Catalyst composition and process for oligomerization of ethylene

A catalyst composition, obtainable by combining at least:

• (a) a chromium compound;
• (b) a ligand of the general structure
• (B) R1R2P—N(R3)—P(XR7)R8,
• wherein
• X═O or S, and
• R1, R2, R3, and R8 are independently C1-C10-alkyl, C6-C20-aryl, C3-C10-cycloalkyl, arylalkyl, alkylaryl, or trialkylsilyl, or any cyclic derivatives of (B), wherein at least one of the P or N atoms of the PNP-unit is a member of the ring system, the ring system being formed from one or more constituent compounds of structure (B) by substitution, and wherein R7 is C1-C10-alkyl, C3-C10-cycloalkyl, arylalkyl, or trialkylsilyl;
• and
• (c) an activator or co-catalyst.

A catalyst composition comprising:

• (a) a chromium compound;
• (b) a ligand of the general structure
• (B) R1R2P—N(R3)—P(XR7)R8, with X═O or S, wherein R1, R2, R3, and R8 are independently C1-C10-alkyl, unsubstituted C6-C20-aryl, C3-C10-cycloalkyl, arylalkyl, alkylaryl, or trialkylsilyl, or any cyclic derivatives of (B), wherein at least one of the P or N atoms of the PNP-unit is a member of the ring system, the ring system being formed from one or more constituent compounds of structure (B) by substitution and wherein R7 is C1-C10-alkyl, C3-C10-cycloalkyl, unsubstituted arylalkyl, or trialkylsilyl;
• and
• (c) an activator or co-catalyst.