Catalyst composition and method for preparing polyethylene

A catalyst composition for polymerizing olefins, the catalyst composition comprising:

• a) a first metallocene compound having the formula:
• wherein
• M1 is hafnium;
• X1 is an indenyl ligand which is substituted at the 1-position with a group selected independently from
• X2 is [1] an unsubstituted cyclopentadienyl ligand or an unsubstituted indenyl ligand, [2] a cyclopentadienyl ligand which is substituted with at least one hydrocarbyl substituent selected independently from a C1-C12 alkyl or a C2-C12 alkenyl, or [3] an indenyl ligand which is substituted at the 1-position with a group having the formula
• wherein X1 and X2 are unbridged;
• and
• X3 and X4 are each a chloride;
• b) optionally, a co-catalyst comprising an organoaluminum compound, an organoboron compound, an organozinc compound, an organomagnesium compound, an organolithium compound, or any combination thereof;
• and
• c) an activator comprising a solid oxide treated with an electron-withdrawing anion (activator-support), an organoboron compound, an organoborate compound, an ionizing ionic compound, an aluminoxane compound, or any combination thereof.