Catalysts containing N-pyrrolyl substituted nitrogen donors

Abstract

Catalyst compositions useful for the polymerization or oligomerization of olefins are disclosed. Certain of the catalyst compositions comprise N-pyrrolyl substituted nitrogen donors. Also disclosed are processes for the polymerization or oligomerization of olefins using the catalyst compositions.

1 - 15 . (canceled).  
     
     
         16 . A catalyst composition for the polymerization or oligomerization of olefins, comprising either (i) a cationic Group 8-10 transition metal complex of a neutral bidentate ligand selected from Set 3, or a tautomer thereof, and a weakly coordinating anion X − , or (ii) the reaction product of Ni(1,5-cyclooctadiene) 2 , B(C 6 F 5 ) 3 , one or more olefin monomers, and a neutral bidentate ligand selected from Set 3:  
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
       wherein: 
 R 2a-f,x-z  are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; R 2a-f  may also be silyl, boryl, or ferrocenyl; in addition, any two of R 2a-d , or R 2x  and R 2y , may be linked by a bridging group;  
 R 3a-j  are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R 3a-j  may be linked by a bridging group;  
 R 4a  and R 4b  are each independently hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; in addition, R 4a  and R 4b  may be linked by a bridging group;  
 G 1  is hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl;  
 G 1 , C, and N collectively comprise a 5- or 6-membered heterocyclic ring;  
 G 2  is hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl;  
 G 2 , V 1 , N, and N collectively comprise a 5- or 6-membered heterocyclic ring;  
 V 1  is CR 3j , N, or PR 4a R 4b ;  
 E 1  is O, S, Se, or NR 2e ;  
 E 2  and E 3  are O, S, or NR 2e ; and  
 Q is C—R 3j , PR 4a R 4b , S(E 2 )(NR 2e R 2f ), or S(E 2 )(E 3 R 2e );  
 provided that the ligand is not of the formula a15.  
 
     
     
         17 . A process for the polymerization or oligomerization of olefins, which comprises contacting one or more olefins with the catalyst composition of  claim 16 .  
     
     
         18 . A ligand selected from Set 4:  
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
       wherein: 
 R 2a-f,x-z  are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; R 2a-f  may also be silyl, boryl, or ferrocenyl; in addition, any two of R 2a-d , or R 2x  and R 2y , may be linked by a bridging group;  
 R 3a-j  are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R 3a-j  may be linked by a bridging group;  
 R 4a  and R 4b  are each independently hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; in addition, R 4a  and R 4b  may be linked by a bridging group;  
 G 1  is hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl;  
 G 1 , C, and N collectively comprise a 5- or 6-membered heterocyclic ring;  
 G 2  is hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl;  
 G 2 , V 1 , N, and N collectively comprise a 5- or 6-membered heterocyclic ring;  
 V 1  is CR 3j , N, or PR 4a R 4b ;  
 E 1  is O, S, Se, or NR 2e ;  
 E 2  and E 3  are O, S, or NR 2e ; and  
 Q is C—R 3j , PR 4a R 4b , S(E 2 )(NR 2e R 2f ), or S(E 2 )(E 3 R 2e );  
 provided that (i) the ligand is not of the formula a15, (ii) when the ligand is of the formula b7, and E 3  is O, R 3a-d  are H, and R 2x  is H, the pyrrolyl group is other than N-carbazolyl, N-(3-phenylindenyl) or unsubstituted N-pyrrolyl, and (iii) when the ligand is of formula a55, it is other than carbazol-9-yl-quinolin-2-ylmethylene-amine.  
 
     
     
         19 . A catalyst composition for the polymerization or oligomerization of olefins, comprising a metal complex ligated by a monoanionic bidentate ligand, 
 wherein at least one of the donor atoms of the ligand is a nitrogen atom substituted by a 1-pyrrolyl or substituted 1-pyrrolyl group;    wherein the remaining donor atoms of the ligand are selected from the group consisting of C, N, P, As, O, S, and Se; and    wherein the metal in said metal complex is selected from the group consisting of Co, Ni, and Pd.    
     
     
         20 . The catalyst composition according to  claim 19  wherein said metal is Ni.  
     
     
         21 . The catalyst composition according to  claim 20 , wherein the metal complex is a compound of formula XII:  
       
         
           
           
               
               
           
         
       
       wherein: 
 M is nickel;  
 D 1 , D 2 , and G collectively comprise the monoanionic bidentate ligand;  
 D 1  and D 2  are monodentate donors linked by a bridging group G, wherein at least one of D 1  and D 2  is ligated to the metal M by a nitrogen atom substituted by a 1-pyrrolyl or a substituted 1-pyrrolyl group;  
 T is H, hydrocarbyl, substituted hydrocarbyl, or other group capable of inserting an olefin; and  
 L is an olefin or a neutral donor group capable of being displaced by an olefin; in addition, T and L may be taken together to form a π-allyl or π-benzyl group.  
 
