Amido ansa 3-substituted indenyl complex precursors can be activated with methylaluminoxane and used for prepolymerization with ethylene to give a heterogeneous catalyst for olefin polymerization. Homo polymerization of ethylene with 1-(3-pent-4-enylindenylidene) dimethylsilyl'-butylamidotitaniumdichloride (1), 1-(3-hex-5-enylindenylidene)dimethylsilyl'butylamidotitanium-dichloride (2), and 1-(3-pent-4-enylindenylidene) (oct-7-enyl)methylsilyl'butylamidotitaniumdichloride (3) produces polyethylenes that contain ethyl branches. The ethyl branching in the polymers made with complexes 1 and 2 is barely above the C-13 NMR detection limit, but the level observed in the polymer made with complex 3 is 17 times greater. Copolymerization of ethylene and 1-hexene using prepolymerized 3 yields copolymers containing both ethyl and butyl branches. (c) 2006 Wiley Periodicals, Inc.