Mcconville, David H. (Houston, TX, US)
Ackerman, Lily (San Francisco, CA, US)
Li, Robert T. (Houston, TX, US)
Bei, Xiaohong (Oak Park, CA, US)
Kuchta, Matthew C. (Heidelberg, DE)
Boussie, Tom (Menlo Park, CA, US)
Walzer Jr., John F. (Seabrook, TX, US)
Diamond, Gary (San Jose, CA, US)
Rix, Francis C. (League City, TX, US)
Hall, Keith A. (San Jose, CA, US)
Lapointe, Anne (Sunnyvale, CA, US)
Longmire, James (San Jose, CA, US)
Murphy, Vince (San Jose, CA, US)
Sun, Pu (San Jose, CA, US)
Verdugo, Dawn (San Francisco, CA, US)
Schofer, Susan (San Francisco, CA, US)
Dias, Eric (Belmont, CA, US)

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ExxonMobil Chemical Patents Inc. (Houston, TX, US)

502/168

502/103, 502/167, 585/511, 585/513

C07C2/26; C07C2/32; B01J31/02

502/168, 502/103, 502/167, 585/511, 585/513

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AT237622	May, 2003
AU594749	September, 1987
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AU735915	January, 1999
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BR8701145	January, 1988
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CN1011693	September, 1987
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EP0622347	November, 1994			Ethylene trimerisation and catalysts therefor
EP0668106	August, 1995			Olefin production.
EP0706983	April, 1996			Process for producing alpha-olefin oligomers
EP0537609	August, 1996			Ethylene oligomerization
EP0416304	March, 1997			Chromium compounds and uses thereof.
EP0614865	October, 1997			Process for producing olefins having a terminal double bond
EP0699648	April, 1998			Process for producing 1-hexene
EP0889061	January, 1999			Catalyst composition for the polymerization of olefins
EP0780353	August, 2000			Process for the oligomerisation of olefins
EP0608447	October, 2001			Process for the preparation of a catalyst for olefin polymerization
EP0993464	April, 2003			CATALYST FOR THE PRODUCTION OF OLEFIN POLYMERS
EP1308450	May, 2003			Titanium substituted pyridyl amine complexes, catalysts and processes for polymerizing ethylene and styrene
EP1110930	September, 2003			Catalytic composition and process for the oligomerisation of ethylene, to primarily 1-hexene
EP1364974	November, 2003			Substituted pyridyl amine ligands, complexes, catalysts and processes for polymerizing and polymers
FI8701125	September, 1987
GB2298864	September, 1996
HU44049	January, 1988
HU201785	January, 1988
IL81821	September, 1990
IN168364	March, 1991
JP4066457	November, 1987
JP62265237	November, 1987
JP7010780	January, 1995
JP06515873	March, 1995
JP07215896	August, 1995			PRODUCTION OF ALPHA-OLEFIN OLIGOMER
JP07267881	October, 1995			PRODUCTION OF OLEFIN HAVING DOUBLE BOND AT MOLECULAR CHAIN TERMINAL
JP09020692	January, 1997			TRIMERIZATION OF ETHYLENE
JP09020693	January, 1997			TRIMERIZATION OF ETHYLENE
JP09268133	October, 1997			PRODUCTION OF 1-HEXENE
JP09268134	October, 1997			PRODUCTION OF 1-HEXENE
JP09268135	October, 1997			PRODUCTION OF 1-HEXENE
JP10007593	January, 1998			PRODUCTION OF 1-HEXENE
JP10007594	January, 1998			PRODUCTION OF 1-HEXENE
JP10007595	January, 1998			PRODUCTION OF 1-HEXENE
JP10007712	January, 1998			PRODUCTION OF ALPHA-OLEFIN OLIGOMER
JP10036431	February, 1998			ETHYLENE TRIMERIZATION CATALYST AND METHOD FOR TRIMERIZING ETHYLENE THEREWITH
JP10036432	February, 1998			ETHYLENE TRIMERIZATION CATALYST AND METHOD FOR TRIMERIZING ETHYLENE THEREWITH
JP10045638	February, 1998			PRODUCTION OF 1-HEXENE
JP10087518	April, 1998			PRODUCTION OF 1-HEXENE
JP3491761	January, 1999
JP2001524162	January, 1999
JP11092407	April, 1999			CATALYST FOR TRIMERIZING ETHYLENE AND TRIMERIZATION OF ETHYLENE IN PRESENCE OF THE SAME
JP11092408	April, 1999			CATALYST FOR TRIMERIZING ETHYLENE AND TRIMERIZATION OF ETHYLENE IN PRESENCE OF THE SAME
JP11222445	August, 1999			PRODUCTION OF ALPHA-OLEFIN OLIGOMER
JP2000176291	June, 2000			CATALYST FOR TRIMERIZATION REACTION OF ETHYLENE, AND METHOD OF TRIMERIZATION REACTION OF ETHYLENE USING THE SAME
JP2000202299	July, 2000			ETHYLENE TRIMERIZATION CATALYST AND METHOD FOR TRIMERIZING ETHYLENE USING SAME
JP2000212212	August, 2000			ETHYLENE TRIMERIZATION CATALYST AND TRIMERIZATION OF ETHYLENE IN THE PRESENCE OF THE SAME
JP2001009290	January, 2001			TRIMERIZATION CATALYST OF ETHYLENE AND METHOD FOR TRIMERIZATION OF ETHYLENE USING THE SAME
JP2001187345	July, 2001			CATALYST COMPONENT FOR TRIMERIZING ETHYLENE, TRIMERIZING CATALYST AND METHOD FOR TRIMERIZING ETHYLENE USING THE SAME
JP2002045703	February, 2002			ETHYLENE TRIMERIZATION CATALYST AND METHOD FOR TRIMERIZING ETHYLENE USING THE SAME
JP2002066329	March, 2002			ETHYLENE TRIMERIZATION CATALYST AND METHOD FOR TRIMERIZING ETHYLENE USING THE SAME
JP2002102710	April, 2002			ETHYLENE TRIMERIZATION CATALYST AND METHOD FOR TRIMERIZING ETHYLENE USING THE SAME
JP2002172327	June, 2002			TRIMERIZATION CATALYST OF ETHYLENE AND METHOD FOR TRIMERIZING ETHYLENE USING THE SAME
JP2002200429	July, 2002			CATALYST FOR TRIMERIZING ETHYLENE AND METHOD FOR TRIMERIZING ETHYLENE BY USING THE SAME
JP2002205960	July, 2002			METHOD FOR TRIMERIZING ETHYLENE
JP2002233765	August, 2002			ETHYLENE TRIMERIZATION CATALYST AND ETHYLENE TRIMERIZATION METHOD USING THE SAME
JP3351068	November, 2002
JP2003071294	March, 2003			ETHYLENE TRIMERIZATION CATALYST AND METHOD FOR TRIMERIZING ETHYLENE BY USING THE CATALYST
JP3540827	July, 2004			PRODUCTION OF 1-HEXENE
JP3540828	July, 2004			PRODUCTION OF 1-HEXENE
JP3577786	October, 2004
MX200000017	December, 2000
NO167454	September, 1987
NO8701054	September, 1987
TW467921	December, 2001
WO/1997/037765	October, 1997			NOVEL CATALYST COMPOSITION
WO/1999/001460	January, 1999			CATALYST FOR THE PRODUCTION OF OLEFIN POLYMERS
WO/1999/019280	April, 1999			PROCESS FOR THE TRIMERIZATION OF OLEFINS
WO/2000/037175	June, 2000			CATALYST AND PROCESSES FOR OLEFIN TRIMERIZATION
WO/2000/050470	August, 2000			CATALYSTS CONTAINING N-PYRROLYL SUBSTITUTED NITROGEN DONORS
WO/2001/010876	February, 2001			POLYMERISATION PROCESS CATALYSED BY A BIDENTATE BISPHOSPHINE-GROUP VIII METAL COMPLEX
WO/2001/048028	July, 2001			OLEFIN PRODUCTION
WO/2001/047839	July, 2001			PROCESSES FOR PREVENTING GENERATION OF HYDROGEN HALIDES IN AN OLIGOMERIZATION PRODUCT RECOVERY SYSTEM
WO/2001/068572	September, 2001			PROCESS FOR THE PREPARATION OF 1-HEXENE
WO/2001/083447	November, 2001			A HALOPYRROLE LIGAND FOR USE IN A CATALYST SYSTEM
WO/2002/004119	January, 2002			OLEFIN TRIMERISATION USING A CATALYST COMPRISING A SOURCE OF CHROMIUM, MOLYBDENUM OR TUNGSTEN AND A LIGAND CONTAINING AT LEAST ONE PHOSPHOROUS, ARSENIC OR ANTIMONY ATOM BOUND TO AT LEAST ONE (HETERO)HYDROCARBYL GROUP
WO/2002/038628	May, 2002			SUBSTITUTED PYRIDYL AMINE LIGANDS, COMPLEXES AND CATALYSTS THEREFROM; PROCESSES FOR PRODUCING POLYOLEFINS THEREWITH
WO/2002/046249	June, 2002			METHODS OF COPOLYMERIZING ETHYLENE AND ISOBUTYLENE AND POLYMERS MADE THEREBY
WO/2002/066404	August, 2002			CATALYST SYSTEM FOR THE TRIMERISATION OF OLEFINS
WO/2002/066405	August, 2002			CATALYST SYSTEM FOR THE TRIMERISATION OF OLEFINS
WO/2002/083306	October, 2002			OLIGOMERISATION PROCESS AND CATALYST SYSTEM
WO/2003/004158	January, 2003			CATALYST COMPRISING CHROMIUM AND A LIGAND COMPRISING A SUBSTITUTED CYCLOPENTADIENE AND ITS USE FOR TRIMERISING OLEFINS
WO/2003/053890	July, 2003			TRIMERISATION AND OLIGOMERISATION OF OLEFINS USING A CHROMIUM BASED CATALYST
WO/2003/053891	July, 2003			TRIMERISATION AND OLIGOMERISATION OF OLEFINS USING A CHROMIUM BASED CATALYST
WO/2004/056477	July, 2004			TRIMERISATION OF OLEFINS
WO/2004/056478	July, 2004			TETRAMERIZATION OF OLEFINS
WO/2004/056479	July, 2004			TETRAMERIZATION OF OLEFINS
WO/2004/056480	July, 2004			TANDEM TETRAMERISATION-POLYMERISATION OF OLEFINS
WO/2004/083263	September, 2004			POLYMERISATION AND OLIGOMERISATION CATALYSTS
WO/2005/123633	December, 2005			OLIGOMERISATION OF OLEFINIC COMPOUNDS IN AN ALIPHATIC MEDIUM
WO/2005/123884	December, 2005			OLIGOMERISATION IN THE PRESENCE OF BOTH A TETRAMERISATION CATALYST AND A FURTHER OLIGOMERISATION CATALYST
WO/2006/096881	September, 2006			METHODS FOR OLIGOMERIZING OLEFINS
WO/2007/007272	January, 2007			OLIGOMERISATION OF OLEFINIC COMPOUNDS IN THE PRESENCE OF A DILUTED METAL CONTAINING ACTIVATOR
ZA8701859	April, 1988
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S. Naqvi, “1-Hexene From Ethylene By the Phillips Trimerization Technology,” available on-line at http://www.sriconsulting.com/PEP/Reports/Phase—95/RW95-1-1/RW95-1-8.html, Dec. 1997.

