _n H, where p = 1-4. E is chosen from group 14 of the Periodic System of the Elements and so can be C, Si, Ge and Sn. By preference, E is Si or Ge. D is chosen from group 15 or 16 of the Periodic System of the Elements. If D is chosen from group 15, the coordination number of the element is 3, while if D is chosen from group 16, the coordination number of the element is 2. By preference, D is N, 0, P or S. By special preference, D is a nitrogen atom. R and R' are substituents and can each separately be a hydrocarbon radical with 1-20 carbon atoms (such as alkyl, aryl, aralkyl, etc.). Examples of such hydrocarbon radicals are methyl, ethyl, propyl, butyl, hexyl, decyl, phenyl, benzyl and p-tolyl. R' can also be a substituent which, in addition to or instead of carbon and/or hydrogen, comprises one or more hetero atoms from groups 14-16 of the Periodic System of the Elements. Thus a substituent can be a group comprising N, 0 and/or Si. The letter n represents the number of substituents bonded to D and is 1 if D is chosen from the group 15 elements and is 0 if D is chosen from the group 16 elements.

A Cp compound comprising a substituent of the form -(ER ₂ ) _p D(R ' ) _n H can be synthesized starting from a Cp compound substituted with at least one branched alkyl group having at least three carbon atoms. This substituted Cp compound is deprotonated to the anion by means of a base, sodium or potassium.

As base can be applied for instance organolithium compounds (R ³ Li) or organomagnesium compounds (R ³ MgX), where R ³ is an alkyl, aryl, or aralkyl group and X is a halide, such as for instance n-butyl lithium or i-propylmagnesium chloride. Potassium hydride, sodium hydride, inorganic bases, such as NaOH and KOH, and alcoholates of Li, K and Na can also be used as base. Mixtures of the above- mentioned compounds can also be used.

Next the anion obtained is reacted with a compound of the formula (R ₂ E) _p X ₂ and the resulting reaction product is reacted with a compound of the form LiD(R') _n H or with a compound of the form DR' _n H ₂ , where X, D, R, R', n and p are as defined in the foregoing. This process is described more specifically in EP-A- 0.420.236.

Metal complexes comprising at least one cyclopentadiene compound as defined in the foregoing, appear to possess improved stability in comparison with complexes comprising Cp compounds as ligands as described in EP-A-0.420.236. The invention therefore also relates to said metal complexes and their use as a catalyst component in the polymerization of olefins. The synthesis of metal complexes with the above-described specific Cp compounds as a ligand can take place according to the methods known per se for this purpose. The use of these Cp compounds does not require any adaptations of said known methods. The polymerization of α-olefins, for example ethene, propene, butene, hexene, octene and mixtures thereof and combinations with dienes, can be carried

out in the presence of the metal complexes with the cyclopentadienyl compounds according to the invention as a ligand. Suitable in particular for this purpose are complexes of transition metals in which just one of the cyclopentadienyl compounds according to the invention is present as a ligand. Said polymerizations can be carried out in the manner known for the purpose and the use of the metal complexes as catalyst component does not make any essential adaptation of these processes necessary. The known polymerizations are carried out in suspension, solution, emulsion, gas phase or as bulk polymerization. The cocatalyst usually applied is an organometal compound, the metal being chosen from Groups 1, 2, 12 or 13 of the Periodic System of the Elements. To be mentioned are for instance alkylaluminooxanes (such as methylaluminoxanes) , tris(pentafluorophenyl) borate, dimethylanilinium tetra(pentafluorophenyl) borate or mixtures thereof. The polymerizations are carried out at temperatures between -50°C and +350°C, more particularly between 25 and 250°C. The pressures used are generally between atmospheric pressure and 250 MPa, for bulk polymerizations more particularly between 50 and 250 MPa, and for the other polymerization processes between 0.5 and 25 MPa. As dispersants and solvents, use may be made of, for example, hydrocarbons, such as pentane, heptane and mixtures thereof. Aromatic, optionally perfluorinated hydrocarbons, are also suitable. The monomer applied in the polymerization can also be used as dispersant or solvent.

The invention will be elucidated by means of the following examples, without being restricted thereto. For characterization of the products obtained the following analysis methods are used.

