Method for Preparation of a Ruthenium Indenylidene Complex

Abstract

The present invention is directed to a method for the preparation of ruthenium catalyst (PCy.sub.3).sub.2Cl.sub.2Ru(phenylindenylidene) (Umicore catalyst M1). The method comprises a one-step reaction reacting the precursor compound (PPh.sub.3).sub.2Cl.sub.2Ru(3-phenylindenylidene) with PCy.sub.3 in a cyclic ether solvent (preferably THF) in concentrations in the range of 0.2 to 0.6 mol catalyst/l while simultaneously precipitating the product from the reaction mixture.

A cyclic ether solvate product with high crystallinity and high purity is obtained.

Claims

1. A method for preparation of the ruthenium-indenylidene carbene catalyst of Formula 1, ##STR00008## said method comprising reacting (PPh.sub.3).sub.2Cl.sub.2Ru(3-phenylindenylidene) with tricyclohexyl-phosphine (PCy.sub.3) in a reaction mixture having a concentration in the range of 0.2 to 0.6 mol Ru-catalyst/l in a cyclic ether solvent and precipitating the resulting catalyst of Formula 1 during the reaction.

2. The method according to claim 1, wherein the catalyst of Formula 1 precipitates in the form of a crystalline cyclic ether solvate.

3. The method according to claim 2, wherein the cyclic ether solvate comprises >1 molecule of cyclic ether per molecule of catalyst.

4. The method according to any one of claims 1 to 3, wherein the cyclic ether solvent is selected from THF, methyl-THF, dimethyl-THF or mixtures thereof.

5. The method according to any one of claims 1 to 4, wherein the cyclic ether solvent is THF.

6. The method according to any one of claims 1 to 5, wherein the reaction temperature is in the range of 30 to 100 C., preferably in the range of 50 to 80 C.

7. The method according to any of claims 1 to 6, wherein the PCy.sub.3 is present in the range of 2 to 3 equivalents, preferably in the range of 2.1 to 2.5 equivalents.

8. The method according to any of claims 1 to 7, wherein the cyclic ether solvent may be partially distilled off during the reaction.

9. The method according to any one of claims 1 to 8, further comprising a cooling step, wherein the reaction mixture is cooled down to a temperature in the range of 30 to 25 C., preferably in the range of 0 to 25 C.

10. The method according to any one of claims 1 to 9, wherein the reaction time is in the range of 0.1 to 3 hours, preferably in the range of 0.5 to 2 hours.

11. The method according to any one of claims 1 to 10, further comprising steps of separating the resulting ruthenium-indenylidene catalyst from the reaction mixture.

12. The method according to any one of claims 1 to 10, further comprising steps for washing and drying the resulting ruthenium-indenylidene catalyst.

13. Ruthenium-indenylidene carbene catalyst obtainable by the method according to any one of claims 1 to 12, having a purity of >97%, preferably >99% and particularly preferred >99.5% (as determined by .sup.31P-NMR spectroscopy).

14. Ruthenium-indenylidene carbene catalyst obtainable by the method according to any one of claims 1 to 12, being present in a crystalline cyclic ether solvate form, comprising >1 molecule of cyclic ether per molecule of catalyst (as determined by .sup.1H-NMR and X-ray analysis).

15. Ruthenium-indenylidene carbene catalyst obtainable by the method according to claim 5, being present in a crystalline THF solvate form, comprising between 1 and 2 molecules of THF per molecule of catalyst (as determined by .sup.1H-NMR and X-ray analysis).

16. Ruthenium-indenylidene carbene catalyst of Formula 1, ##STR00009## being present in a crystalline THF solvate form and showing peaks at diffraction angles (2) in XRD powder diffractometry (CuX-ray tube, tube excitation 40 kV, 40 mA) as listed in the following table: TABLE-US-00003 Peak No. diffraction angle (2) a about 7.3 b about 8.7 c about 9.8 d about 11.8 e about 14.2 f about 14.6 g about 17.3 h about 17.9 i about 18.8 j about 20.3

Description

[0044] FIG. 1 shows the ORTEP plot of the single-crystal structure of M1 catalyst (THF-solvate) as determined by X-ray analysis. The crystallized complex comprises two co-crystallized THF molecules. The ellipsoids probability is shown at 50%, H-atoms are omitted. Space group is orthorhombic (Pca2(1)). Cell dimensions and angles: a=20.520(4), b=14.543(3), c=18.761(5); =90.00, =90.00, =90.00. The product crystallizes in dark red crystals.

