Diethylamidotitanium trichloride reacts with a variety of bulky amidines ArN(H)C(Ar′)NAr [Ar = 2,6-diisopropylphenyl; Ar′ = Ph, p-Me2NC6H4, p-MeOC6H4, p-(2,5-dimethylpyrrole)C6H4] to form ammonium titanates. These new titanium complexes undergo polyethylenyl chain transfer polymerization to aluminium alkyls after activation with d-MAO (“dry methylaluminoxane”). Ethylene is polymerized with an activity of up to 1000 kgPE molcat–1 h–1 bar–1 in the presence of 1000 equiv. of triethylaluminium. Linear aluminium-terminated polyethylene is the only product observed. This polymerization process can be viewed as an efficient catalytic version of Ziegler's “Aufbaureaktion”.