Catalyst system for producing polyethylene copolymers in a high temperature solution polymerization process

A catalyst system for producing ethylene copolymers in a high temperature solution process at temperatures higher than 100° C., the catalyst system comprising:

• (i) a metallocene complex of formula (I)
• wherein
• M is Hf;
• each X is independently a hydrogen atom, halogen atom, R3, OR3, OSO2CF3, OCOR3, SR3, NR32, or PR32 group, wherein R3 is a branched or unbranched, cyclic or acyclic, C1-C20-alkyl, C2-C20-alkenyl, C2-C20-alkynyl, C6-C20-aryl, C7-C20-alkylaryl, or C7-C20-arylalkyl radical;
• optionally containing heteroatoms belonging to groups 14-16 or is SiR33, SiHR32, or SiH2R3;
• R are the same or different and are independently selected from the group consisting of linear or branched C1-C6 alkyl, C6-C10 aryl, C6-C20 alkylaryl, or C6-C20 arylalkyl groups, which do not contain heteroatoms or silicon atoms;
• R1 is a C6 aryl group, which does not contain heteroatoms or silicon atoms;
• R2 is a C4-C10 cycloalkyl group of formula (II),
• wherein
• R′ are the same or different and are independently selected from the group consisting of hydrogen and linear or branched C1-C6 alkyl or C6-C10 aryl;
• and
• n is 1 to 7;
• and
• (ii) a boron containing cocatalyst;
• wherein the catalyst system is a homogeneous or non-supported catalyst system.