[0045] A beneficial effect of the product crystallinity of the present invention is the ease with which the crystalline M1 material can be handled, filtered and washed. Product washing is necessary to remove PPh.sub.3 and other impurities generated in the reaction.

[0046] It has been found that the crystalline M1 product may loose some THF during washing, drying and further handling. However, the crystalline product obtainable by the method of the present invention comprises >1 molecule of cyclic ether per molecule of catalyst (as determined by X-ray analysis and .sup.1H-NMR spectroscopy). Preferably, the crystalline M1 product comprises between 1 and 2 molecules of THF per molecule of catalyst (as determined by X-ray analysis and .sup.1H-NMR spectroscopy).

[0047] The orange catalyst product which is state of the art (ref to the earlier cited preparation methods) comprises very fine needles. The orange form of the catalyst material produced according to standard methods is very bulky. In this form, the material is very difficult to filtrate, wash and to handle. The filtration time of the orange version is substantially prolonged, which in turn results in a product of low purity. It is likely that upon precipitation, the impurities are trapped in the orange version due to its flocculent form. The orange catalyst material is also more sensitive to the air oxygen since it has a larger specific surface area. As a consequence, it is much easier oxidized and it likely contains more phosphine oxides impurities unless it is rigorously stored under inert conditions.

[0048] According to the known procedures in the art, the desired bis-PCy.sub.3 complex may be obtained in acceptable purity only by using a large excess of PCy.sub.3 (typically in the range of 3 equivalents) which is not feasible from an industrial point of view due to the high cost of PCy.sub.3. Alternatively, the mixture of complexes is isolated and subjected to further treatment with PCy.sub.3. This is again not feasible at industrial scale because additional purification steps are needed.

[0049] The inventors have further observed that the known synthesis route A, which is the basis of the method of the present invention, basically yields a product which may contain variable amounts of the side product X (Ru complex with mixed substituents comprising a PCy.sub.3 and a PPh.sub.3 ligand) according to the following equation 3:

##STR00006##

[0050] Since the ligand exchange reaction is an equilibrium reaction, the skilled person would expect that a much less cleaner product would be obtained by working under high concentrations: as the reaction proceeds, the amount of PCy.sub.3 diminishes while the amount of liberated PPh.sub.3 grows; this leads to a mixture of starting material, product M1 and mixed complex X.

[0051] To the contrary, the inventors surprisingly found that when working with high concentrations in the range of c=0.2 to 0.6 mol catalyst/l, the product precipitates simultaneously from the reaction mixture so that it is removed from the reaction equilibrium, which is then shifted to the right side, thus affording the desired catalyst product M1 in very good yields and exceptional quality.

[0052] The catalyst produced according to the method of the invention is a crystalline material which shows high purity. The high purity is a direct consequence of the crystalline shape of the product.

[0053] Typically, the amount of impurity X in the M1 product made according to the invention is <3%, preferably <1% and most preferred <0.5% (based on the total weight of the catalyst product). The presence of mixed complex X in M1 will deteriorate its catalytic activity since it is known that the Ru-indenylidene complex bearing PPh.sub.3 groups is not metathesis active. This impurity X can be easily identified by .sup.31P-NMR as it displays two small peaks close to the product peak (when measured in CD.sub.2Cl.sub.2) or only one small peak (when measured in CDCl.sub.3).

[0054] For quantitative determination of purity, the peak integration method is employed. Based on the impurity data given above, the purity of the Ru-indenylidene catalyst prepared according to the invention is >97%, preferably >99% and particularly preferred >99.5% (as determined by .sup.31P-NMR spectroscopy).

[0055] FIGS. 2a-c, show the XRD diffractograms of three batches of catalyst Umicore M1 made according to the method of the present invention, which, according to .sup.1H-NMR analysis, contain different amounts of THF per mol Ru complex respectively:

[0056] FIG. 2a shows a XRD plot of M1 (red crystalline material, method of this invention, containing 1.54 mol THF per mol of complex),

[0057] FIG. 2b shows a XRD plot of M1 (red crystalline material, method of this invention, containing 1.4 mol THF per mol of complex),

[0058] FIG. 2c shows a XRD spectrum of M1 (red crystalline material, method of this invention, containing 1.1 mol THF per mol of complex).