     
     
         22 . The catalyst composition according to  claim 21 , wherein the monoanionic bidentate ligand is selected from the compounds shown in Set 5, or a tautomer thereof:  
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
       wherein: 
 R 2x-z  are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl;  
 R 3a-j  are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R 3a-j  may be linked by a bridging group;  
 R 4a  and R 4b  are each independently hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; in addition, R 4a  and R 4b  may be linked by a bridging group;  
 E 2  and E 3  are O, S, or NR 2x ; and  
 Q is C—R 3j , PR 4a R 4b , S(E 2 )(NR 2y R 2z ), or S(E 2 )(E 3 R 2x ).  
 
     
     
         23 . The catalyst composition according to  claim 22 , which is attached to a solid support.  
     
     
         24 . A process for the polymerization or oligomerization of olefins, which comprises contacting one or more olefins with the catalyst composition of  claim 19 .  
     
     
         25 . A catalyst composition for the Polymerization or oligomerization of olefins, comprising a metal complex ligated by a neutral tridentate ligand, 
 wherein at least one of the donor atoms of the ligand is a nitrogen atom substituted by a 1-pyrrolyl or substituted 1-pyrrolyl group;    wherein the remaining donor atoms of the ligand are selected from the group consisting of C, N, P, As, O, S, and Se; and    wherein the metal in said metal complex is selected from the group consisting of Mn, Fe, Ru, and Co.    
     
     
         26 . The catalyst composition according to  claim 25 , wherein the metal is Fe or Co.  
     
     
         27 . The catalyst composition according to  claim 26 , wherein the metal complex is a compound of formula XIII:  
       
         
           
           
               
               
           
         
       
       wherein: 
 M is Co or Fe;  
 D 1-3  are monodentate donors which are linked by a bridging group or groups to collectively comprise the neutral tridentate ligand, wherein at least one of D 1 , D 2 , and D 3  is ligated to the metal M by a nitrogen atom substituted by a 1-pyrrolyl or a substituted 1-pyrrolyl group;  
 T is H, hydrocarbyl, substituted hydrocarbyl or other group capable of inserting an olefin;  
 L is an olefin or a neutral donor group capable of being displaced by an olefin;  
 in addition, T and L may be taken together to form a π-allyl or π-benzyl group; and  
 X −  is a weakly coordinating anion.  
 
     
     
         28 . The catalyst composition according to  claim 27 , wherein the neutral tridentate ligand is selected from Set 6, or a tautomer thereof:  
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
       wherein: 
 R 2c,x-z  are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; in addition, in the ligand of formula h6, R 2x  and R 2y  may be linked by a bridging group;  
 R 3a-m  are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R 3a-m  may be linked by a bridging group;  
 R 4a-d  are each independently hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; in addition, any two of R 4a-z  may be linked by a bridging group or groups;  
 G 3  is hydrocarbyl or substituted hydrocarbyl;  
 E 2  and E 3  are O, S, or Se; and  
 E 4  is O, S, or Se.  
 
     
     
         29 . The catalyst composition according to  claim 25 , which is attached to a solid support.  
     
     
         30 . The catalyst composition according to  claim 29 , wherein the solid support is silica.  
     
     
         31 . A process for the polymerization or oligomerization of olefins, which comprises contacting one or more olefins with the catalyst composition of  claim 25 .  
     
     
         32 . The process according to  claim 31 , wherein linear α-olefins are obtained.  
     
     
         33 . The process according to  claim 31 , wherein a polyolefin wax is obtained.  
     
     
         34 . A process for the polymerization of olefins, which comprises contacting one or more olefins with the catalyst composition of  claim 29 .  
     
     
         35 . A catalyst composition for the polymerization or oligomerization of olefins, comprising a metal complex ligated by a dianionic bidentate ligand, 
 wherein at least one of the donor atoms of the ligand is a nitrogen atom substituted by a 1-pyrrolyl or substituted 1-pyrrolyl group;    wherein the remaining donor atoms of the ligand are selected from the group consisting of C, N, P, As, O, S, and Se; and    wherein the metal in said metal complex is selected from the group consisting of Ti, Zr, and Hf.    
     
