Catalyst systems that include meta-alkoxy substituted n-aryl bis-diphosphinoamine ligands

1. A catalyst system for tetramerizing ethylene to form 1-octene, the catalyst system comprising:

a catalyst comprising a chromium compound coordinated with a ligand; and

a co-catalyst comprising an organoaluminum compound,

wherein:

the ligand has the chemical structure:

wherein:

R 5 is a (C 1 -C 15 ) alkyl group, a (C 3 -C 15 ) cyclohydrocarbyl group, a (C 3 -C 15 ) cycloheterohydrocarbyl group, or a (C 6 -C 15 ) aryl group, and

R A , R B , R C , R D , R E , R F , R G , R H , R 1 , R 2 , R 3 , R 4 , R 6 , R 7 , R 8 , and R 9 are independently chosen from a hydrogen atom, a (C 1 -C 50 ) hydrocarbyl group, or a (C 1 -C 50 ) heterohydrocarbyl group.

2. The catalyst system of claim 1 , wherein R 5 is an unsubstituted (C 1 -C 15 ) alkyl group.

3. The catalyst system of claim 1 , wherein R 5 is a (C 1 -C 15 ) linear alkyl group.

4. The catalyst system of claim 1 , wherein R 5 is penta-methylene.

5. The catalyst system of claim 1 , wherein R A , R B , R C , R D , R E , R F , R G , and R H are independently chosen from a (C 6 -C 50 ) aryl group.

6. The catalyst system of claim 1 wherein:

R A , R B , R C , R D , R E , R F , R G , and R H are each a phenyl group, and

R 1 , R 2 , R 3 , R 4 , R 6 , R 7 , R 8 , and R 9 are each a hydrogen atom.

7. The catalyst system of claim 1 , wherein the chromium compound comprises one or more of an organic chromium salt, an inorganic chromium salt, a chromium coordination complex, and a chromium organometallic complex.

8. The catalyst system of claim 1 , wherein the chromium compound comprises one or more of chromium trichloride tris-tetrahydrofuran complex, chromium dichloride bis-tetrahydrofuran complex, (benzene)tricarbonyl chromium, chromium (III) octanoate, chromium (III) acetylacetonoate, chromium hexacarbonyl, chromium (III) 2-ethylhexanoate, and chromium (III) 2,2,6,6-tetramethyl-3,5-heptanedionate.

9. The catalyst system of claim 1 , wherein the catalyst comprises the ligand in an amount such that a molar ratio of the ligand to chromium is from 0.1 to 10.0.

10. The catalyst system of claim 1 , wherein the organoaluminum compound has the structure:

wherein R 10 , R 11 , and R 12 are each selected from the group consisting of a hydrogen atom and an unsubstituted (C 1 -C 20 ) linear or branched alkyl group.

11. The catalyst system of claim 1 , wherein the organoaluminum compound comprises one or more of trimethylaluminium, triethylaluminum, tripropylaluminum, tri-iso-butylaluminum, diisobutylaluminium hydride, trihexylaluminum, tri-n-octylaluminium, methylaluminium dichloride, ethylaluminium dichloride, dimethylaluminium chloride, diethylaluminium chloride, aluminium isopropoxide, ethylaluminiumsesquichloride, methylaluminiumsesquichloride, methylaluminoxane, ethylaluminoxane, and modified methylaluminoxane.

12. The catalyst system of claim 1 , wherein the catalyst system comprises the co-catalyst in an amount such that a molar ratio of the organoaluminum compound to the chromium compound is from 100 to 5000.

13. A method for tetramerizing ethylene to form 1-octene, the method comprising contacting ethylene with the catalyst system of claim 1 to form a product comprising 1-octene.

14. The method of claim 13 , wherein the 1-octene is formed in conditions of:

a reactor pressure from 2 bar to 100 bar; and

a reactor temperature from 30° C. to 180° C.

15. The method of claim 13 , wherein ethylene is contacted with the catalyst system in the presence of a reaction medium, wherein the reaction medium comprises one or more of cyclohexane, methylcyclohexane, decahydronapthalene, chlorobenzene, toluene, xylene, heptane, and isooctane.