Experimental

Dimethoxymethane was distilled from potassium-sodium alloy, benzophenone being used as indicator. The reactions were monitored by means of gas chromatography (GC type: Hewlett Packard 5890 Series II, equipped with autosampler type HP6890 Series Injector, integrator type HP3396A and HP Crosslinked Methyl Silicon Gum (25 m x 0.32 mm x 1.05 μm ) column with one of the following temperature programmes: 50°C (5 min.) rate: 7.5°C/min. 250°C (29 minutes) or 150°C (5 min.) rate: 7.5°C/min. 250°C (29 minutes). The products were characterized using GC-MS (type Fisons MD800, equipped with a quadrupole mass detector, autoinjector Fisons AS800 and CPSilδ column (30 m x 0.25 mm x lμm, low bleed) with one of the following temperature programmes: 50°C (5 min.) rate: 7.5°C/min. 250°C (29 minutes) or 150°C (5 min.) rate: 7.5°C/min. 250°C (29 minutes) and NMR Bruker ACP200 ( ^X H - 200 MHz.; ¹³ C = 50 MHz) or Bruker ARX400( ¹ H = 400 MHz.; ¹³ C = 100 MHz). Complexes were characterized using mass spectrometer Kratos MS80 or Finnigan Mat 4610.

Example I: the preparation of van (N-t- butylamino) (dimethyl ) (2 ,3,5-tri-2- butylcvclopentadienyl)silane titanium dichloride

Example Ia: Preparation of tri (2-butyl )cyclopentadiene A double-walled reactor having a capacity of 1 1 and provided with baffles, cooler, top stirrer, thermometer and dropping funnel was filled with 400 g (5.0 mol) of clear 50% NaOH . Then 9.6 g (24 mmol) of Aliquat 336 and 15.2 g (0.23 mol) of freshly cracked cyclopentadiene were added. The reaction mixture was vigorously stirred for several minutes. Then 99.8 g (0.73 mol) of 2-butyl bromide were added in half an hour. During this process, the mixture was cooled with water. After stirring for half an hour at room

temperature, the reaction mixture was heated to 70°C, after which stirring was carried out again for three hours. Stirring was stopped and phase separation was awaited. The water layer was drained off and 400 g (5.0 mol) of fresh 50% NaOH were added. Then stirring was carried out for a further 2 hours at 70°C. It was demonstrated with GC that more than 90% tri(2- butyl )cyclopentadiene was present in the mixture of di- , tri- and tetra(2-butyl)cyclopentadiene at that instant. The product was distilled at 1 mbar and 91°C. After distillation, 40.9 g of tri(2- butyl)cyclopentadiene were obtained. The characteriz¬ ation was carried out with the aid of GC, GC-MS, ¹³ C- and -H-NMR.

Example IB: the preparation of (N-t- butylamino) (dimethyl ) (2 , 3 , 5-tri-2- butylcyclopentadienyl )silane

In a 2-litre glass flask 23.4 g of tri(2- butyl)cyclopentadiene (0.1 mol) was dissolved in 1 litre of dry THF with thorough stirring. This solution was cooled to 0°C by means of an ice bath. 62.5 ml of a 1.6M solution of butyl lithium in hexane (0.1 mol) was slowly added to the cooled solution. A light-yellow solution was obtained, which was stirred at room temperature for two hours. In approximately 4 hours' time this solution was added to a solution of 42.4 ml of dimethyldichlorosilane (0.35 mol) in 300 ml of dry THF in a 2-litre flask. A light-yellow solution formed, which was stirred for about three more hours at room temperature. Then the solvent and the excess of dimethyldichlorosilane were evaporated at 50°C and a 10 mm mercury pressure. The residue, a bright yellow liquid with some solid substance (LiCl), was added in about 1 hour's time to a solution of 54 ml of tertiary butylamine (0.5 mol) in 300 ml of dry THF in a 1-litre glass flask which was cooled by means of an ice bath.

