WO1997042149A1

WO1997042149A1 - Cyclopentadiene compound substituted with tertiary groups

Info

Publication number: WO1997042149A1
Application number: PCT/NL1997/000207
Authority: WO
Inventors: Gerardus Johannes Maria Gruter; Johannes Antonius Maria Van Beek; Henricus Johannes Arts; Ramon Hubertus Anna Maria Meijers
Original assignee: Dsm N.V.
Priority date: 1996-05-03
Filing date: 1997-04-22
Publication date: 1997-11-13
Also published as: AU2578697A; NL1003014C2

Abstract

Substituted cyclopentadiene compound in which the cyclopentadiene compound is at least bisubstituted and in which at least one substituent is a tertiary alkyl group.

Description

CYCLOPENTADIENE COMPOUND SUBSTITUTED WITH TERTIARY GROUPS

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. In J. of Organomet. Chem., 479 (1994), 1-29 an overview is provided of the influence of the substituents on cyclopentadiene as a ligand in metal complexes. Here it is observed, on the one hand, that the chemical and physical properties of metal complexes can be varied over a wide range by the specific choice of the substituents on the cyclopentadiene ring. On the other hand, it is stated that no predictions can be made concerning the effect to be expected of specific substituents. Hereinafter, 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. A drawback of the known substituted Cp compounds is that, while they do impart a certain stability to the metal complex when they are used as ligand in a metal complex, at higher temperatures the stability of these complexes decreases faster than is desirable. The object of the invention is to provide substituted Cp compounds which, when applied as ligand in a metal complex, give the metal complex a better resistance to higher temperatures than do the known Cp compounds. This object is achieved, according to the invention, in that the Cp compound is at least bisubstituted and at least one of the substituents is a tertiary alkyl group.

The presence of at least one tertiary alkyl group instead of hydrogen or methyl groups in a metal complex is found to lead to a better resistance to higher temperatures than when use is made of other Cp compounds applied as ligand. A tertiary group as substituent is here understood to mean a group in which a tertiary carbon atom is present which is bound directly to the Cp.

It is also possible for several tertiary alkyl groups to be present as substituents. These may be either the same or different. Examples of suitable tertiary substituents are 1, 1-dimethylpropyl , 1 , 1-dimethylbutyl , 1,1- dimethylpentyl , 1 , 1-dimethylhexyl , 1-methyl-l- ethylpropyl, 1-methyl-l-ethylbutyl , 1-methyl-l- ethylpentyl, 1-methyl-l-ethylhexyl , 1 , 1-diethylpropyl , 1 , 1-diethylbutyl , 1 , 1-diethylpentyl , 1 , 1-diethylhexyl. Preferably, two or three tertiary alkyl groups are substituted on the Cp compound according to the invention. Metal complexes with the thus substituted Cp compound as ligand prove to exhibit a higher activity in the polymerization of α-olefines than in case the Cp compound is monosubstituted with a tertiary alkyl group. Besides the tertiary alkyl group that is required as substituent for the compound according to the invention, at least one other group is substituted at another position of the Cp. These groups may be chosen from, for example alkyl groups, linear as well as branched and cyclic ones, alkenyl and aralkyl groups. Further, besides carbon and hydrogen also one or more hetero atoms from groups 14-17 of the Periodic System may be present, for example O, N, Si or F, in which a hetero atom is not bound directly to the Cp. Examples of suitable other groups are methyl, ethyl, (iso)propyl, secondary butyl, secondary pentyl, secondary hexyl and secondary octyl, (tertiary) butyl and higher homologues, cyclohexyl, benzyl. For the Periodic System, 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.

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.

The term olefins here and hereinafter refers to α-olefins, diolefins and other ethylenically unsaturated monomers. Where the term 'polymerization of olefins' is used, this hereinafter refers both to the polymerization of a single type of olefinic monomer and to the copolymerization of two or more olefins.

