Imidochromium compounds contained in catalyst systems for olefin polymerization

A catalyst system containing

• (A) at least one imidochromium compound, which can be obtained by a process encompassing the following process steps:
• (a) contacting a dioxochromium compound with an N-sulfinyl compound R1—N═S═O or R2—N═S═O, wherein the variables have the following meaning:
• R1 is C1-C20-alkyl, C2-C20-alkenyl, C6-C20-aryl, alkylaryl having 1 to 10 carbon atoms in the alkyl radical and 6 to 20 carbon atoms in the aryl radical, whereby the organic radical R1 optionally have inert substituents, or SiR33;
• R2 is for R3C═NR4, R3C═O, C═O(OR4), R3C═S, (R3)2P═O, (OR3)2P═O, SO2R3, R3R4C═N, NR3R4 or BR3R4;
• R3 and R4 independent of each other, are C1-C20-alkyl, C2-C20-alkenyl, C6-C20-aryl, alkylaryl having 1 to 10 carbon atoms in the alkyl radical and 6 to 20 carbon atoms in the aryl radical, hydrogen if the latter is bonded to a carbon atom, whereby the organic radicals R3 and R4 can also have inert substituents;
• (b) contacting the reaction product thus obtained with chlorine if a sulfinyl compound R1—N═S═O was used and, in case an N-sulfinyl compound R2—N═S═O was used, with chlorine of sulfurylchloride or with no other reagent;
• (B) at least one activator compound and
• (C) optionally, one or more additional catalysts.