[0059] FIG. 3a shows for comparative reasons a XRD diffractogram of the M1 catalyst made according to Umicore Standard Method (acc to WO2010/037550A1), which does not contain any THF (as confirmed by .sup.1H NMR). This product exhibited a bulk density of 0.3 g/ml.

[0060] FIG. 3b shows for comparative reasons a XRD diffractogram of the M1 catalyst made according to EP 2280033, Example 9, which contains less than 0.1 mol THF/mol product (as confirmed by .sup.1H NMR). This product exhibited a bulk density of 0.25 g/ml.

[0061] The detailed conditions for XRD measurements are given in the Examples section.

[0062] In general, the intensities of the peaks and the position of the peaks at various diffraction angles)(2 may slightly vary depending on the sample preparation, on the measurement conditions as well as on the THF content. The uncertainty in the peak position is +/0.05 2.

[0063] As a summary, from the analysis of the XRD diffractograms shown in FIGS. 2a-d vis-a-vis 3a and 3b, it is clearly evident that the M1 product made according to the method of the present invention displays a higher crystallinity and furthermore has a different constitution compared to the material available according to the prior art. The Umicore M1 obtained by the method of the present invention reveals characteristic peaks at various diffraction angles (2 values) as listed in Table 1. In this table, relative peak intensities are also listed. Moreover, it can be seen from the amorphous halo of the diffractograms in FIGS. 3a and 3b that the crystallinity of these compounds according to the prior art is lower than the crystallinity of the compounds obtained according to the subject patent application. Furthermore, the reflexes in 3a and 3b and their pattern are different from FIG. 2a-d.

[0064] In addition, a powder diffractogram was simulated (software XPert HighScore Plus of PANalytical) based on the crystal data of the single crystal analysis of the THF-solvate. It has been found that the simulated diffractogram is directly comparable to that one obtained experimentally with the material produced according to the present invention. The simulation confirms that Umicore M1 made according to the method of the present invention contains THF molecules in the crystal.

TABLE-US-00001 TABLE 1 Peak analysis of XRD diffractogram of Umicore M1 catalyst (made according to the method of the invention) Peak No. diffraction angle (2) rel. intensity*.sup.) a about 7.3 s b about 8.7 s c about 9.8 m d about 11.8 s e about 14.2 m f about 14.6 m g about 17.3 m h about 17.9 w i about 18.8 m j about 20.3 m *.sup.)relative peak intensities: s = strong; m = medium; w = weak

[0065] In FIG. 4, SEM pictures of two different batches of catalyst Umicore M1 are shown.

[0066] FIG. 4a shows M1 (red crystalline material, THF solvate, method of this invention).

[0067] FIG. 4b shows M1 (orange material, Umicore Standard method).

[0068] By these figure, the highly crystalline nature of the catalyst M1 made according to the method of the present invention is clearly demonstrated.

[0069] In summary, due to the preparation method of the present invention, the resulting Ru-indenylidene catalyst M1 reveals high product purity, in particular high crystallinity. As easily scaleable precipitation processes are employed, this preparation method is applicable to industrial production scale.

[0070] The Umicore M1 catalyst of the present invention is useful in a variety of olefin metathesis reactions such as ring-closing metathesis (RCM), ring-opening metathesis polymerization (ROMP) and cross metathesis (CM). Furthermore, it is a valuable precursor for the synthesis of other, further modified ruthenium carbene catalysts.

[0071] The present invention is directed to a method for the preparation of ruthenium catalyst (PCy.sub.3).sub.2Cl.sub.2Ru(phenylindenylidene) (Umicore catalyst M1). The method comprises a one-step reaction reacting the precursor compound (PPh.sub.3).sub.2Cl.sub.2Ru(3-phenylindenylidene) with PCy.sub.3 in a cyclic ether solvent (preferably THF) in concentrations in the range of 0.2 to 0.6 mol catalyst/l while simultaneously precipitating the product from the reaction mixture. A cyclic ether solvate product with high crystallinity and high purity is obtained.