Lu, Caixia

PRIORITY CLAIM

This application claims the benefit of and priority to U.S. provisional application Ser. No. 60/660,018, filed Mar. 9, 2005.

The invention claimed is:

1. A composition comprising: (1) a ligand characterized by the following general formula: wherein R¹ and R²⁰ are each independently a ring having from 4-8 atoms in the ring, provided that R¹ or R²⁰ do not equal T-J, where T-J is as given by the general formula above and defined below; T is a bridging group of the general formula —(T′R²R³)—, where T′ is selected from the group consisting of carbon and silicon, R² and R³ are independently selected from the group consisting of hydrogen, halogen, and optionally substituted alkyl, heteroalkyl, aryl, heteroaryl, alkoxy, aryloxy, silyl, boryl, phosphino, amino, alkylthio, arylthio, and combinations thereof, provided that two or more R² and/or R³ groups may be joined together to form one or more optionally substituted ring systems having from 3-50 non-hydrogen atoms; J is an optionally substituted five-membered heterocycle, containing at least one nitrogen atom as part of the ring; (2) a metal precursor compound characterized by the general formula Cr(L)_n where each L is independently selected from the group consisting of halide, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, heteroalkyl, substituted heteroalkyl heterocycloalkyl, substituted heterocycloalkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, aryloxy, hydroxy, boryl, silyl, amino, amine, hydrido, allyl, diene, seleno, phosphino, phosphine, ether, thioether, carboxylates, thio, 1,3-dionates, oxalates, carbonates, nitrates, sulfates, ethers, thioethers and combinations thereof, wherein two or more L groups may be combined in a ring structure having from 3 to 50 non-hydrogen atoms; n is 1, 2, 3, 4, 5, or 6; and (3) optionally, one or more activators.

2. The composition of claim 1, wherein the ligand is characterized by the following general formula: wherein R¹, R²⁰, and T are described above; and X¹ is nitrogen or —C(R⁸)_n″—, X², X³, and X⁴ are selected from the group consisting of oxygen, sulfur, —C(R⁸)_n′—, —N(R⁸)_n″—, and provided that X¹ is —C(R⁸)_n″ or at least one of X², X³, or X⁴ is —C(R⁸)_n′ each n′ is 1 or 2 and each n″ is 0 or 1; and, each R⁸ is independently selected from the group consisting of hydrogen, halogen, nitro, and optionally substituted alkyl, heteroalkyl, aryl, heteroaryl, alkoxy, aryloxy, silyl, boryl, phosphino, amino, alkylthio, arylthio, and combinations thereof, and optionally two or more R¹, R²⁰, R², R³, and R⁸ groups may be joined to form one or more optionally substituted ring systems.

3. The composition of claim 2, wherein X⁴ is —C(R₈)_n″—, wherein n″=1, and R⁸ is optionally substituted phenyl.

4. The composition of claim 3, wherein R⁸ is phenyl.

5. The composition of claim 1, wherein R² and R³ are joined together to form one or more optionally substituted ring systems having from 3-50 non-hydrogen atoms.

FIELD OF THE INVENTION

This invention relates to the selective oligomerization (specifically trimerization and/or tetramerization) of olefins (specifically ethylene) using catalysts.

BACKGROUND OF THE INVENTION

The oligomerization of ethylene typically returns a broad distribution of 1-olefins having an even number of carbon atoms (C ₄ , C ₆ , C ₈ , C ₁₀ , etc.). These products range in commercial value, of which 1-hexene may be the most useful, as it is a comonomer commonly used in the production of commercial ethylene based copolymers.

Several catalysts useful for the oligomerization of olefin monomers have been developed, including the trimerization of ethylene. Several of these catalysts use chromium as a metal center. For example, U.S. Pat. No. 4,668,838, assigned to Union Carbide Chemicals and Plastics Technology Corporation, discloses a chromium catalyst complex formed by contacting a chromium compound with hydrolyzed hydrocarbyl aluminum and a donor ligand such as hydrocarbyl isonitriles, amines, and ethers. U.S. Pat. No. 5,137,994 discloses a chromium catalyst formed by the reaction products of bis-triarylsilyl chromates and trihydrocarbylaluminum compounds.

U.S. Pat. No. 5,198,563 and related patents, issued to Phillips Petroleum Company, disclose chromium-containing catalysts containing monodentate amide ligands. A chromium catalyst complex formed by contacting an aluminum alkyl or a halogenated aluminum alkyl and a pyrrole-containing compound prior to contacting with a chromium containing compound is disclosed in U.S. Pat. Nos. 5,382,738, 5,438,027, 5,523,507, 5,543,375, and 5,856,257. Similar catalyst complexes are also disclosed in EP0416304B1, EP0608447B1, EP0780353B1, and CA2087578.

Several patents assigned to Mitsubishi Chemicals also disclose chromium catalyst complexes formed from a chromium compound, a pyrrole ring-containing compound, an aluminum alkyl, and a halide containing compound, including U.S. Pat. Nos. 5,491,272, 5,750,817, and 6,133,495. Other catalyst complexes are formed by contacting a chromium compound with a nitrogen containing compound such as a primary or secondary amine, amide, or imide, and an aluminum alkyl, as disclosed in U.S. Pat. Nos. 5,750,816, 5,856,612, and 5,910,619.

EP0537609 discloses a chromium complex containing a coordinating polydentate ligand and an alumoxane. Similarly, CA2115639 discloses a polydentate phosphine ligand.

EP0614865B1, issued to Sumitomo Chemical Co., Ltd., discloses a catalyst prepared by dissolving a chromium compound, a heterocyclic compound having a pyrrole ring or an imidazole ring, and an aluminum compound. EP0699648B1 discloses a catalyst obtained by contacting chromium containing compound with a di- or tri-alkyl aluminum hydride, a pyrrole compound or a derivative thereof, and a group 13 (III B) halogen compound.

WO03/053890, and McGuinness et al., J. Am. Chem. Soc. 125, 5272-5273, (2003), disclose a chromium complex of tridentate phosphine ligands and methylalumoxane (MAO) cocatalyst. However, due to serious drawbacks in the preparation of the phosphine-containing system, the use of a thioether donor group to replace the phosphorus donor in the ligands was also investigated.

WO02/083306A2 discloses a catalyst formed from a chromium source, a substituted phenol, and an organoaluminum compound. WO03/004158A2 discloses a catalyst system which includes a chromium source and a ligand comprising a substituted five membered carbocyclic ring or similar derivatives.

U.S. Pat. No. 5,968,866 discloses a catalyst comprising a chromium complex which contains a coordinating asymmetric tridentate phosphane, arsane, or stibane ligand (hydrocarbyl groups) and an alumoxane. Carter et al., Chem. Commun., 2002, pp. 858-859 disclosed an ethylene trimerization catalyst obtained by contacting a chromium source, ligands bearing ortho-methoxy-substituted aryl groups, and an alkyl alumoxane activator. Similarly, WO02/04119A1 discloses a catalyst comprising a source of chromium, molybdenum, or tungsten, and a ligand containing at least one phosphorus, arsenic, or antimony atom bound to at least one (hetero)hydrocarbyl group.