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. The term Cp compounds refers to Cp itself and Cp already substituted at at least one position, with the option of two substituents forming a closed ring. By means of the process described hereinafter it is thus possible to convert unsubstituted compounds into mono- or poly- substituted ones, but it is also possible for mono- or polysubstituted compounds derived from Cp to be substituted further, after which ring closure is also possible.

Use can be made of a virtually equivalent quantity with respect to the Cp-compound of the halogenated substituting compound. An equivalent quantity is understood to be a quantity in moles which corresponds to the desired substitution multiplicity, for example 2 moles 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 compound 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 susbtituting compound it is generally possible to achieve tetra- and often even pentasubstitution.

The substituents are preferably used in the process 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 process 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, 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 5-60 moles, preferably 6-30 moles, per mole of Cp compound. It was found that the reaction time can be considerably shortened if the solution of the base is refreshed, for example by first mixing, the solution with the other components of the reaction mixture and after some time separating the aqueous phase and replacing it by a fresh quantity of the solution of the base. The substitution takes place at atmospheric or elevated pressure, for example up to 100 MPa, the latter especially when volatile components are present. The temperature at which the reaction takes place can vary between wide limits, for example from -20 to 120°C, preferably between 10 and 50°C. Initiating the reaction at room temperature is suitable, as a rule, whereupon the temperature of the reaction mixture may rise as a result of the heat liberated in the course of the reaction occurring.

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 the OH-ions reacting in the organic phase with a H-atom which can be split off from the Cp compound. The organic phase contains the Cp compound and the substituting compound. As phase transfer catalysts use can be made of quaternary ammonium, phosphonium, arsonium, antimony, bismuthonium, and tertiary sulphonium salts. More preferably, ammonium and phosphonium salts are used, for example tricapryl- methylammonium chloride, commercially available under the name Aliquat 336 (Fluka AG, Switzerland; General Mills Co., USA) and Adogen 464 (Aldrich Chemical Co., USA). Compounds such as benzyl-triethylammonium chloride (TEBA) or benzyltriethyl-ammonium bromide (TEBA-Br), benzyltrimethylammonium chloride, benzyltrimethylammonium bromide or benzyl-trimethyl¬ ammonium hydroxide (Triton B), tetra-n-butylammonium chloride, tetra-n-butylammonium bromide, tetra-n-butyl- ammonium iodide, tetra-n-butylammonium hydrogen sulphate or tetra-n-butylammonium hydroxide and cetyltrimethylammonium bromide or cetyltrimethyl¬ ammonium chloride, benzyltributyl-, tetra-n-pentyl-, tetra-n-hexyl- and trioctylpropylammonium chlorides and their bromides are likewise suitable. Usable phosphonium salts are, for example, tributylhexa- decylphosphonium bromide, ethyltriphenylphosphonium bromide, tetraphenylphosphonium chloride, benzyl¬ triphenylphosphonium iodide and tetrabutylphosphonium chloride. Crown ethers and cryptands can also be used as a phase transfer catalyst, for example 15-crown-5, 18-crown-6, dibenzo-18-crown-6 , dicyclohexano-18-crown- 6 , 4 , 7 , 13 , 16,21-pentaoxa-l,10-diazabicyclo-[ 8.8.5]- tricosane (Kryptofix 221), 4 , 7, 13 , 18-tetraoxa-l, 10- diazabicyclo[8.5.5]eicosane (Kryptofix 211) and

4,7,13,16,21 ,24-hexaoxa-l, 10-diazabicyclo[ 8.8.8]-hexa- cosane ("[2.2.2]") and its benzo derivative Kryptofix 222 B. Polyethers such as ethers of ethylene glycols can also be used as a phase transfer catalyst. Quaternary ammonium salts, phosphonium salts, phosphoric acid triamides, crown ethers, polyethers and cryptands can also be used on supports such as, for example, on a crosslinked polystyrene or another polymer. The phase transfer catalysts are used in an amount of 0.01 - 2, preferably 0.05 - 1, equivalents on the basis of the amount of Cp compound. In the implementation of the process the components can be added to the reactor in various sequences.