[0072] The present invention is further directed to a crystalline modification of ruthenium catalyst Umicore M1 (PCy.sub.3).sub.2Cl.sub.2Ru(phenylindenylidene) comprising between 1 and 2 molecules of THF per molecule of catalyst and having the molecular formula C.sub.51H.sub.76Cl.sub.2P.sub.2Run(C.sub.4H.sub.8O) wherein 1n2.

[0073] The invention is further described in the following examples without restricting its scope of protection.

EXAMPLES

[0074] Generally, in the Examples glass reactors or flasks with condenser and stirrer are used for the method of the present invention. The reactors are flushed with dry inert gas (argon, nitrogen) prior to use.

[0075] The NMR spectra are recorded on a BRUKER DRX 500 NMR spectrometer at about 25 C. The chemical shifts are determined relative to external phosphoric acid (.sup.31P-NMR) or to residual solvent signal (.sup.1H-NMR).

[0076] The XRD diffractograms were recorded in the range 5<2<100 on a PANalytical X'Pert Pro with X-Celerator detector using Cu radiation. The sample material was prepared into a 27 mm PAN analytical sample holder (single preparation).

[0077] The XRD data were recorded under the following conditions:

TABLE-US-00002 Instrument PANalytical X'Pert Pro X-ray tube LFF-Cu-X-ray tube K-beta Filter Nickel Detector X'Celerator x-ray tube excitation 40 kV, 40 mA Divergence slit fixed Divergence slit size Anti-scatter slit 1 2-Theta range 5 to 100 Measurement Mode Continuous Time per step 40 s Step size 0.017 (2 Theta) Rotation 1 Rev/s
The uncertainty in the peak position is +/0.05 2.

Example 1

Preparation of starting complex (PPh.SUB.3.).SUB.2.Cl.SUB.2.Ru(3-phenylindenylidene) according to prior art (ref to H.-J. Schanz et al., cited above)

[0078] A one liter glass reactor with condenser and stirrer is filled with argon and thereafter with 800 ml of THF. The solvent is warmed up to 50 C. Then 19.7 g (98.6% purity, 93.2 mmol, 1.15 eq.) of 1,1-diphenyl-2-propyn-1-ol, 2.91 ml (40.5 mmol, 0.5 eq.; GFS Chemicals Inc., Powell, Ohio, USA) of acetylchloride and 99.6 g (81 mmol, 1 eq.) of Ru(PPh.sub.3).sub.3-4Cl.sub.2 (Ru-content 8.22 wt. %; Umicore AG & Co. KG, Hanau) are added successively during stirring. The reaction mixture is stirred under reflux (65 C.) for 90 min. Then it is cooled down to 50 C. and 700 ml of THF solvent are distilled off under vacuum. The red-brown suspension is cooled down to room temperature and isopropanol (600 ml) is added under stirring. The resulting precipitate is filtered off, washed with isopropanol and petroleum ether and then dried under vacuum at 40 C.

[0079] Yield: 85% (based on Ru-content).

[0080] .sup.31P-NMR (C.sub.6D.sub.6): =27.8 ppm (s)

Example 2

Preparation of dichloro(3-phenyl-1H-inden-1-ylidene)bis-(tricyclohexyl-phosphine)ruthenium(II) (according to the invention; c=0.5 mol/l)

[0081] ##STR00007##

[0082] A one liter glass reactor with condenser and stirrer is filled with argon and thereafter with 500 ml of THF. The solvent is warmed up to 40 C. Then 221.7 g (250 mmol, 1 eq.) of (PPh.sub.3).sub.2Cl.sub.2Ru(3-phenylindenylidene) (Umicore AG & Co. KG, Hanau) and 155 g (98.1% purity, 540 mmol, 2.16 eq.) of tricyclohexylphosphine (PCy.sub.3, Aldrich) are added successively with stirring. The reaction mixture is stirred under reflux (65 C.) for 1 h during which time the product precipitates in form of dark red crystals. The reaction mixture is cooled down to 5 C. The crystalline precipitate is filtered off, washed with 400 ml of acetone and then dried under vacuum at 80 C. Yield: 236 g, 88% (based on Ru-content 9.41 wt.-%).