     
         36 . The catalyst composition according to  claim 35 , wherein the metal complex is a compound of formula XIV:  
       
         
           
           
               
               
           
         
       
       wherein: 
 M is Zr or Ti;  
 D 1 , D 2 , and G collectively comprise the dianionic bidentate ligand;  
 D 1  and D 2  are monodentate donors linked by a bridging group G, wherein at least one of D 1  and D 2  is ligated to the metal M by a nitrogen atom substituted by a 1-pyrrolyl or a substituted 1-pyrrolyl group;  
 T is H, hydrocarbyl, substituted hydrocarbyl, or other group capable of inserting an olefin;  
 L is an olefin or a neutral donor group capable of being displaced by an olefin;  
 in addition, T and L may be taken together to form a π-allyl or π-benzyl group; and  
 X −  is a weakly coordinating anion.  
 
     
     
         37 . The catalyst composition according to  claim 36 , wherein the dianionic bidentate ligand is selected from Set 7, or a tautomer thereof:  
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
       wherein: 
 R 3a-h  are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R 3a-h  may be linked by a bridging group; and  
 G 4  is a divalent bridging hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl.  
 
     
     
         38 . The catalyst composition according to  claim 35 , which is attached to a solid support.  
     
     
         39 . A process for the polymerization of olefins, which comprises contacting one or more olefins with the catalyst composition of  claim 35 .  
     
     
         40 . A catalyst composition for the polymerization or oligomerization of olefins, comprising a metal complex ligated by a monoanionic bidentate ligand, 
 wherein at least one of the donor atoms of the ligand is a nitrogen atom substituted by a 1-pyrrolyl or substituted 1-pyrrolyl group;    wherein the remaining donor atoms of the ligand are selected from the group consisting of C, N, P, As, O, S, and Se; and    wherein the metal in said metal complex is selected from the group consisting of Ti, Zr, and Hf.    
     
     
         41 . The catalyst composition according to  claim 40 , wherein the metal complex is a compound of formula XV:  
       
         
           
           
               
               
           
         
       
       wherein: 
 M is Ti, Zr, or Hf;  
 m and n are integers, defined as follows: when M is Ti and m is 1, n is 2 or 3; when M is Ti and m is 2, n is 1 or 2; when M is Zr and m is 1, n is 3; when M is Zr and m is 2, n is 2; when M is Hf, m is 2 and n is 2;  
 R 3a-i  are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, silyl, boryl, fluoro, chloro, bromo, or nitro, with the proviso that R 3e  is not halogen or nitro; in addition, any two of R 3a-i  on the same or different N-pyrrolyliminophenoxide ligand may be linked by a bridging group;  
 Z is H, halogen, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, silyl, allyl, benzyl, alkoxy, carboxylate, amido, nitro, or trifluoromethane sulfonyl; each Z may be the same or different and may be taken together to form sulfate, oxalate, or another divalent group; and  
 when n is 2 or 3, the metal complex may be a salt, comprising a Ti, Zr, or Hf centered cation with one of the groups Z being a weakly coordinating anion.  
 
     
     
         42 . The catalyst composition according to  claim 40 , wherein the monoanionic bidentate ligand is selected from Set 8, or a tautomer thereof:  
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
       wherein: 
 R 2x  is H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; and  
 R 3a-d,f-i  are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R 3a-d,f-i  may be linked by a bridging group.  
 
     
     
         43 . The catalyst composition according to  claim 42 , which is attached to a solid support.  
     
     
         44 . A process for the polymerization of olefins, which comprises contacting one or more olefins with the catalyst composition of  claim 40 .  
     
     
         45 . A catalyst composition for the polymerization or oligomerization of olefins, comprising a metal complex ligated by a monodentate dianionic ligand, 
 wherein at least one of the donor atoms of the ligand is a nitrogen atom substituted by a 1-pyrrolyl or substituted 1-pyrrolyl group;    wherein the remaining donor atoms of the ligand are selected from the group consisting of C. N, P, As, O, S, and Se; and    wherein the metal in said metal complex is selected from the group consisting of Cr, Mo, and W.    
     
     
         46 . The catalyst composition according to  claim 45 , wherein the metal complex is a compound of formula XVI:  
       
         
           
           
               
               
           
         
       
       wherein: 
 M is Cr, Mo, or W;  
 D 1  and D 2  are monodentate dianionic ligands that may be linked by a bridging group to collectively comprise a bidentate tetraanionic ligand;  
 Z 1a  and Z 1b  are each, independently H, halogen, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, silyl, allyl, benzyl, alkoxy, carboxylate, amido, nitro, trifluoromethanesulfonyl, or may be taken together to form sulfate, oxalate, or another divalent group; and wherein  
 the metal complex may be a salt, comprising a Cr, Mo, or W centered cation with one of Z 1a  and Z 1b  being a weakly coordinating anion.  
 