After the reaction is complete, the aqueous phase and the organic phase which contains the Cp compound are separated. When necessary, the Cp compound is recovered from the organic phase by fractional distillation.

The substituted Cp compounds according to the invention are particularly suitable for incorporation as a ligand in a metal complex, and then bring about the favourable effect [set out] in the preceding that the complex is better resistant to higher temperatures than are complexes containing the known Cp ligands. The invention therefore also relates to a metal complex in which at least one cyclopentadiene compound substituted with at least one tertiary alkyl group is present as ligand.

It has further been found that, when used as a ligand in a metal complex, a bi- or polysubstituted Cp compound in which at least one of the substituents is a tertiary alkyl group yields a complex which, when used as a catalyst component in the polymerization of α-olefins, yields a catalyst that has a higher activity than can be obtained with known Cp compounds if at least one other substituent on the Cp compound has the form -RDR'_n, where R is a linking group between the Cp and the DR'_n group, D is a hetero atom chosen from group 15 or 16 of the Periodic System of the Elements or an aryl group, R' is a substituent and n the number of R' groups bound to D. This holds in particular if the metal in the complex is not in the highest valency state. Transition metal complexes in which the metal is not in the highest valency state but in which the Cp ligand does not contain a group of the form RDR'n are, as a rule, entirely inactive in olefin polymerizations. The overview article in J. of Organomet. Chem. from 1994 referred to earlier even concludes that 'An important feature of these catalyst systems is that tetravalent Ti centres are required for catalytic activity'. It should be noted that Ti serves as an example of the metals that are suitable for use as metal in the customary cyclopentadenyl-substituted metal complexes.

Similar complexes, in which the Cp compound is not substituted in the indicated manner, prove to be unstable or, if they are stabilized in another way, yield less active catalysts than the complexes with substituted Cp compounds according to the invention, in particular in the polymerization of α-olefins.

Further, the Cp compounds according to the invention are found to be capable of stabilizing highly reactive intermediates such as organometal hydrides, organometal boron hydrides, organometal alkyls and organometal cations. In addition, they are found to be suitable as stable and volatile precursors for use in Metal Chemical Vapour Deposition. The invention therefore also relates to Cp compounds thus further substituted.

From Synthesis, 1993, 684-686, tetramethyl- cyclopentadiene is known, with ethyldimethylamine as fifth substituent. In no way can the stabilizing effect of the presence of the further substituted Cp compounds according to the invention as ligands in metal complexes be derived from this publication. For the preparation of this further substituted Cp compound, a group of the form -RDR'_n can be substituted on a Cp compound substituted with at least one tertiary alkyl group. The R group forms the link between the Cp and the DR'_n group. The length of the shortest link between the Cp and D is critical to the extent that, if the Cp compound is used as ligand in a metal complex, it is decisive for the accessibility of the metal by the DR'„ group in order thus to achieve the desired intramolecular coordination. An unduly short length of the R group (or bridge) may cause the DR'_n group to be unable to coordinate well as a result of ring tension. The length of R is at least one atom. The R' groups may each separately be a hydrocarbon radical containing 1 - 20 carbon atoms (such as alkyl, aryl, arylalkyl and the like). Examples of such hydrocarbon radicals are methyl, ethyl, propyl, butyl, hexyl, decyl, phenyl, benzyl and p-tolyl. R' may also be a substituent which contains one or more hetero atoms from groups 14 - 16 of the Periodic System of the Elements in addition to or instead of carbon and/or hydrogen. Thus, a substituent may be a group containing N, 0 and/or Si. R' must not be a cyclopentadienyl group or a group derived therefrom.

The R group may be a hydrocarbon group containing 1 - 20 carbon atoms (such as alkylidene, arylidene, arylalkylidene and the like). Examples of such groups are methylene, ethylene, propylene, butylene, phenylene, optionally having a substituted side chain. Preferably, the R group has the following structure:

⁽-ER² -⁾,

where p = 1 - 4 and E is an atom from group 14 of the Periodic System. The R² groups may each be H or a group as defined for R'.