Other pertinent references include J. Am. Chem. Soc. 123, 7423-7424 (2001), WO01/68572A1, WO02/066404A1, WO04/056477, WO04/056478, WO04/056479, WO04/056480, EP1110930A1, U.S. Pat. Nos. 3,333,016, 5,439,862, 5,744,677, and 6,344,594 and U.S. Pat. App. Pub. No. 2002/0035029A1. Japanese patent application JP 2001187345A2 (Tosoh Corp., Japan) discloses ethylene trimerization catalysts comprising chromium complexes having ligands which are amines substituted with two (pyrazol-1-yl)methyl groups.

Although each of the above described catalysts is useful for the trimerization of ethylene, there remains a desire to improve the performance of olefin oligomerization catalysts from the standpoint of productivity and selectivity for oligomers such as 1-hexene or 1-octene.

Several pyridyl amine catalyst complexes have been disclosed for the polymerization or copolymerization of ethylene, propylene, isobutylene, octene, and styrene by Symyx Technologies, Inc. in U.S. Pat. Nos. 6,713,577, 6,750,345, 6,706,829, 6,727,361, and 6,828,397. Pyridyl amines were also disclosed in U.S. Pat. Nos. 6,103,657 and 6,320,005, assigned to Union Carbide Chemical and Plastics Technology Corporation, in which zirconium was used as the metal center, and the catalyst complex was used to polymerize alpha-olefins, and in U.S. Pat. No. 5,637,660, assigned to Lyondell Petrochemical Company, which also describes Group 4 complexes of pyridyl amine ligands. Robertson et al., Inorg. Chem. 42, pp 6875-6885 (2003), discloses chromium complexes of tris(2-pyridylmethyl)amine for ethylene polymerization.

This invention also relates to U.S. Patent Application Ser. Nos. 60/611,943, 11/232,982 and 11/233,227.

What is needed is a catalyst system that can be readily prepared and that selectively oligomerizes ethylene or other olefins with both high activity and high selectivity.

SUMMARY OF THE INVENTION

The present invention provides methods and compositions to produce oligomers of olefins, comprising reacting olefins with a catalyst system under oligomerization conditions. The oligomerization reaction can have a selectivity of at least 70 mole percent for the desired oligomer. Typically the catalyst system is formed from the combination of:

• • 1) a ligand characterized by the following general formula:

• • where R ¹ and R ²⁰ can each be independently selected from the group consisting of hydrogen and optionally substituted hydrocarbyl, heteroatom containing hydrocarbyl and silyl, provided that R ¹ or R ²⁰ do not equal T-J, where T-J can be as given by the general formula above and defined below; T can be a bridging group of the general formula —(T′R ² R ³ )—, where T′ is selected from the group consisting of carbon and silicon, R ² and R ³ can each be independently selected from the group consisting of hydrogen, halogen, and optionally substituted alkyl, heteroalkyl, aryl, heteroaryl, alkoxy, aryloxy, silyl, boryl, phosphino, amino, alkylthio, arylthio, and combinations thereof, provided that two or more R ² and/or R ³ groups may be joined together to form one or more optionally substituted ring systems having from 3-50 non-hydrogen atoms; J can be an optionally substituted five-membered heterocycle, containing at least one nitrogen atom as part of the ring;
  • 2) a metal precursor compound characterized by the general formula Cr(L) _n where each L can be independently selected from the group consisting of halide, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, heteroalkyl, substituted heteroalkyl heterocycloalkyl, substituted heterocycloalkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, aryloxy, hydroxy, boryl, silyl, amino, amine, hydrido, allyl, diene, seleno, phosphino, phosphine, ether, thioether, carboxylates, thio, 1,3-dionates, oxalates, carbonates, nitrates, sulfates, ethers, thioethers and combinations thereof, wherein two or more L groups may be combined in a ring structure having from 3 to 50 non-hydrogen atoms; n is 1, 2, 3, 4, 5, or 6; and
  • 3) optionally, one or more activators.

In one embodiment, the ligand can be characterized by the following general formula:

where R ¹ , R ²⁰ , and T are described above; and X ¹ can be nitrogen or —C(R ⁸ ) _n″ —, X ² , X ³ , and X ⁴ can be selected from the group consisting of oxygen, sulfur, —C(R ⁸ ) _n′ —, —N(R ⁸ ) _n″ —, and provided that at least one of X ¹ , X ² , X ³ , or X ⁴ is carbon or —C(R ⁸ ) _n′ —; each n′ can be 1 or 2 and each n″ can be 0 or 1; and, each R ⁸ can be independently selected from the group consisting of hydrogen, halogen, nitro, and optionally substituted alkyl, heteroalkyl, aryl, heteroaryl, alkoxy, aryloxy, silyl, boryl, phosphino, amino, alkylthio, arylthio, and combinations thereof, and optionally two or more R ¹ , R ²⁰ , R ² , R ³ , and R ⁸ groups may be joined to form one or more optionally substituted ring systems.

In one embodiment, R ¹ and R ²⁰ can each be independently selected from hydrogen and optionally substituted alkyl, heteroalkyl, aryl, heteroaryl, silyl and combinations thereof.

In another embodiment, R ¹ is a hydrogen and R ²⁰ is an optionally substituted alkyl.

In another embodiment, R ¹ is not hydrogen when R ²⁰ is a cyclic group.

In still another embodiment, R ²⁰ is not a hydrogen when R ¹ is a cyclic group.

In another embodiment, R ¹ and R ²⁰ can each be independently a ring having from 4-8 atoms in the ring generally selected from the group consisting of substituted cycloalkyl, heterocycloalkyl, aryl, and heteroaryl.

The ligand used in varying embodiments of the present invention can be thiazole-amine ligand B1 as shown in FIG. 1.

The ligand used in varying embodiments of the present invention can be selected from the thiazole-amine ligands C1-C5 as shown in FIG. 2, especially ligands C1 and C5.

The ligand used in other embodiments of the present invention can be selected from the group consisting of the imidazole-amine ligands D1-D3 seen in FIG. 3, especially ligand D1.

A ligand used in another embodiment of the present invention can be oxadiazole ligand E1 as seen in FIG. 4.

The activator used in the method of the present invention can be selected from the group consisting of modified methylalumoxane (MMAO), methylalumoxane (MAO), trimethylaluminum (TMA), triisobutyl aluminum (TIBA), polymethylalumoxane-IP (PMAO), N,N-di(n-decyl)-4-n-butyl-anilinium tetrakis(perfluorophenyl)borate, and mixtures thereof.

The metal precursor used in the method of the present invention can be selected from the group consisting of (THF) ₃ CrMeCl ₂ , (THF) ₃ CrCl ₃ , (Mes) ₃ Cr(THF), [{TFA} ₂ Cr(OEt ₂ )] ₂ , (THF) ₃ CrPh ₃ , and mixtures thereof.

The method of the present invention can oligomerize, e.g. trimerize or tetramerize, C ₂ to C ₁₂ olefins. In one embodiment of the present invention, the olefin can be ethylene. The oligomerization or ethylene can produce 1-hexene, 1-octene, or mixtures thereof. The reaction in the method of the present invention can occur in a hydrocarbon solvent.

Further aspects of this invention will be evident to those of skill in the art upon review of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates heteroaryl-amine(thiazole-amine) ligand B1 according to an embodiment of the invention.

FIG. 2 illustrates heteroaryl-amine(thiazole-amine) ligands C1-C5 according to embodiments of the invention.

FIG. 3 illustrates heteroaryl-amine(imidazole-amine) ligands D1-D3 according to embodiments of the invention.

FIG. 4 illustrates heteroaryl-amine (oxadiazole-amine) ligand E1 according to an embodiment of the invention.

DETAILED DESCRIPTION

The inventions disclosed herein include chromium metal complexes and compositions, which are useful as catalysts for the selective oligomerization of olefins, specifically C2 to C12 olefins and especially C2 to C8 olefins, including the trimerization and/or tetramerization of ethylene.

For the purposes of this invention and the claims thereto when an oligomeric material (such as a dimer, trimer, or tetramer) is referred to as comprising an olefin, the olefin present in the material is the reacted form of the olefin. Likewise, the active species in a catalytic cycle may comprise the neutral or ionic forms of the catalyst. In addition, a reactor is any container(s) in which a chemical reaction occurs.

As used herein, the new numbering scheme for the Periodic Table Groups is used as set out in Chemical and Engineering News, 63(5), 27 (1985).