     
     
         47 . The catalyst composition according to  claim 46 , wherein the metal is Cr and the monodentate dianionic ligand is selected from Set 9, or a tautomer thereof:  
       
         
           
           
               
               
           
         
       
       wherein: 
 R 3a-d  are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R 3a-d  may be linked by a bridging group.  
 
     
     
         48 . The catalyst composition according to  claim 47 , which is attached to a solid support.  
     
     
         49 . A process for the polymerization or oligomerization of olefins, which comprises contacting one or more olefins with the catalyst composition of  claim 45 .  
     
     
         50 . A catalyst composition for the polymerization or oligomerization of olefins, comprising a metal complex ligated by a monodentate dianionic ligand, 
 wherein at least one of the donor atoms of the ligand is a nitrogen atom substituted by a 1-pyrrolyl or substituted 1-pyrrolyl group:    wherein the remaining donor atoms of the ligand are selected from the group consisting of C, N, P, As, O, S, and Se; and    wherein the metal in said metal complex is selected from the group consisting of V, Nb, and Ta.    
     
     
         51 . The catalyst composition according to  claim 50 , wherein the metal complex is a compound of formula XVII:  
       
         
           
           
               
               
           
         
       
       wherein: 
 M is V, Nb, or Ta;  
 R 3a-d  are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, silyl, boryl, fluoro, chloro, bromo, or nitro; in addition, any two of R 3a-d  may be linked by a bridging group;  
 T 1b  is hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, cyclopentadienyl, substituted cyclopentadienyl, N(hydrocarbyl) 2 , O(hydrocarbyl), or halide; in addition, R 3a-3d  and T 1b  may be linked by a bridging group to form a bidentate or multidentate ligand;  
 Z 1a  and Z 1b  are each, independently H, halogen, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, silyl, allyl, benzyl, alkoxy, carboxylate, amido, nitro, trifluoromethane sulfonyl, or may be taken together to form sulfate, oxalate, or another divalent group; and  
 the metal complex may be a salt, comprising a V, Nb, or Ta centered cation with one of Z 1a  and Z 1b  being a weakly coordinating anion.  
 
     
     
         52 . The catalyst composition according to  claim 51 , wherein the monodentate dianionic ligand is selected from Set 10, or a tautomer thereof, and T 1b  is a N(hydrocarbyl) 2  group:  
       
         
           
           
               
               
           
         
       
       wherein: 
 R 3a-d  are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R 3a-d  may be linked by a bridging group.  
 
     
     
         53 . The catalyst composition according to  claim 52 , wherein M is V.  
     
     
         54 . The catalyst composition according to  claim 50 , which is attached to a solid support.  
     
     
         55 . A process for the polymerization of olefins, which comprises contacting one or more olefins with the catalyst composition of  claim 50 .  
     
     
         56 . A catalyst composition for the Polymerization or oligomerization of olefins, comprising a metal complex ligated by a mono- or dianionic ligand comprising a nitrogen donor substituted by a 1-pyrrolyl or substituted 1-pyrrolyl group, 
 wherein said nitrogen donor is linked by a bridging group to a cyclopentadienyl, phosphacyclopentadienyl, pentadienyl, 6-oxacyclohexadienyl, or borataaryl group which is also ligated to the metal in said metal complex;    wherein the remaining donor atoms of the ligand are selected from the group consisting of C, N, P, As, O, S, and Se; and    wherein the metal in said metal complex is selected from the group consisting of Ti, Zr, and Hf.    
     
     
         57 . The catalyst composition according to  claim 56 , wherein the mono- or dianionic ligand is selected from Set 11, or a tautomer thereof:  
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
       wherein: 
 R 2a  is H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, silyl, boryl, or ferrocenyl;  
 R 3a-i  are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R 3a-i  may be linked by a bridging group;  
 R 4a  is hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; and  
 G is a divalent bridging hydrocarbyl, substituted hydrocarbyl, silyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl.  
 
     
     
         58 . The catalyst composition according to  claim 56 , which is attached to a solid support.  
     
     
         59 . A process for the polymerization olefins, which comprises contacting one or more olefins with the catalyst composition of  claim 56 .  
     
     
         60 . A process for the polymerization or oligomerization of olefins, comprising contacting a Group 8-10 transition metal catalyst composition with one or more olefins, wherein said catalyst composition exhibits improved thermal stability, wherein said metal complex comprises a bidentate or variable denticity ligand comprising one or two nitrogen donor atom or atoms substituted by an aromatic or heteroaromatic ring, and wherein the ortho positions of said ring are substituted by groups other than H or alkyl; provided that at least one of the ortho positions of at least one of said aromatic or heteroaromatic rings is substituted by an aryl or heteroaryl group.  
     