The main chain of the R group may thus contain silicon or germanium besides carbon. Examples of such R groups are: dialkylsilylene, dialkyl- germylene, tetra-alkyldisilylene or dialkylsilaethylene (-(CH₂) (SiR² ₂)-) . The alkyl groups (R²) in such a group preferably have 1 - 4 C atoms and are, more preferably, a methyl or ethyl group.

The DR'_n group comprises a hetero atom D chosen from group 15 or 16 of the Periodic System of the Elements and one or more substituent (s) R' bound to D. The number of R' groups (n) is coupled to the nature of the hetero atom D in such a fashion that n = 2 if D originates from group 15 and that n = 1 if D originates from group 16. Preferably, the hetero atom D is chosen from the group comprising nitrogen (N) , oxygen (O) , phosphorus (P) or sulphur (S); more preferably, the hetero atom is nitrogen (N). The R' group is also preferably an alkyl, more preferably an n-alkyl group containing 1 - 20 C atoms. More preferably, the R' group is an n-alkyl containing 1 - 10 C atoms. Another possibility is that two R' groups in the DR'_n group are joined to each other to form a ring-type structure (so that the DR'_n group may be a pyrrolidinyl group). The DR'_n group may bond coordinatively to a metal.

Subsequent substitution of an RDR'_n group as described above on a Cp compound already substituted with at least one tertiary alkyl group can, for example, take place according to the following synthesis route.

During a first step of this route, a substituted Cp compound is deprotonated by reaction with a base, sodium or potassium.

As base, use may be made, for example, of organolithium compounds (R³Li) or organomagnesium compounds (R³MgX), where R³ is an alkyl, aryl or aralkyl group and X is a halide, for example n-butyllithium or isopropylmagnesium 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.

Said reaction can be carried out in a polar dispersant, for example an ether. Examples of suitable ethers are tetrahydrofuran (THF) or dibutyl ether. Apolar solvents, such as, for example, toluene can also be used.

Subsequently, during a second step of the synthesis route, the cyclopentadienyl anion formed reacts with a compound of the formula (R'_nD-R-Y) or (X- R-Sul ) , where D, R, R' and n are as defined previously. Y is a halogen atom (X) or a sulphonyl group (Sul).

The halogen atom X may be chlorine, bromine and iodine. The halogen atom X preferably is a chlorine or bromine atom. The sulphonyl group has the form -OS0₂R⁶, wherein R⁶ is a hydrocarbon radical containing 1 - 20 carbon atoms, such as alkyl, aryl, aralkyl. Examples of such hydrocarbon radicals are butane, pentane, hexane, benzene and naphthalene. R⁶ may also contain one or more hetero atoms from groups 14 - 17 of the Periodic System of the Elements, such as N, 0, Si or F, in addition to or instead of carbon and/or hydrogen. Examples of sulphonyl groups are: phenylmethanesulphonyl, benzenesulphonyl, 1-butane- sulphonyl, 2,5-dichlorobenzenesulphonyl, 5-dimethyl- amino-1-naphthalenesulphonyl, pentafluorobenzene- sulphonyl, p-toluenesulphonyl, trichloromethane- sulphonyl, trifluoromethanesulphonyl, 2,4,6-triiso- propylbenzenesulphonyl, 2,4,6-trimethylbenzene- sulphonyl, 2-mesitylenesulphonyl, methanesulphonyl, 4-methoxybenzenesulphonyl, 1-naphthalenesulphonyl, 2-naphthalenesulphonyl, ethanesulphonyl, 4-fluoro- benzene-ulphonyl and 1-hexadecanesulphonyl. Preferably, the sulphonyl group is p-toluenesulphonyl or trifluoro- methanesulphonyl.

If D is a nitrogen atom and Y is a sulphonyl group, the compound according to the formula (R'_nD-R-Y) is formed in situ by reaction of an aminoalcohol compound (R'₂NR-OH) with a base (such as described above), potassium or sodium, followed by a reaction with a sulphonyl halide (Sul-X).