As used herein, the phrase “characterized by the formula” is not intended to be limiting and is used in the same way that “comprising” is commonly used. The term “independently selected” is used herein to indicate that the groups in question—e.g., R ¹ , R ² and R ³ — can be identical or different (e.g., R ¹ , R ² and R ³ may all be substituted alkyls, or R ¹ and R ² may be a substituted alkyl and R ³ may be an aryl, etc.). Use of the singular includes use of the plural and vice versa (e.g., a hexane solvent, includes hexanes). A named R group will generally have the structure that is recognized in the art as corresponding to R groups having that name. The terms “compound” and “complex” are generally used interchangeably in this specification, but those of skill in the art may recognize certain compounds as complexes and vice versa. In addition, the term “catalyst” will be understood by those of skill in the art to include either activated or unactivated forms of the molecules the comprise the catalyst, for example, a procatalyst and including complexes and activators or compositions of ligands, metal precursors and activators and optionally including scavengers and the like. For purposes of this invention, a catalyst system is defined to be the combination of an activator and a metal ligand complex or the combination of an activator, a ligand and a metal precursor. A metal ligand complex is defined to be the product of the combination of a metal precursor and a ligand. For the purposes of illustration, representative certain groups are defined herein. These definitions are intended to supplement and illustrate, not preclude, the definitions known to those of skill in the art.

“Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not. For example, the phrase “optionally substituted hydrocarbyl” means that a hydrocarbyl moiety may or may not be substituted and that the description includes both unsubstituted hydrocarbyl and hydrocarbyl where there is substitution.

The term “substituted” as in “substituted hydrocarbyl,” “substituted aryl,” “substituted alkyl,” and the like, means that in the group in question (i.e., the hydrocarbyl, alkyl, aryl or other moiety that follows the term), at least one hydrogen atom bound to a carbon atom is replaced with one or more substituent groups such as hydroxy, alkoxy, alkylthio, phosphino, amino, halo, silyl, and the like. When the term “substituted” introduces a list of possible substituted groups, it is intended that the term apply to every member of that group. That is, the phrase “substituted alkyl, alkenyl and alkynyl” is to be interpreted as “substituted alkyl, substituted alkenyl and substituted alkynyl.” Similarly, “optionally substituted alkyl, alkenyl and alkynyl” is to be interpreted as “optionally substituted alkyl, optionally substituted alkenyl and optionally substituted alkynyl.”

The term “saturated” refers to the lack of double and triple bonds between atoms of a radical group such as ethyl, cyclohexyl, pyrrolidinyl, and the like. The term “unsaturated” refers to the presence of one or more double and triple bonds between atoms of a radical group such as vinyl, allyl, acetylide, oxazolinyl, cyclohexenyl, acetyl and the like, and specifically includes alkenyl and alkynyl groups, as well as groups in which double bonds are delocalized, as in aryl and heteroaryl groups as defined below.

The terms “cyclo” and “cyclic” are used herein to refer to saturated or unsaturated radicals containing a single ring or multiple condensed rings. Suitable cyclic moieties include, for example, cyclopentyl, cyclohexyl, cyclooctenyl, bicyclooctyl, phenyl, napthyl, pyrrolyl, furyl, thiophenyl, imidazolyl, and the like. In particular embodiments, cyclic moieties include between 3 and 200 atoms other than hydrogen, between 3 and 50 atoms other than hydrogen or between 3 and 20 atoms other than hydrogen.

The term “hydrocarbyl” as used herein refers to hydrocarbyl radicals containing 1 to about 50 carbon atoms, specifically 1 to about 24 carbon atoms, most specifically 1 to about 16 carbon atoms, including branched or unbranched, cyclic or acyclic, saturated or unsaturated species, such as alkyl groups, alkenyl groups, aryl groups, and the like.

The term “alkyl” as used herein refers to a branched or unbranched saturated hydrocarbon group typically although not necessarily containing 1 to about 50 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, octyl, decyl, and the like, as well as cycloalkyl groups such as cyclopentyl, cyclohexyl and the like. Generally, although again not necessarily, alkyl groups herein may contain 1 to about 20 carbon atoms.

The term “alkenyl” as used herein refers to a branched or unbranched, cyclic or acyclic hydrocarbon group typically, although not necessarily, containing 2 to about 50 carbon atoms and at least one double bond, such as ethenyl, n-propenyl, isopropenyl, n-butenyl, isobutenyl, octenyl, decenyl, and the like. Generally, although again not necessarily, alkenyl groups herein contain 2 to about 20 carbon atoms.

The term “alkynyl” as used herein refers to a branched or unbranched, cyclic or acyclic hydrocarbon group typically although not necessarily containing 2 to about 50 carbon atoms and at least one triple bond, such as ethynyl, n-propynyl, isopropynyl, n-butynyl, isobutynyl, octynyl, decynyl, and the like. Generally, although again not necessarily, alkynyl groups herein may have 2 to about 20 carbon atoms.

The term “aromatic” is used in its usual sense, including unsaturation that is essentially delocalized across several bonds around a ring. The term “aryl” as used herein refers to a group containing an aromatic ring. Aryl groups herein include groups containing a single aromatic ring or multiple aromatic rings that are fused together, linked covalently, or linked to a common group such as a methylene or ethylene moiety. More specific aryl groups contain one aromatic ring or two or three fused or linked aromatic rings, e.g., phenyl, naphthyl, biphenyl, anthracenyl, or phenanthrenyl. In particular embodiments, aryl substituents include 1 to about 200 atoms other than hydrogen, typically 1 to about 50 atoms other than hydrogen, and specifically 1 to about 20 atoms other than hydrogen. In some embodiments herein, multi-ring moieties are substituents and in such embodiments the multi-ring moiety can be attached at an appropriate atom. For example, “naphthyl” can be 1-naphthyl or 2-naphthyl; “anthracenyl” can be 1-anthracenyl, 2-anthracenyl or 9-anthracenyl; and “phenanthrenyl” can be 1-phenanthrenyl, 2-phenanthrenyl, 3-phenanthrenyl, 4-phenanthrenyl, or 9-phenanthrenyl.

The term “alkoxy” as used herein intends an alkyl group bound through a single, terminal ether linkage; that is, an “alkoxy” group may be represented as —O-alkyl where alkyl is as defined above. The term “aryloxy” is used in a similar fashion, and may be represented as —O-aryl, with aryl as defined below. The term “hydroxy” refers to —OH.

Similarly, the term “alkylthio” as used herein intends an alkyl group bound through a single, terminal thioether linkage; that is, an “alkylthio” group may be represented as —S-alkyl where alkyl is as defined above. The term “arylthio” is used similarly, and may be represented as —S-aryl, with aryl as defined below. The term “mercapto” refers to —SH.

The terms “halo” and “halogen” are used in the conventional sense to refer to a chloro, bromo, fluoro or iodo radical.

The terms “heterocycle” and “heterocyclic” refer to a cyclic radical, including ring-fused systems, including heteroaryl groups as defined below, in which one or more carbon atoms in a ring is replaced with a heteroatom—that is, an atom other than carbon, such as nitrogen, oxygen, sulfur, phosphorus, boron or silicon. Heterocycles and heterocyclic groups include saturated and unsaturated moieties, including heteroaryl groups as defined below. Specific examples of heterocycles include pyridine, pyrrolidine, pyrroline, furan, tetrahydrofuran, thiophene, imidazole, oxazole, thiazole, indole, and the like, including any isomers of these. Additional heterocycles are described, for example, in Alan R. Katritzky, Handbook of Heterocyclic Chemistry , Pergammon Press, 1985, and in Comprehensive Heterocyclic Chemistry , A. R. Katritzky et al., eds., Elsevier, 2d. ed., 1996. The term “metallocycle” refers to a heterocycle in which one or more of the heteroatoms in the ring or rings is a metal.

The term “heteroaryl” refers to an aryl radical that includes one or more heteroatoms in the aromatic ring. Specific heteroaryl groups include groups containing heteroaromatic rings such as thiophene, pyridine, pyrazine, isoxazole, pyrazole, pyrrole, furan, thiazole, oxazole, imidazole, isothiazole, oxadiazole, triazole, and benzo-fused analogues of these rings, such as indole, carbazole, benzofuran, benzothiophene and the like.

More generally, the modifiers “hetero” and “heteroatom-containing”, as in “heteroalkyl” or “heteroatom-containing hydrocarbyl group” refer to a molecule or molecular fragment in which one or more carbon atoms is replaced with a heteroatom. Thus, for example, the term “heteroalkyl” refers to an alkyl substituent that is heteroatom-containing. When the term “heteroatom-containing” introduces a list of possible heteroatom-containing groups, it is intended that the term apply to every member of that group. That is, the phrase “heteroatom-containing alkyl, alkenyl and alkynyl” is to be interpreted as “heteroatom-containing alkyl, heteroatom-containing alkenyl and heteroatom-containing alkynyl.”

By “divalent” as in “divalent hydrocarbyl”, “divalent alkyl”, “divalent aryl” and the like, is meant that the hydrocarbyl, alkyl, aryl or other moiety is bonded at two points to atoms, molecules or moieties with the two bonding points being covalent bonds.

As used herein the term “silyl” refers to the —SiZ ¹ Z ² Z ³ radical, where each of Z ¹ , Z ² , and Z ³ is independently selected from the group consisting of hydrogen and optionally substituted alkyl, alkenyl, alkynyl, heteroatom-containing alkyl, heteroatom-containing alkenyl, heteroatom-containing alkynyl, aryl, heteroaryl, alkoxy, aryloxy, amino, silyl and combinations thereof.