Then the ice bath was removed and the reaction mixture obtained was stirred for about 10 hours. The precipitate formed was filtered off through a Bϋchner funnel. The yellow filtrate was boiled down at 50°C and a 10 mm mercury pressure. Vacuum distillation of the residue ultimately yielded 20 g of pure (N-t- butylamino) (dimethyl ) (2 , 3,5-tri-2- butylcyclopentadienyl )silane.

Example IC: the preparation of van (N-t- butylamino) (dimethyl ) (2 , 3 , 5-tri-2- butylcyclopentadienyl )silane titanium dichloride

Under an inert atmosphere (dried nitrogen) in a 200-ml Schlenk flask, 3.64 g of (N-t- butylamino) (dimethyl) (2 , 3, 5-tri-2- butylcyclopentadienyl)silane (10 mmol) was dissolved in 75 ml of diethyl ether. With stirring, this solution was cooled to 0°C with the aid of an ice bath. In approximately 5 minutes' time 12.5 ml of a 1.6M butyl lithium solution in hexane was added to this. Then the ice bath was removed and the solution was stirred for two hours at room temperature. A bright yellow solution was obtained. This reaction mixture was cooled to -78°C (dry-ice bath; at this low temperature a small amount of white precipitate formed) and through a bend or connector it was added to a blue slurry of 3.71 g of titanium trichloride (complexed with 3 equivalents of THF: "TiCl ₃ .3THF"; 10 mmol) which also had been cooled to -78°C. The reaction mixture assumed a dark colour, which became even much darker (purple/brown/black) when the dry-ice bath had been removed and the reaction mixture had been allowed to warm up to room temperature. After some 14 hours' stirring, 1.45 g of silver chloride (AgCl) was added (10.1 mmol). The reaction mixture was stirred for 15 hours at room temperature, during which time the colour of the mixture turned to red, while a silver precipitate

clearly formed. The reaction mixture was filtered through a cross-over filter and the residue was evaporated to dryness. Then 50 ml of hexane was added to the residue and the mixture obtained was filtered. The precipitate on the filter was washed with 20 ml of hexane and the hexane fractions collected were boiled down until a light turbidity formed (about 35 ml). This turbid mixture was warmed up very mildly (35°C) and stored in a refrigerator at -20°C. After 17 hours crystals had formed. The whole was stored for another 20 hours at -80°C, after which the solid substance was filtered off and washed with 2 x 10 ml of cold (-20°C) hexane, Yield: 1.15 g of (N-t- butylamino) (dimethyl) (2,3, 5-tri-2- butylcyclopentadienyl)silane titanium dichloride.

Example II: the preparation of van (N-t- butylamino) (dimethyl ) (2 , 3 , 5-tri-2- pentylcyclopentadienyl)silane titanium dichloride

Example Ila: Preparation of di- and tri(2- pentyl )cvclopentadiene

A double-walled reactor having a capacity of 1 1 and provided with baffles, cooler, top stirrer, thermometer and dropping funnel was filled with 900 g (11.25 mol) of clear 50% NaOH. Then 31 g (77 mmol) of Aliquat 336 and 26.8 g (0.41 mol) of freshly cracked cyclopentadiene were added. The reaction mixture was vigorously stirred for several minutes. Then 155 g (1.03 mol) of 2-pentyl bromide were added in one hour. During this process, the mixture was cooled with water. After stirring for 3 hours at room temperature, the reaction mixture was heated to 70°C, after which stirring was carried out again for 2 hours. Stirring was stopped and phase separation was awaited. The water layer was drained off and 900 g (11.25 mol) of fresh 50% NaOH were added. Then stirring was carried out for

a further two hours at 70°C. It was demonstrated with GC that the mixture was composed of di- and tri (2- pentyl)cyclopentadiene (approximately 1:1) at that instant. The products were distilled at respectively 2 mbar, 79-81°C and 0.5 mbar, 102°C. After distillation, 28 g (0.136 mol; 33%) of di- and 40 g of tri(2- butyl)cyclopentadiene were obtained.

The characterization was carried out with the aid of GC, GC-MS, ¹³ C- and ^-NMR.