The second reaction step can also be carried out in a polar solvent as described for the first step. The temperature at which the reactions are carried out is between -60 and 80°C. Reactions with X-R-Sul and with R'_nD-R-Y in which Y is Br or I are usually carried out at a temperature between -20 and 20°C. Reactions with DR'_n-R-Y in which Y is Cl are usually carried out at a higher temperature (10 to 80°C). The upper limit for the temperature at which the reactions are carried out is determined in part by the boiling point of the compound DR'_n-R-Y and that of the solvent used.

After the reaction with a compound of the formula (X-R-Sul) another reaction is carried out with LiDR'_n or HDR'_n in order to replace X by a DR'_n functionality. This reaction is carried out at 20 to 80°C, optionally in the same dispersant as mentioned above. During the synthesis process according to the invention, no geminal products are formed.

Metal complexes in which at least a cyclo¬ pentadiene compound as defined above is present are found to have an improved stability compared with such complexes in which other Cp compounds are present as ligand, in particular when the metal in the complex is not in its highest valency state. In addition, such complexes require less cocatalyst, as described above, the invention therefore relates also to said metal complexes and their use as catalyst component for the polymerization of olefins.

Metal complexes that are catalytically active if one of their ligands is a compound according to the invention, are the same as specified in the aforegoing.

The synthesis of metal complexes containing the above-described specific Cp compounds as a ligand may take place according to the processes known per se for this purpose. The use of these Cp compounds does not require any adaptations of said known processes.

The polymerization of α-olefins, for example ethylene, propylene, 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 ligand. Suitable in particular for this purpose are the complexes of transition metals, which are not in their highest valency state, in which just one of the cyclopentadienyl compounds according to the invention is present as ligand and in which the metal is cationic during the polymerization. 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. Examples are trialkylaluminium, alkyl- aluminium halides, alkylalumino-oxanes (such as methylaluminoxanes) , tris(pentafluoro-phenyl) borate, dimethylanilinium tetra(penta-fluorophenyl) 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.

Gas chromatography was performed on a Hewlett Packard 5890 Series II with an HP Crosslinked Methyl Silicon Gum (25 m x 0.32 mm x 1.05 μm) column. Gas chromatography combined with mass spectrometry (GC-MS) was performed with a Fisons MD800, equipped with a quadrupole mass detector, Fisons AS800 autoinjector and CPSil8 column (30 m x 0.25 mm x 1 μm, low bleed). NMR was performed with a Bruker ACP200 (^XH = 200 MHz; ¹³C = 50 MHz) or Bruker ARX400 NMR (^XH = 400 MHz; ¹³C = 100 MHz). Metal complexes were characterized using a Kratos MS80 mass spectrometer or a Finnigan Mat 4610 mass spectrometer.

Example I Preparation of di(1,l-dimethyl-propyl)cyclopentadiene A double-walled reactor having a volume of 1 L, provided with baffles, condenser, top stirrer, thermometer and dropping funnel, was charged with 600 g of clear 50% strength NaOH (7.5 mol), followed by cooling to 8°C. Then 20 g of Aliquat 336 (49 mmol) and 33 g (0.5 mol) of freshly cracked cyclopentadiene were added. The reaction mixture was stirred turbulently for a few minutes. Then 226.6 g of 2-bromo-2-methylbutane (1.05 mol) was added in one operation, cooling with water taking place at the same time. After 2 hours' stirring at room temperature the reaction mixture was heated to 70°C, followed by a further 6 hours' stirring. GC was used to show that at that instant 56% of di (1 , 1-dimethyl-propyl)cyclopentadiene was present. The product was distilled at low pressure and high temperature, after which 47.7 g (0.23 mol; 46%) of di (1 , 1-dimethyl-propyl)cyclopentadiene was obtained. Characterization took place with the aid of GC , GC-MS, ¹³C- and ^XH-NMR.