[0083] .sup.31P-NMR (CD.sub.2Cl.sub.2): (ppm)=32.0 (s, product), 31.28 and 31.18 (side product).

[0084] Purity based on .sup.31P-NMR: >99%.

[0085] .sup.1H-NMR (CD.sub.2Cl.sub.2): (ppm)=8.66 (d, product, 1H), 7.96 (d, side product, <0.01H), 7.75 (m, product, 2H), 7.7 (m, side product, <0.02H), 7.52 (m, product, 1H), 7.40 (ms, product, 3H), 7.28 (m, product, 2H), 7.05 (td, side product, <0.01H), 7.016 (s, side product, <0.01H), 3.68 (m, THF, 6.4H), 2.60 (m, product, 6H), 1.9-1 (ms, product, 27H), 1.82 (m, THF, 6.4H). Other signals of the side product are covered by the signals of the product. THF-content based on .sup.1H-NMR=1.6 mol THF/mol product (11 wt.-%). Side-product content based on .sup.1H-NMR=<0.01 mol (<1 wt.-%).

[0086] Bulk density: 0.45 g/ml

[0087] Space yield: 236 g/l

Example 3

Preparation of dichloro(3-phenyl-1H-inden-1-ylidene)-bis-(tricyclohexyl-phosphine)ruthenium(II) (according to the invention; c=0.2 mol/l)

[0088] A one liter glass reactor with condenser and stirrer is filled with argon and thereafter with 600 ml of THF. Then 106.4 g (120 mmol, 1 eq.) of (PPh.sub.3).sub.2Cl.sub.2Ru(3-phenylindenylidene) (Umicore AG & Co. KG, Hanau) and 74 g (98.1% purity, 258 mmol, 2.15 eq.) of tricyclohexylphosphine, PCy.sub.3 are added successively with stirring. The reaction mixture is stirred under reflux (65 C.) for 0.5 hour. Then it is cooled down to 40 C. and 250 ml of THF solvent are distilled off causing the precipitation of the product in form of dark red crystals. Alternatively the solvent may be removed by a stream of inert gas during the reaction. The resulting red suspension is cooled down to 5 C. and acetone (500 ml) is added under stirring. The crystalline precipitate is filtered off, washed with acetone and then dried under vacuum at 80 C. Yield: 108 g, 85% (based on Ru-content, 9.54 wt.-%).

[0089] Purity (.sup.31P-NMR): >99%. The analytical data of the product are comparable to those of Example 2.

[0090] Space yield: 108 g/l

Comparative Example 4

Preparation of dichloro(3-phenyl-1H-inden-1-ylidene)-bis-(tricyclohexyl-phosphine)ruthenium(II) (according to EP 2280033, Example 9)

[0091] A 500 ml Schlenk flask was purged with argon for 15 minutes. 5.21 mmol (5.0 g) RuCl.sub.2(PPh.sub.3).sub.3 and 8.49 mmol (1.79 g) 1,1-diphenyl-2-propin-1-ol were placed into the flask. 267 ml absolute tetrahydrofurane were added and the reaction mixture was stirred at reflux for 3 hours. The mixture was evaporated by 50% in vacuum and 16.67 mmol (4.76 g) tricyclohexylphosphine were added. The suspension was stirred for 8 hours at room temperature under argon. Then the solvent was removed in vacuum. The oily residue was added with 135 ml of acetone. The mixture was stored for 10 hours at 20 C. The residue was filtered by suction filtration (nutsche filter, porosity D4). The solid was washed with methanol, acetone and hexane. The product was dried in vacuum at room temperature. The product was obtained as brick-red powder, 4.63 g (5.02 mmol, 87% yield on metal base).

[0092] Analysis

[0093] Bulk density: 0.25 g/ml

[0094] Space yield: about 14 g/L

[0095] Purity (.sup.31P NMR): about 80%.

[0096] THF-content (based on .sup.1H NMR, CD.sub.2Cl.sub.2, 20 C.): <0.1 mol THF/mol product (<0.5 wt.-%).

[0097] .sup.31P and .sup.1H-NMR data shows the presence of several side products: diphenylallenylidene complex ( 41 ppm in .sup.31P NMR) and phosphine oxides.