Example IIB: the preparation of van (N-t- butylamino) (dimethyl) ( 2 ,3,5-tri-2- pentylcyclopentadienyl)silane

In a 2-litre glass flask 19.4 g of tri(2- pentyl)cyclopentadiene (0.07 mol) was dissolved in 1 litre of dry THF with thorough stirring. This solution was cooled to 0°C by means of an ice bath. 43 ml of a 1.6M solution of butyl lithium in hexane (0.069 mol) was slowly added to the cooled solution. A light-yellow solution was obtained, which was stirred at room temperature for two hours. In approximately 4 hours' time this solution was added to a solution of 30.3 ml of dimethyldichlorosilane (0.25 mol) in 300 ml of dry THF in a 2-litre flask. A light-yellow solution formed, which was stirred for about three more hours at room temperature. Then the solvent and the excess of dimethyldichlorosilane were evaporated at 50°C and a 10 mm mercury pressure. The residue, a bright yellow liquid with some solid substance (LiCl), was added in about 1 hour's time to a solution of 37.5 ml of tertiary butylamine (0.35 mol) in 250 ml of dry THF in a 1-litre glass flask which was cooled by means of an ice bath. Then the ice bath was removed and the reaction mixture obtained was stirred for about 10 hours. The precipitate formed was filtered off through a Bϋchner funnel. The yellow filtrate was boiled down at 50°C and a 10 mm mercury pressure. Vacuum

distillation of the residue ultimately yielded 15.1 g of pure (N-t-butylamino) (dimethyl ) (2,3 , 5-tri-2- pentylcyclopentadienyl )silane.

Example IIC: the preparation of (N-t- butylamino) (dimethyl ) (2,3,5-tri-2- pentylcyclopentadienyl )silane titanium dichloride

Synthesis as that of (N-t- butylamino) (dimethyl ) (2 , 3 , 5-tri-2- butylcyclopentadienyl )silane titanium dichloride (example IC), now with:

2.9 g of (N-t-butylamino) (dimethyl) (2,3, 5-tri-2- pentylcyclopentadienyl )silane (7.15 mmol) 8.9 ml of a 1.6M solution of butyl lithium in hexane

(14.24 mmol); cooling of the dilithium compound -78°C hardly results in turbidity

2,65 g of titanium trichloride.3 THF (7.15 mmol)

1.03 g of silver chloride (7.2 mmol) recrystallization from about 20 ml of pentane instead of 35 ml of hexane yield: 0.71 g of (N-t-butylamino) (dimethyl) (2 , 3 , 5-tri-

2-pentylcyclopentadienyl)silane titanium dichloride.

Note: NMR showed that in the last filtrate (after recrystallization) quite a bit of product remained; this was not worked up.

Experiment a: the preparation of (N-t- butylamino) (dimethyl) (2,3,4,5- tetrametylcvclopentadienyl)silane titanium dichloride The synthesis of metal complexes was carried out in the manner as described for examples 1-4 of WO-

A-93/08221.

Polymerization examples III-VI and polymerization experiments A and B

The copolymerization of ethene with octene was carried out as follows:

600 ml of an alkane mixture (pentamethyl heptane or special boiling point gasoline) were supplied to a 1.5-litre stainless steel reactor under dry nitrogen as reaction medium. Then the envisaged amount of dry octene was introduced into the reactor.

Next the reactor was heated to the required temperature with stirring under the required ethene pressure.

25 ml of the alkane mixture as solvent were supplied to a 100-ml catalyst dispensing vessel. In this vessel the required amount of methylaluminoxane (MAO) was pre-mixed for 1 minute with the required amount of metal complex such that the Al/Ti ratio in the reaction mixture is equal to 2000.

This mixture was then supplied to the reactor and the polymerization started. The polymerization reaction was carried out isothermally. The ethylene pressure was kept constant at the set pressure. Upon completion of the required reaction time the ethene supply was stopped and the reaction mixture was drained off and quenched with methanol.

Next, an antioxidant (Irganox 1076®) was added to the organic fraction for the purpose of stabilization of the polymer. The polymer was dried under vacuum at 70°C for 24 hours. The following conditions were varied: metal complex - temperature

The actual conditions in each case are stated in the tables of polymerization conditions.

TABLE 1: C2/C8 polymerizations

ι

10

MAO: methylaluminoxane from Witco N.D. = not determined