Example II Preparation of di-(1-methyl-l-ethyl-propyl ) cyclopentadiene

This preparation was carried out as in

Example I, but now use was made of:

247.6 g of 2-bromo-2-ethyl-butane. Initially 55%, and after distillation 43% (50.4 g) of di (1-methyl-l-ethyl- propyl )cyclopentadiene was obtained.

Experiment III

In-situ preparation of 2-(N,N-dimethylaminoethyl ) tosylate

A solution of n-butyllithium in hexane (1 equivalent) was added at -10°C (dispensing time: 60 minutes) to a solution of 2-dimethylaminoethanol (1 equivalent) in dry THF under dry nitrogen in a three- neck round-bottom flask provided with a magnetic stirrer and a dropping funnel. After all the butyl- lithium had been added, the mixture was brought to room temperature and stirred for 2 hours. The mixture was then cooled (-10°C), after which paratoluene-sulphonyl chloride (1 equivalent) was added. The solution was then stirred for 15 minutes at this temperature before it was added to a cyclopentadienyl anion.

Comparable tosylates can be prepared in an analogous way. In a number of the examples below, a tosylate is always coupled to alkylated Cp compounds. During this coupling, no geminal coupling takes place. Exampl e IV a. Preparation of (dimethylaminoethyi )di (1, 1- dimethylpropyl )cvclopentadiene

25 mL of a 1.6 molar solution of n-butyl- lithium in hexane was added dropwise to a cooled (0°C) solution of di (1 , 1-dimethylpropyl )cyclopentadiene (8.25 g; 40 mmol) in dry tetrahydrofuran (125 ml) under a nitrogen atmosphere in a 250 ml three-neck round-bottom flask provided with magnetic stirrer and dropping funnel. After stirring for 24 hours at room temperature, a solution of the 2-(dimethylaminoethyi )- tosylate (40 mmol) in THF/hexane (see Example IB) was added. After stirring for 18 hours, the conversion was found to be 91% and water (100 mL) was carefully added dropwise to the reaction mixture, after which the tetrahydrofuran was distilled off. The crude product was extracted with ether, after which the combined organic phase was dried (sodium sulphate) and evaporated down. The residue was purified by means of a column containing silica gel resulting in 9.1 g (82%) of (dimethylaminoethyi )di (1 , 1-dimethylpropyl )cyclo¬ pentadiene.

a. Synthesis of (dimethylaminoethyi )di (1 , 1- dimethylpropyl)cyclopentadienyl )titanium dichloride At 0°C (ice bath) 3.1 mL of a 1.6 molar butyllithium in hexane solution was added to (dimethylaminoethyi)di (1 , 1-dimethylpropyl)cyclo¬ pentadiene (1.39 g, 5 mmol), dissolved in 20 mL of tetrahydrofuran. After 15 minutes' stirring this mixture was cooled down further to -78 degrees Celsius and a slurry, also cooled to -78 degrees Celsius, of Ti(III)Cl₃.3THF (1.86 g, 5 mmol) in 20 mL of THF was added. The cooling bath was removed and the dark green solution formed was stirred for 72 hours at room temperature. After evaporation, 30 mL of petroleum ether (40-60) was added. Complete evaporation was again carried out, yielding a green powder (2.20 g) containing ( (dimethylaminoethyi )di (1, 1-dimethyl¬ propyl )cyclopentadienyl )titaniumdichloride.

Example V a. Preparation of (dimethylaminomethyl )di (1-methyl-l- ethyl-propyl )cyclopentadiene

The preparation was carried out as in Example IV, but now use was made of 7.03 g of di (1-methyl-l- ethyl-propyl)cyclopentadiene (30 mmol), 30 mol of 2- (dimethylaminoethyl )tosylate and 18.7 mL of 1.6 M butyllithium solution. Initially 90%, and after distillation over the column 79% (7.24 g) of (dimethyl¬ aminomethyl )di (1-methyl-l-ethyl-propyl )cyclopentadiene was obtained.

b. Synthesis of (dimethylaminomethyl )di (1-methyl-l- ethyl-propyl ) cyclopentadienyl )titaniumdichloride

The synthesis was carried out as in Example IV, but now use was made of: 1.53 g of (dimethylamino¬ methyl )di (1-methyl-l-ethyl-propyl )cyclopentadiene. 3.1 g of compound was obtained containing ( (dimethylamino¬ ethyi )di (1-methyl-l-ethyl-propyl )cyclopentadienyl )- titaniumdichloride.

