Patent ID: 8404915

Claim:
A method to selectively oligomerize an olefin comprising contacting the olefin with a composition comprising: 1) at least one ligand characterized by the general formula: wherein P is phosphorus; each of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , and R 16 is independently, selected from the group consisting of hydrogen, halogen, optionally substituted hydrocarbyl and optionally substituted heteroatom containing hydrocarbyl; each of Z 1 , Z 2 , Z 3 , and Z 4 is, independently, selected from a first group consisting of hydrogen, a hydrocarbyl, alkoxy, aryloxy, alkylthio, arylthio, hydroxyl, mercapto and amino; T is a bridging group selected from the group consisting of optionally substituted hydrocarbyl having from 1 to 20 carbon atoms; 2) a metal precursor characterized by the general formula Cr(L) n where each L is independently selected from the group consisting of, mesityl, tetrahydrofuran, methyl, ethyl, butyl, pentyl, hexyl, octyl, phenyl, Et 2 O, NH 3 , NMe 3 , acetylacetonate, 2-ethylhexanoate, neopentyl, SMe 2 , CH 2 —C 6 H 4 -o-NMe 2 , trifluoroacetate, CH(SiMe 3 ) 2 , diisopropylamide, picolinate, or NO 3 , where Et is ethyl and Me is methyl, and wherein two or more L groups may be combined in a ring structure having from 3 to 50 non-hydrogen atoms; n is 3, 4, 5, or 6; and 3) optionally, one or more activators, and wherein at least two and less than all four of Z 1 , Z 2 , Z 3 , and Z 4 are selected from a second group consisting of alkoxy, aryloxy, alkylthio, arylthio, hydroxyl, mercapto, and amino, and Z 1 , Z 2 , Z 3 , and Z 4 may not all be methoxy, and either of the pairs of Z 1 and Z 2 or Z 3 and Z 4 are not both selected from the second group, wherein either both of Z 2 and Z 3 or both of Z 1 and Z 4 are selected from the second group.