As used herein the term “boryl” refers to the —BZ ¹ Z ² group, where each of Z ¹ and Z ² is as defined above. As used herein, the term “phosphino” refers to the group —PZ ¹ Z ² , where each of Z ¹ and Z ² is as defined above. As used herein, the term “phosphine” refers to the group :PZ ¹ Z ² Z ³ , where each of Z ¹ , Z ³ and Z ² is as defined above. The term “amino” is used herein to refer to the group —NZ ¹ Z ² , where each of Z ¹ and Z ² is as defined above. The term “amine” is used herein to refer to the group :NZ ¹ Z ² Z ³ , where each of Z ¹ , Z ² and Z ³ is as defined above.

In this specification, the metal-ligand complexes are sometimes referred to as, for example, (2,1) complexes or (3,1) complexes, with the first number representing the number of coordinating atoms and second number representing the number of anionic sites on the heterocycle-amine ligand, when the metal-ligand bonding is considered from an ionic bonding model perspective, with the metal considered to be cationic and the ligand considered to be anionic. From a covalent bonding model perspective, a (2,1) complex may be considered to be a complex in which the heterocycle-amine ligand is bound to the metal center via one covalent bond and one dative bond, while a (3,1) complex may be considered to be a complex in which the heterocycle-amine ligand is bound to the metal center via one covalent bond and two dative bonds.

Throughout the Figures and the following text, several abbreviations may be used to refer to specific compounds or elements. Abbreviations for atoms are as given in the periodic table (Li=lithium, for example). Other abbreviations that may be used are as follows: “i-Pr” to refer to isopropyl; “t-Bu” to refer to tertiary-butyl; “i-Bu” to refer to isobutyl; “Me” to refer to methyl; “Et” to refer to ethyl; “Ph” to refer to phenyl; “Mes” to refer to mesityl (2,4,6-trimethyl phenyl); “TFA” to refer to trifluoroacetate; “THF” to refer to tetrahydrofuran; “TsOH” to refer to para-toluenesulfonic acid; “cat.” to refer to catalytic amount of; “LDA” to refer to lithium diisopropylamide; “DMF” to refer to dimethylformamide; “eq.” to refer to molar equivalents; “TMA” to refer to AlMe ₃ ; “TIBA” to refer to Al i-(Bu) ₃ . SJ ₂ BF ₂₀ refers to [(n-C ₁₀ H ₂₁ ) ₂ (4-n-C ₄ H ₉ —C ₆ H ₄ )NH][B(C ₆ F ₅ ) ₄ ].

This invention relates to methods for selectively oligomerizing (e.g., trimerizing and/or tetramerizing) C ₂ to C ₁₂ olefins, specifically ethylene, comprising reacting a catalytic composition or compound(s), optionally with one or more activators, with the olefin. As referred to herein, selective oligomerization refers to producing the desired oligomer with a selectivity of the reaction being at least 70%, more specifically at least 80% by mole of oligomer, with the possibility that an acceptable amount of polymer is present, but with the preference that no polymer is present in the product. In other embodiments, less than 20 weight % of polymer is present, specifically less than 5 weight %, more specifically less than 2 weight %, based upon the total weight of monomer converted to oligomers and polymers, where a polymer is defined to mean a molecule comprising more than 100 mers. In other embodiments, selective oligomerization refers to producing two desired oligomers, with the selectivity of the two desired oligomers summing to at least 80% by sum of mole of oligomers.

In another embodiment, this invention relates to a method to trimerize or tetramerize a C ₂ to C ₁₂ olefin wherein the method produces at least 70% selectivity for the desired oligomer(s) (specifically at least 80%, specifically at least 85%, specifically at least 90%, specifically at least 95%, specifically at least 98%, specifically at least 99%, specifically 100%), calculated based upon the amount of the desired oligomer produced relative to the total yield; and at least 70% of the olefin monomer reacts to form product (specifically at least 80%, specifically at least 85%, specifically at least 90%, specifically at least 95%, specifically at least 98%, specifically at least 99%, specifically 100%).

This invention may also relate to novel metal ligand complexes and or novel combinations of specific ligands disclosed herein and metal precursors.

The methods of this invention specifically contact the desired monomers with a metal ligand complex or a combination of a ligand and a metal precursor (and optional activators) to form the desired oligomer. Preferred ligands useful in the present invention may be characterized by the general formula:

• • where R ¹ and R ²⁰ are each independently selected from the group consisting of hydrogen and optionally substituted hydrocarbyl, heteroatom containing hydrocarbyl and silyl. In some embodiments, R ¹ and R ²⁰ are each independently selected from hydrogen and optionally substituted alkyl, heteroalkyl, aryl, heteroaryl, silyl and combinations thereof. In certain embodiments, R ¹ and R ²⁰ are each independently a ring having from 4-8 atoms in the ring selected from the group consisting of substituted cycloalkyl, heterocycloalkyl, aryl and heteroaryl, provided that R ¹ and R ²⁰ do not equal T-J, where T-J is as shown in Formula (I) above and defined below.

T is a bridging group characterized by the general formula —(T′R ² R ³ )—, where each T′ is independently selected from the group consisting of carbon and silicon, R ² and R ³ are independently selected from the group consisting of hydrogen, halogen, and optionally substituted alkyl, heteroalkyl, aryl, heteroaryl, alkoxy, aryloxy, silyl, boryl, phosphino, amino, alkylthio, arylthio, and combinations thereof, provided that two or more R ² and/or R ³ groups may be joined together to form one or more optionally substituted ring systems, such as saturated, unsaturated or aromatic ring systems having from 3-50 non-hydrogen atoms (e.g., cyclopropyl, where T′=C, and R ² and R ³ together form —CH ₂ —CH ₂ —; or cyclohexyl, where T′=C and the two R ² groups together form —CH ₂ —CH ₂ —CH ₂ —CH ₂ —).

J is an optionally substituted five-membered heterocycle, containing at least one nitrogen atom as part of the ring. In some embodiments, J is specifically a five-membered heteroaryl containing at least one nitrogen atom as part of the ring.

In more specific embodiments, R ¹ and R ²⁰ are each independently selected from the group consisting of hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl and combinations thereof. Even more specifically, R ²⁰ is hydrogen and R ¹ is selected from the group consisting of alkyl, substituted alkyl, aryl, and substituted aryl.

In some other embodiments, R ² is hydrogen, and R ³ is selected from the group consisting of aryl, substituted aryl, heteroaryl, substituted heteroaryl, primary and secondary alkyl groups, and —PY ₂ where Y is selected from the group consisting of aryl, substituted aryl, heteroaryl, and substituted heteroaryl.

In particular embodiments, when J is a five-membered heterocycle, the heterocycle contains at least two but no more than four heteroatoms. In more particular embodiments, at least one of the heteroatoms is a nitrogen, oxygen, or sulfur in a ring position adjacent to the ring atom that is bonded to T.

In one embodiment, the heterocycle-amine ligands can be characterized as ligands where J is a five-membered heterocycle or substituted heterocycle group. These ligands may be characterized by the general formula:

• • where R ¹ , R ²⁰ , and T are as described above.

In Structure (III) (and throughout this specification), the presence of one solid line and one dashed line between any pair of atoms is intended to indicate that the bond in question may be a single bond or a double bond, or a bond with bond order intermediate between single and double, such as the delocalized bonding in an aromatic ring. In some embodiments of the structure of formula III, X ¹ is nitrogen or —C(R ⁸ ) _n″ —, X ² , X ³ , and X ⁴ are selected from the group consisting of oxygen, sulfur, —C(R ⁸ ) _n′ —, —N(R ⁸ ) _n″ —, and provided that X ¹ is —C(R ⁸ ) _n″ or at least one of X ² , X ³ , or X ⁴ is —C(R ⁸ ) _n′ — (within the above definitions), each n′ is 1 or 2 and each n″ is 0 or 1 (depending, e.g., on the degree of saturation of the ring). Each R ⁸ is independently selected from the group consisting of hydrogen, halogen, nitro, and optionally substituted alkyl, heteroalkyl, aryl, heteroaryl, alkoxy, aryloxy, silyl, boryl, phosphino, amino, alkylthio, arylthio, and combinations thereof, and optionally two or more R ¹ , R ²⁰ , R ² , R ³ , and R ⁸ groups may be joined to form one or more optionally substituted ring systems. In more specific embodiments, the heterocycle ring in formula III is an optionally substituted heteroaryl ring, where n′ is 1 and n″ is 0 or 1, and provided that when X ¹ is —C(R ⁸ ) _n″ —, n″ is 0.

In certain more specific embodiments, X ⁴ is selected from the group consisting of —C(R ⁹ )— wherein R ⁹ is specifically selected from the group consisting of optionally substituted aryl and heteroaryl.

The detailed synthesis of certain types of heterocycle-amine ligands are specifically discussed below, including thiazole-amine ligands, imidazole-amine ligands, and oxadiazole-amine ligands. Those of ordinary skill in the art will be able to synthesize other embodiments.

Thiazole-amine ligands can be prepared according to the general reaction scheme outlined in Scheme 2, in which a substituted thiazole-amine aldehyde is prepared from the corresponding bromo-aldehyde in a coupling reaction. The resultant substituted thiazole-amine aldehyde is then reacted with a primary amine to form the intermediate imine, which is then reacted with a nucleophile to provide the corresponding amine.

