[M((P3C2Bu2)-Bu-t)(CO)(3)I] (M = Mo, 1, W, 2) have been synthesised and reacted with PCl5 for oxidation study purposes. Compounds Ti((P3C2Bu2)-Bu-t)(Ind)Cl-2], 3, and [Zr((P3C2Bu2)-Bu-t)(Cp)Cl-2], 4, were detected spectroscopically, but showed to be too unstable to be isolated. A Ti(IV) complex, [Ti((P3C2Bu2)-Bu-t)Cl-3], 5, has been formed from the reaction of [TiCl4] with the base-free ligand K((P3C2Bu2)-Bu-t), while the Ti(III) species, [Ti((P3C2Bu2)-Bu-t) Cl-2(THF)], 6, was prepared from [TiCl3(THF)(3)]. Compounds 5 and 6 were studied as ethylene catalyst precursors after activation with MAO. In the studied conditions, complex 5 is the most active one with an activity of 2.2 x 10(5) g(molTi [E] h) (1), one order of magnitude higher than compound 6. The produced polymer is linear polyethylene.