| abstract |
The present invention relates to a catalyst composition and a process for di-, tri- and/or tetramerization of ethylene, wherein the catalyst composition comprises a chromium compound, a ligand of the general structure (A)R1R2P-N(R3)-P(R4)--N(R5)-H or (B)R1R2P-N(R3-P(R4)-N(R5)-PR6R7, or any cyclic derivatives of (A) and (B), wherein at least one of the P or N atoms of the PNPN-unit or PNPNP -unit is member of a ring system, the ring system being formed from one or more constituent compounds of structures (A) or (B) by substitution and a co-catalyst or activator. |