Comparative Experiment A

Synthesis of ( (dimethylaminomethyl Cyclopenta¬ dienyl )titaniumdichloride

The synthesis was carried out as in Example IV, but now use was made of 1.37 g of (dimethylamino¬ ethyi) cyclopentadiene (10 mmol), 6.2 mL of a 1.6 molar butyllithium solution in hexane and 3.7 g of TiCl₃.3THF (10 mmol). 2.6 g of compound was obtained containing ( (dimethylaminoethyi )cyclopentadienyl )titaniumdi- chloride. Examples VI-IX and Comparative Experiments B and C Ethylene/octene copolymerization

The copolymerizations of ethylene with octene were carried out in the following way. 600 mL of an alkane mixture (pentamethyl- heptane or special boiling point solvent) was intro¬ duced into a 1.5 L stainless steel reactor under dry N2 as reaction medium. Subsequently, the desired amount of dry octene was introduced into the reactor. The reactor was then heated to the desired temperature under a desired ethylene pressure while stirring was applied.

25 mL of the alkane mixture was fed as solvent to a 100 mL catalyst dosing vessel. In this vessel, the desired amount of an Al-containing cocatalyst was premixed with the desired amount of metal complex for 1 minute.

This mixture was then dosed to the reactor, upon which the polymerization started. The polymerization reaction thus started was carried out isothermally. The ethylene pressure was kept constant at the set pressure. After the desired reaction time the ethylene feed was stopped and the reaction mixture was drained and quenched with methanol.

The reaction mixture with methanol was washed with water and HCI so as to remove catalyst residues. Subsequently, the mixture was neutralized with NaHC0₃. Then an antioxidant (Irganox 1076, TM) was added to the organic fraction to stabilize the polymer. The polymer was dried under a vacuum at 70°C during 24 hours.

Capable of variation are:

- metal complex

- temperature

The actual conditions are presented in Table I. Table i

KO I

10

* MAOi methylalumlnoxane, Wltco

Claims

C L A I M S

1. Substituted cyclopentadiene compound, characterized in that the cyclopentadiene compound is at least bisubstituted and at least one substituent is a tertiary alkyl group.

2. Substituted cyclopentadiene compound, according to claim 1, in which 2 substituents are tertiary alkyl groups.

3. Substituted cyclopentadiene compound, according to claim 1, in which 3 substituents are tertiary alkyl groups.

4. Substituted cyclopentadiene compound according to claim 1, in which at least one substituent has the form -RDR'_n, where R is a linking group between the cyclopentadiene and the DR'_n group, D is a hetero atom chosen from group 15 or 16 of the Periodic System of the Elements, R' is a substituent and n the number of R' groups bound to D, and in which at least one of the other substituents is a tertiary alkyl group.

5. Substituted cyclopentadiene compound, according to claim 4, in which R has the structure

(-ER² ₂-)_p where p = 1-4 and E is an atom from group 14 of the Periodic System.

6. Substituted cyclopentadiene compound according to any one of claims 4-5, in which D is chosen from the group comprising nitrogen (N) , oxygen (0), phosphorus (P) or sulphur (S).

7. Substituted cyclopentadiene compound according to any one of claims 4-6, in which R' is an N-alkyl group containing 1-20 carbon atoms.

8. Metal complex in which at least one cyclopentadiene compound according to any one of claims 1-7 is present as a ligand.

9. Metal complex in which the complex contains a metal that is not in its highest valency state and at least one cyclopentadiene compound according to any one of claims 4-7.

10. Use of the metal complex according to claim 8 or 9 as catalyst component for the polymerization of α- olefins.