• • where R ⁸ , X ³ , X ² , R ¹ , R ² and M are as defined above. R can be any suitable hydrocarbyl.

Generally, R ² M is a nucleophile such as an alkylating, arylating or hydrogenating reagent and M is a metal such as a main group metal, or a metalloid such as boron. The alkylating, arylating or hydrogenating reagent may be a Grignard, alkyl or aryl-lithium or borohydride reagent. In step 4, a complexing agent such as magnesium bromide can be used to direct the nucleophile selectively to the imine carbon, as described in U.S. Pat. Nos. 6,750,345 and 6,713,577. R ³ can be installed (into the bridging group T, and as defined above in relation to Formula (I) above) through nucleophilic addition to the appropriate ketimine, which can be obtained through a variety of known synthetic procedures.

In the reaction scheme shown in Scheme 2, from formula (III), X ¹ is shown as carbon and X ⁴ is shown as CR ⁸ . R ³ can be installed (into the bridging group T, and as defined above in relation to Formula (I) above) through nucleophilic addition to the appropriate ketimine, which can be obtained through a variety of known synthetic procedures. Using this approach, it is possible in many embodiments to introduce a wide variety of diverse substituents in the ligands of the invention, which can be significant in the design of libraries or arrays for high throughput or combinatorial methods.

For ligands where the appropriate bromo-thiazole aldehyde is not commercially available, a variety of alternative synthetic techniques can be used. In some such embodiments, the aldehyde can be prepared from commercially available precursors, with the group in the R ⁸ position being installed either before or after the introduction of the aldehyde substituent, depending on the particular chemistry.

Thus, for example, commercially available di-bromo thiazole AA(1) can be used as the starting point in the preparation of a variety of thiazole-amine (i.e., (thiazol-2-yl)-alkyl amine) ligands, such as ligand B1, as illustrated in FIG. 1, yielding bromo-aldehyde AA(2) upon regioselective lithium-halide exchange, followed by DMF addition as shown in Scheme 3. AA(2) can then be further functionalized according to the reaction scheme illustrated in Scheme 2, as discussed above.

Similarly, AA(1) can also be used to prepare (thiazol-4-yl)-alkyl amine ligands (e.g., ligands selected from C1-C5, as illustrated in FIG. 2) as shown by the reaction scheme illustrated in Scheme 4. The bromo group first replaced in Scheme 4 is believed to be more reactive and undergoes lithium-halide exchange first. Subsequent R ⁸ addition (e.g. through Suzuki coupling) gives BB(1). Aldehyde BB(2) can then be generated by a second lithium-halide exchange followed by addition of DMF.

• • where R ⁸ is as defined above.

In the case of imidazole-containing ligands (e.g., imidazole-amines refer to ((imidazol-2-yl)-alkyl amines) and ((imidazol-4-yl)-alkyl amines)), the imidazole ring can be prepared using known techniques, as described, for example, in Heterocycles 39, pp 139-153 (1994) and illustrated in Scheme 5.

where R ¹ , R ² and R ⁸ are as defined above, and R ³ can be installed (into the bridging group T, and as defined above in relation to Formula (I) above) through nucleophilic addition to the appropriate ketimine, which can be obtained through a variety of known synthetic procedures. A number of approaches can be used for installation of the various possible R ⁸ substituents, as illustrated by the Schemes 6-9 below. One approach begins with commercially available tribromoimidazole CC(2) or CC(1), as shown in Scheme 6. Two of the three bromine substituents in CC(2) can be removed in a regioselective manner because of the difference in reactivities, and the resulting bromo-imidazole CC(4) can then be further functionalized by treatment with LDA, followed by DMF addition to give desired aldehyde CC(5). Where the appropriate tribromoimidazole CC(2) is not commercially available, it can be obtained through R ⁸ substitution of tribromoimidazole CC(1). In many cases, bromo-imidazole CC(4) can also be accessed directly through substitution of 4-bromo-imidazole, which is commercially-available.

• • where R ⁸ is as defined above.

Aldehyde CC(5) can also be generated in a one-pot reaction from the tribromo-imidazole CC(2), as shown in Scheme 7, where the tribromo-imidazole is first treated with 2 equivalents of n-BuLi, followed by addition of 1 equivalent of acid and subsequent treatment with DMF.

where R ⁸ is as defined above.

Dibromoimidazole CC(3) can be used as an access point for functionalization at the R ⁸ position shown specifically in Scheme 8. The difference in reactivity of the two bromo substituents makes it possible to install different R groups at the various R ⁸ positions regioselectively, via sequential Suzuki coupling reactions using different boronic acids to give the aldehyde CC(8), as shown in Scheme 8.

where each R ⁸ is, independently, as defined above.

Aldehyde CC(8) may also be prepared by first installing the aldehyde (to give CC(9)), followed by sequential Suzuki coupling reactions, as shown in Scheme 9.

where each R ⁸ is, independently, as defined above.

Additionally, for thiazole-amine and imidazole-amine ligands, when R ²⁰ is not hydrogen, the R ²⁰ group may be installed through condensation of the aldehyde with a secondary amine, through nucleophilic addition of R ²⁰ M to the imine nitrogen, or through a variety of other known synthetic procedures.

Oxadiazole amine ligands can be synthesized by the cycloaddition of hydroximinoyl chlorides with nitriles as depicted in Scheme 10, below. GG(1) is converted, in situ, to the nitrile oxide dipole I(1) in the presence of base (Liu, et al., J. Org. Chem. 45, pp 3916-3918 (1980), which then undergoes a 3+2 cycloaddition with GG(2) (see Torssell, Nitrile Oxides, Nitrones, and Nitronates in Organic Synthesis; VCH: New York, 1988, pp. 55-74 and Jager, et al., “Nitrile Oxides,” in Synthetic Applications of 1,3-Dipolar Cycloaddition Chemistry Toward Heterocycles and Natural Products; Padwa, et al., Eds.; Wiley: Chichester, 2002). I(1) can also be formed by other methods; see Carriera, et al., Org. Lett. 2, pp 539-541 (2000), and Sibi, et al., J. Am. Chem. Soc. 126, pp 5366-5367 (2004). Some examples of hydroximinoyl chlorides GG(1) are commercially available or can be prepared using known procedures (see, for example, the references cited above). Examples of GG(2), when R ² and R ³ ═H, or when R ² =aryl and R ³ ═H, can be prepared according to known procedures (Jones, et al., J. Med. Chem. 28, pp 1468-1476 (1985); McEwen, et al., J. Org. Chem. 45, pp 1301-1308 (1980)). Alternatively GG(2) might be synthesized by cyanation of imines (see Naim, et al., Indian J. Chem. 19B, pp 622-624 (1980); Kobayashi, et al., J. Am. Chem. Soc. 119, pp 10049-10053 (1997)).

where R ¹ , R ² , R ³ , and R ⁸ are as defined above.

Alternative strategies to the reaction schemes illustrated in Schemes 2-10 can also be employed.

Once the desired ligand is formed, it can be combined with a Cr atom, ion, compound or other Cr precursor compound, and in some embodiments the present invention encompasses compositions that include any of the above-mentioned ligands in combination with an appropriate Cr precursor and an optional activator. For example, in some embodiments, the Cr precursor can be an activated Cr precursor, which refers to a Cr precursor (described below) that has been combined or reacted with an activator (described below) prior to combination or reaction with the ancillary ligand. As noted above, in one aspect the invention provides compositions that include such combinations of ligand and Cr atom, ion, compound or precursor. In some applications, the ligands are combined with a Cr compound or precursor and the product of such combination is not determined, if a product forms. For example, the ligand may be added to a reaction vessel at the same time as the Cr precursor compound along with the reactants, activators, scavengers, etc. Additionally, the ligand can be modified prior to addition to or after the addition of the Cr precursor, e.g., through a deprotonation reaction or some other modification.

The Cr metal precursor compounds may be characterized by the general formula Cr(L) _n where L is an organic group, an inorganic group, or an anionic atom; and n is an integer of 1 to 6, and when n is not less than 2, L may be the same or different from each other. Each L is a ligand independently selected from the group consisting of hydrogen, halogen, optionally substituted alkyl, heteroalkyl, allyl, diene, alkenyl, heteroalkenyl, alkynyl, heteroalkynyl, aryl, heteroaryl, alkoxy, aryloxy, boryl, silyl, amino, phosphino, ether, thioether, phosphine, amine, carboxylate, alkylthio, arylthio, 1,3-dionate, oxalate, carbonate, nitrate, sulfate, and combinations thereof. Optionally, two or more L groups are joined into a ring structure. One or more of the ligands L may be ionically bonded to Cr and, for example, L may be a non-coordinated or loosely coordinated or weakly coordinated anion (e.g., L may be selected from the group consisting of those anions described below in the conjunction with the activators). See Marks et al., Chem. Rev. 100, pp 1391-1434 (2000) for a detailed discussion of these weak interactions. The chromium precursors may be monomeric, dimeric or higher orders thereof.

