In this work, we investigated precursors and procatalysts with well-defined crystal structures and morphologies in ZieglerNatta systems to improve our understanding of the nature of the active metal sites. Molecular cluster precursors such as [Mg4Ti3(mu(6)-O)(mu(3)-OH)(3)(mu-OEt)(9)(OEt)(3)(EtOH)(3)Cl-3], [Mg4Ti3(mu(6)-O)(mu(3)-OH)(mu(3)-OEt)(2)(mu-OEt)(9)(OEt)(3)(EtOH)(3)Cl-3], and [Mg6Ti4(mu(6)-O)(2)(mu(3)-OH)(4)(mu- OEt)(14)(OEt)(4)(EtOH)(2)Cl-2] were prepared via simple elimination of the cyclopentadienyl ring from Cp2TiCl2 as CpH in the presence of magnesium metal and ethanol. Titanocene dichloride acts as both a source of titanium and a magnesium-chlorinating agent. The resulting novel complexes were characterized using single-crystal X-ray diffraction. In these compounds, Ti(OEt)(4) molecules are grafted onto Mg-4 and Mg-6 ethoxide cubane-like surfaces; this strongly affects the procatalyst morphology, which is transferred to the polymer. Mg-4(OR)(8) units act as carriers for the AlR3 co-catalyst, resulting in return of alkyl functions to the Ti center.