Patent ID: 7297832

Claim:
A process for the oligomerisation of olefins comprising contacting an olefinic feedstream with a catalyst system which includes the combination of: a transition metal compound; and a heteroatomic ligand described by the following general formula (R) n A-B—C(R) m where A and C are independently an atom selected from the group consisting of phosphorus, arsenic, antimony, oxygen, bismuth, sulphur, selenium and nitrogen or said atom oxidized by S, Se, N or O, where the valance of A and/or C allows for such oxidation; B is a linking group between A and C; the R groups are the same or different and each R is independently selected from a homo hydrocarbyl group and a heterohydrocarbyl group, and at least one R has a polar substituent; and n and m for each R is independently determined by the respective valence and oxidation state of A and C; and provided that when the heteroatomic ligand is described by the following general formula (R 1 )(R 2 )A-B—C(R 3 )(R 4 ) wherein A and C are independently selected from the group consisting of phosphorus, arsenic, antimony, bismuth and nitrogen; B is a linking group between A and C; and each of R 1 , R 2 , R 3 and R 4 is independently selected from the group consisting of a non-aromatic group, an aromatic group, and a heteroaromatic group; at least one of R 1 , R 2 , R 3 and R 4 , if aromatic, has a polar substituent on a 2 nd or further atom from the atom bound to A or C and provided that any polar substituents that R 1 , R 2 , R 3 and R 4 may have, if they are aromatic, are not on the atom adjacent to the atom bound to A or C.