Specific examples of suitable chromium precursors include, but are not limited to (THF) ₃ CrMeCl ₂ , (Mes) ₃ Cr(THF), [{TFA} ₂ Cr(OEt ₂ )] ₂ , (THF) ₃ CrPh ₃ , CrCl ₃ (THF) ₃ , CrCl ₄ (NH ₃ ) ₂ , Cr(NMe ₃ ) ₂ Cl ₃ , CrCl ₃ , Cr(acac) ₃ (acac=acetylacetonato), Cr(2-ethylhexanoate) ₃ , Cr(neopentyl) ₄ , Cr(CH ₂ -C ₆ H ₄ -o-NMe ₂ ) ₃ , Cr(TFA) ₃ , Cr(CH(SiMe ₃ ) ₂ ) ₃ , Cr(Mes) ₂ (THF) ₃ , Cr(Mes) ₂ (THF), Cr(Mes)Cl(THF) ₂ , Cr(Mes)Cl(THF) _0.5 , Cr(p-tolyl)Cl ₂ (THF) ₃ , Cr(diisopropylamide) ₃ , Cr(picolinate) ₃ , [Cr ₂ Me ₈ ][Li(THF)] ₄ , CrCl ₂ (THF), Cr(NO ₃ ) ₃ , [CrMe ₆ ][Li(Et ₂ O)] ₃ [CrPh ₆ ][Li(THF)] ₃ , [CrPh6][Li(n-Bu ₂ O)] ₃ , [Cr(C ₄ H ₈ ) ₃ ][Li(THF)] ₃ , and other well known chromium compounds commonly used as precursors in the formation of Cr complexes and catalysts.

The ligand may be mixed with a suitable metal precursor compound prior to or simultaneously with allowing the mixture to be contacted with the reactants (e.g., monomers). In this context, the ligand to metal precursor compound ratio can be in the range of about 0.01:1 to about 100:1, more specifically in the range of about 0.1:1 to about 10:1.

Generally, the ligand (or optionally a modified ligand as discussed above) is mixed with a suitable Cr precursor (and optionally other components, such as an activator, or a reagent to exchange L groups on the chromium after contact between the chromium precursor and the ligand; e.g., Li(acac)) prior to or simultaneously with allowing the mixture to be contacted with the reactants (e.g., monomers). When the ligand is mixed with the Cr precursor compound, a Cr-ligand complex may be formed, which may itself be an active catalyst or may be transformed into a catalyst upon activation. In some embodiments the Cr precursor is contacted with other ligands, then activators, then monomers.

Cr-ligand complexes can take a number of different coordination modes. General examples of possible coordination modes include those characterized by the following general formulas:

wherein R ¹ , R ²⁰ , L, J and T are described above; x is 1 or 2; and m′ is 1, 2, 3, 4, or 5. J′ is defined the same as J is defined above, provided that J′ includes 2 atoms bonded to the Cr, one of the which is in the ring position adjacent to the atom bonded to T, which is bonded to Cr through a dative bond, and the other of which is bonded to the Cr through a covalent bond. The more specific embodiments of the ligands (e.g., formulas I and III) may replace the coordinated ligands drawn in formulae VI. Numerous other coordination modes are possible, for example the ligands may bind to two chromium metal centers in a bridging fashion (see for example Cotton and Walton, Multiple Bonds Between Metal Atoms 1993, Oxford University Press). Some studies (for example, Rensburg et al., Organometallics 23, pp 1207-1222 (2004)) suggest that the ligand environment around Cr may be different at different points in the catalytic cycle. Hemilabile ligands, which can change their binding mode to the metal, may be useful in this regard.

In some embodiments, the ligand will be mixed with a suitable metal precursor prior to or simultaneous with allowing the mixture to be contacted to the reactants. When the ligand is mixed with the metal precursor, a metal-ligand complex may be formed. In connection with the metal-ligand complex and depending on the ligand or ligands chosen, the metal-ligand complex may take the form of dimers, trimers or higher orders thereof or there may be two or more metal atoms that are bridged by one or more ligands. Furthermore, two or more ligands may coordinate with a single metal atom. The exact nature of the metal-ligand complex(es) formed depends on the chemistry of the ligand and the method of combining the metal precursor and ligand, such that a distribution of metal-ligand complexes may form with the number of ligands bound to the metal being greater than, equal to or less than the number of equivalents of ligands added relative to an equivalent of metal precursor.

Listed below are some examples of Cr-Ligand complex embodiments

• • wherein R ¹ , R ² , R ³ , R8, R ²⁰ , X ¹ , X ² , X ³ , X ⁴ , n′, n″, L, m′ and T are as defined above;
  • R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ and R ¹⁶ , if present, are independently selected from the group consisting of hydrogen, halogen, nitro, and optionally substituted alkyl, heteroalkyl, aryl, heteroaryl, alkoxy, aryloxy, silyl, boryl, phosphino, amino, alkylthio, arylthio, and combinations thereof, and optionally two or more R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ and R ¹⁶ groups may be joined to form one or more optionally substituted ring systems;
  • R ^u , R ^v , R ^w , R ^x , R ^y and R ^z are optionally substituted alkyl, heteroalkyl, aryl, heteroaryl;
  • E, if present, is a carbon atom that is part of an optionally substituted aryl or heteroaryl ring;
  • D, if present, is a ring selected from the group consisting of optionally substituted aryl and heteroaryl;
  • a dashed arrow indicates that the dative bond is an optional bond which may or may not be present;
  • LB is a Lewis base;
  • k=0 or 1.

In certain embodiments, where “E” is present, the aryl or heteroaryl ring may be polycyclic.

In addition, the catalyst systems of this invention may be combined with other catalysts in a single reactor and/or employed in a series of reactors (parallel or serial).

The ligands-metal-precursors combinations and the metal ligand complexes, described above, are optionally activated in various ways to yield compositions active for selective ethylene oligomerization. For the purposes of this patent specification and appended claims, the terms “cocatalyst” and “activator” are used herein interchangeably and are defined to be any compound which can activate any one of the ligands-metal-precursor-combinations and the metal ligand complexes, described above by converting the combination, complex, or composition into a catalytically active species. Non-limiting activators, for example, include alumoxanes, aluminum alkyls, other metal or main group alkyl or aryl compounds, ionizing activators, which may be neutral or ionic, Lewis acids, reducing agents, oxidizing agents, and combinations thereof.

In one embodiment, alumoxane activators are utilized as an activator in the compositions useful in the invention. Alumoxanes are generally oligomeric compounds containing —Al(R*)—O— sub-units, where R* is an alkyl group. Examples of alumoxanes include methylalumoxane (MAO), ethylalumoxane, isobutylalumoxane, and modified methylalumoxanes (MMAO), which include alkyl groups other than methyl such as ethyl, isobutyl, and n-octyl, such as MMAO-3A, PMAO-IP (referring to polymethylalumoxane, improved process, manufactured by Akzo-Nobel and meaning an MAO prepared from a non-hydrolytic process). Alkylalumoxanes and modified alkylalumoxanes are suitable as catalyst activators, particularly when the abstractable ligand of the catalyst is a halide, alkoxide or amide. Mixtures of different alumoxanes and modified alumoxanes may also be used.

The activator compounds comprising Lewis-acid activators and in particular alumoxanes are specifically characterized by the following general formulae
(R ^a —Al—O) _p
R ^b (R ^c —Al—O) _p —AlR ^e ₂

where R ^a , R ^b , R ^c and R ^e are, independently a C ₁ -C ₃₀ alkyl radical, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, and “p” is an integer from 1 to about 50. Most specifically, R ^a , R ^b , R ^c and R ^d are each methyl and “p” is a least 4. When an alkyl aluminum halide or alkoxide is employed in the preparation of the alumoxane, one or more R ^a , R ^b , R ^c or R ^e are groups may be halide or alkoxide.

It is recognized that alumoxane is not a discrete material. An alumoxane is generally a mixture of both the linear and cyclic compounds. A typical alumoxane will contain free trisubstituted or trialkyl aluminum, bound trisubstituted or trialkyl aluminum, and alumoxane molecules of varying degree of oligomerization. Those methylalumoxanes most preferred contain lower levels of trimethylaluminum. Lower levels of trimethylaluminum can be achieved by reaction of the trimethylaluminum with a Lewis base or by vacuum distillation of the trimethylaluminum or by any other means known in the art.

For further descriptions, see U.S. Pat. Nos. 4,665,208, 4,952,540, 5,041,584, 5,091,352, 5,206,199, 5,204,419, 4,874,734, 4,924,018, 4,908,463, 4,968,827, 5,329,032, 5,248,801, 5,235,081, 5,157,137, 5,103,031 and EP0561476A1, EP0279586B1, EP0516476A1, EP0594218A1 and WO94/10180.

When the activator is an alumoxane (modified or unmodified), some embodiments select the maximum amount of activator at a 5000-fold molar excess Al/Cr over the catalyst precursor. The minimum preferred activator-to-catalyst-precursor is a 1:1 molar ratio. More specifically, the Al/Cr ratio is from 1000:1 to 100:1.