     
         61 . A process for the polymerization or oligomerization of olefins, comprising contacting a Group 8-10 transition metal catalyst composition with one or more olefins, wherein said catalyst composition exhibits improved stability in the presence of an amount of hydrogen effective to achieve chain transfer, wherein said metal complex comprises a bidentate or variable denticity ligand comprising one or two nitrogen donor atom or atoms substituted by an aromatic or heteroaromatic ring, and wherein the ortho positions of said ring are substituted by groups other than H or alkyl.  
     
     
         62 . A process for the polymerization or oligomerization of olefins, comprising contacting a Group 8-10 transition metal catalyst composition with one or more olefins, wherein said catalyst composition exhibits either improved thermal stability, or exhibits improved stability in the presence of an amount of hydrogen effective to achieve chain transfer, or both, wherein said metal complex comprises a bidentate or variable denticity ligand comprising one or two nitrogen donor atom or atoms substituted by an aromatic or heteroaromatic ring, wherein at least one of the ortho positions of at least one of said aromatic or heteroaromatic rings is substituted by an aryl or heteroaryl group which is capable of reversibly forming an agostic bond to said Group 8-10 transition metal under olefin polymerization reaction conditions.  
     
     
         63 . A process for the polymerization or oligomerization of olefins, comprising contacting a Group 8-10 transition metal catalyst composition with one or more olefins, wherein said catalyst composition exhibits either improved thermal stability, or exhibits improved stability in the presence of an amount of hydrogen effective to achieve chain transfer, or both, wherein said composition comprises a bidentate or variable denticity ligand comprising one or two nitrogen donor atom or atoms substituted by an aromatic or heteroaromatic ring, wherein the ortho positions of said ring are substituted by groups other than H or alkyl; provided that at least one of the ortho positions of at least one of said aromatic or heteroaromatic ring is substituted by an aryl or heteroaryl group.  
     
     
         64 . The process according to  claim 60 , wherein the ortho positions of said ring are substituted by aryl or heteroaryl groups.  
     
     
         65 . The process according to  claim 60 , wherein the half-life for thermal decomposition is greater than 10 min in solution at 60° C., 200 psig ethylene, and the average apparent catalyst activity of said catalyst is greater than 100,000 mol C 2 H 4 /mol catalyst/h.  
     
     
         66 . The process according to  claim 65 , wherein the half-life for thermal decomposition is greater than 20 minutes, and the average apparent catalyst activity of said catalyst is greater than 1,000,000 mol C 2 H 4 /mol catalyst/h.  
     
     
         67 . The process according to  claim 65 , wherein the half-life for thermal decomposition of said catalyst is greater than 30 min.  
     
     
         68 . The process according to  claim 60 , wherein the half-life for thermal decomposition is greater than 5 min in solution at 80° C., 200 psig ethylene, and the average apparent catalyst activity of said catalyst is greater than 100,000 mol C 2 H 4 /mol catalyst/h.  
     
     
         69 . The process according to  claim 60 , wherein the process temperature is between about 60 and about 150° C.  
     
     
         70 . The process according to  claim 69 , wherein the process temperature is between about 100 and about 150° C.  
     
     
         71 . The process according to  claim 60 , wherein the bidentate or variable denticity ligand is selected from Set 12:  
       
         
           
           
               
               
           
         
       
       wherein: 
 R 6a  and R 6b  are each independently an aromatic or heteroaromatic ring wherein the ortho positions of said ring are substituted by groups other than H or alkyl; provided that at least one of the ortho positions of at least one of said aromatic or heteroaromatic rings is substituted by an aryl or heteroaryl group;  
 and R 2x  and R 2y  are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl, and may be linked by a bridging group.  
 
     
     
         72 . The process according to  claim 71 , wherein the Group 8-10 transition metal is nickel and the bidentate or variable denticity ligand is selected from Set 13:  
       
         
           
           
               
               
           
         
       
       wherein: 
 R 7a-d  are groups other than H or alkyl; provided that at least one of R 7a-d  is an aryl or heteroaryl group;  
 R 2x  and R 2y  are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl, and may be linked by a bridging group; and  
 R 3a-f  are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, fluoroalkyl, silyl, boryl, fluoro, chloro, bromo, cyano, or nitro; in addition, any two of R 3a-f  may be linked by a bridging group.  
 
     
     
         73 . The process according to  claim 72 , wherein the composition is attached to a solid support.  
     
     
         74 . The process according to  claim 73 , wherein the process temperature is between about 60 and about 100° C.