This invention relates to the oligomerisation of olefinic compounds in the presence of an activated oligomerisation catalyst. The invention also extends to a particular manner for providing an activated oligomerisation catalyst. According to the present invention, there is provided a process for producing an oligomeric product by the oligomerisation of at least one olefinic compound, the process including (a) providing an activated oligomerisation catalyst by combining, in any order, iii) a source of
chromium, ιv) a ligating compound of the formula (R1)m X1 (Y) X2 (R2)n wherein X1 and X2 are independently an atom selected from the group consisting of
nitrogen,
phosphorus,
arsenic,
antimony,
bismuth,
oxygen, sulphur and
selenium or said atom oxidized by S, Se, N or O where the valence of X1 and / or X2 allows for such oxidation, Y is a linking group between X1 and X2 which linking group contains at least one
nitrogen atom which is directly bonded to X1 or X2, m and n are independently 0, 1 or a larger integer, and R1 and R2 are independently
hydrogen, a hydrocarbyl group, an organoheteryl group or a heterohydrocarbyl group, and the respective R1 groups are the same or different when m>1, and the respective R2 groups are the same or different when n>1, in) a catalyst activator which is an organoboron compound including a cation and a non-coordinating anion of the general formula [(R10)x L*-H]+[B(R20)4]− wherein L* is an atom selected from the group consisting of N, S and P, the cation [(R10)x L*- H]* is a Bronsted acid, x is an integer 1, 2 or 3, each R10 is the same or different when x is 2 or 3 and each is a —H, hydrocarbyl group or a heterohydrocarbyl group, provided that at least one of R10 comprises at least 6 carbon atoms and provided further that the total number of carbon atoms in (R10)x collectively is greater than 12, R20 independently at each occurrence is selected from the group consisting of
hydride, dialkylamido,
halide,
alkoxide, aryloxide, hydrocarbyl, halosubstituted-hydrocarbyl radicals, halosubstituted-
alkoxide, halosubstituted-aryloxide and a halosubstituted aromatic ring
moiety with at least one
halide substituent on the aromatic ring, and vi) an aliphatic
solvent, and (b) contacting the at least one olefinic compound with the activated oligomerisation catalyst to produce an oligomeric product.