Alumoxanes may be produced by the hydrolysis of the respective trialkylaluminum compound. MMAO may be produced by the hydrolysis of trimethylaluminum and a higher trialkylaluminum such as triisobutylaluminum. MMAO's are generally more soluble in aliphatic solvents and more stable during storage. There are a variety of methods for preparing alumoxane and modified alumoxanes, non-limiting examples of which are described in U.S. Pat. Nos. 4,665,208, 4,952,540, 5,091,352, 5,206,199, 5,204,419, 4,874,734, 4,924,018, 4,908,463, 4,968,827, 5,308,815, 5,329,032, 5,248,801, 5,235,081, 5,157,137, 5,103,031, 5,391,793, 5,391,529, 5,693,838, 5,731,253, 5,731,451, 5,744,656, 5,847,177, 5,854,166, 5,856,256 and 5,939,346 and European publications EP0561476A1, EP0279586B1, EP0594218A1 and EP0586665B1, and PCT publications WO94/10180 and WO99/15534, all of which are herein fully incorporated by reference. It may be preferable to use a visually clear methylalumoxane. A cloudy or gelled alumoxane can be filtered to produce a clear solution or clear alumoxane can be decanted from the cloudy solution. Another alumoxane is a modified methyl alumoxane (MMAO) cocatalyst type 3A (commercially available from Akzo Chemicals, Inc. under the trade name Modified Methylalumoxane type 3A, covered under patent number U.S. Pat. No. 5,041,584).

Aluminum alkyl or organoaluminum compounds which may be utilized as activators (or scavengers) include trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diisobutylaluminum hydride, ethylaluminum dichloride, diethylaluminum chloride, diethylaluminum ethoxide and the like.

Ionizing Activators

In some embodiments, the activator includes compounds that may abstract a ligand making the metal complex cationic and providing a charge-balancing non-coordinating or weakly coordinating anion. The term “non-coordinating anion” (NCA) means an anion which either does not coordinate to said cation or which is only weakly coordinated to said cation thereby remaining sufficiently labile to be displaced by a neutral Lewis base.

It is within the scope of this invention to use an ionizing or stoichiometric activator, neutral or ionic, such as tri(n-butyl)ammonium tetrakis(pentafluorophenyl)boron, a tris(perfluorophenyl)boron metalloid precursor or a tris(perfluoronaphthyl)boron metalloid precursor, polyhalogenated heteroborane anions (WO98/43983), boric acid (U.S. Pat. No. 5,942,459) or combination thereof. It is also within the scope of this invention to use neutral or ionic activators alone or in combination with alumoxane or modified alumoxane activators.

Examples of neutral stoichiometric activators include tri-substituted boron, tellurium, aluminum, gallium and indium or mixtures thereof. The three substituent groups are each independently selected from alkyls, alkenyls, halogen, substituted alkyls, aryls, arylhalides, alkoxy and halides. In some embodiments, the three groups are independently selected from halogen, mono or multicyclic (including halosubstituted) aryls, alkyls, and alkenyl compounds and mixtures thereof, preferred are alkenyl groups having 1 to 20 carbon atoms, alkyl groups having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms and aryl groups having 3 to 20 carbon atoms (including substituted aryls). In other embodiments, the three groups are alkyls having 1 to 4 carbon groups, phenyl, naphthyl or mixtures thereof. In further embodiments, the three groups are halogenated, specifically fluorinated, aryl groups. In even further embodiments, the neutral stoichiometric activator is tris(perfluorophenyl)boron or tris(perfluoronaphthyl)boron.

Ionic stoichiometric activator compounds may contain an active proton, or some other cation associated with, but not coordinated to, or only loosely coordinated to, the remaining ion of the ionizing compound. Such compounds and the like are described in European publications EP0570982A1, EP0520732A1, EP0495375A1, EP0500944B1, EP0277003A1 and EP0277004A1, and U.S. Pat. Nos. 5,153,157, 5,198,401, 5,066,741, 5,206,197, 5,241,025, 5,384,299 and 5,502,124 and U.S. patent application Ser. No. 08/285,380, filed Aug. 3, 1994, all of which are herein fully incorporated by reference.

Ionic catalysts can be prepared by reacting a Cr compound with some neutral Lewis acids, such as B(C ₆ F ₆ ) ₃ , which upon reaction with the abstractable ligand (X) of the Cr compound forms an anion, such as ([B(C ₆ F ₅ ) ₃ (X)] ⁻ ), which stabilizes the cationic Cr species generated by the reaction. The catalysts can be prepared with activator components which are ionic compounds or compositions.

In some embodiments, compounds useful as an activator component in the preparation of the ionic catalyst systems used in the process of this invention comprise a cation, which is optionally a Brönsted acid capable of donating a proton, and a compatible non-coordinating anion which is capable of stabilizing the active catalyst species which is formed when the two compounds are combined and said anion will be sufficiently labile to be displaced by olefinic substrates or other neutral Lewis bases such as ethers, nitriles and the like. Two classes of compatible non-coordinating anions useful herein have been disclosed in EP0277003A1 and EP0277004A1 published 1988: anionic coordination complexes comprising a plurality of lipophilic radicals covalently coordinated to and shielding a central charge-bearing metal or metalloid core; and, anions comprising a plurality of boron atoms such as carboranes, metallacarboranes and boranes.

In one preferred embodiment, the stoichiometric activators include a cation and an anion component, and may be represented by the following formula:
(L-H) _d ⁺ (A ^d− )

• • where L is a neutral Lewis base; H is hydrogen; (L-H) ⁺ is a Brönsted acid; A ^d− is a non-coordinating anion having the charge d−; and d is an integer from 1 to 3.

The cation component, (L-H) _d ⁺ may include Brönsted acids such as protons or protonated Lewis bases or reducible Lewis acids capable of protonating or abstracting a moiety, such as an alkyl or aryl, from the bulky ligand chromium catalyst precursor, resulting in a cationic transition metal species.

The activating cation (L-H) _d ⁺ may be a Brönsted acid, capable of donating a proton to the transition metal catalytic precursor resulting in a transition metal cation, including ammoniums, oxoniums, phosphoniums, silyliums, and mixtures thereof, specifically ammoniums of methylamine, aniline, dimethylamine, diethylamine, N-methylaniline, diphenylamine, trimethylamine, triethylamine, N,N-dimethylaniline, methyldiphenylamine, pyridine, p-bromo N,N-dimethylaniline, p-nitro-N,N-dimethylaniline, phosphoniums from triethylphosphine, triphenylphosphine, and diphenylphosphine, oxoniums from ethers such as dimethyl ether diethyl ether, tetrahydrofuran and dioxane, sulfoniums from thioethers, such as diethyl thioethers and tetrahydrothiophene, and mixtures thereof. The activating cation (L-H) _d ⁺ may also be a moiety such as silver, tropylium, carbeniums, ferroceniums and mixtures, specifically carboniums and ferroceniums. In one embodiment (L-H) _d ⁺ can be triphenyl carbonium.

The anion component A ^d− includes those having the formula [M ^k+ Q _n ] ^d− wherein k is an integer from 1 to 3; n is an integer from 2-6; n−k=d; M is an element selected from Group 13 of the Periodic Table of the Elements, specifically boron or aluminum, and Q is independently a hydride, bridged or unbridged dialkylamido, halide, alkoxide, aryloxide, hydrocarbyl, substituted hydrocarbyl, halocarbyl, substituted halocarbyl, and halosubstituted-hydrocarbyl radicals, said Q having up to 20 carbon atoms with the proviso that in not more than 1 occurrence is Q a halide. Specifically, each Q is a fluorinated hydrocarbyl group having 1 to 20 carbon atoms, more specifically each Q is a fluorinated aryl group, and most specifically each Q is a pentafluoryl aryl group. Examples of suitable A ^d− also include diboron compounds as disclosed in U.S. Pat. No. 5,447,895, which is fully incorporated herein by reference.

Illustrative, but not limiting examples of boron compounds which may be used as an activating cocatalyst in the preparation of the improved catalysts of this invention are tri-substituted ammonium salts such as:

trimethylammonium tetraphenylborate, triethylammonium tetraphenylborate, tripropylammonium tetraphenylborate, tri(n-butyl)ammonium tetraphenylborate, tri(t-butyl)ammonium tetraphenylborate, N,N-dimethylanilinium tetraphenylborate, N,N-diethylanilinium tetraphenylborate, N,N-dimethyl-(2,4,6-trimethylanilinium)tetraphenylborate, tropillium tetraphenylborate, triphenylcarbenium tetraphenylborate, triphenylphosphonium tetraphenylborate, triethylsilylium tetraphenylborate, benzene(diazonium)tetraphenylborate, trimethylammonium tetrakis(pentafluorophenyl)borate, triethylammonium tetrakis(pentafluorophenyl)borate, tripropylammonium tetrakis(pentafluorophenyl)borate, tri(n-butyl)ammonium tetrakis(pentafluorophenyl)borate, tri(sec-butyl)ammonium tetrakis(pentafluorophenyl)borate, N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, N,N-diethylanilinium tetrakis(pentafluorophenyl)borate, N,N-dimethyl-(2,4,6-trimethylanilinium) tetrakis(pentafluorophenyl)borate, tropillium tetrakis(pentafluorophenyl)borate, triphenylcarbenium tetrakis(pentafluoropheny