In this study, solid state 13C NMR spectroscopy was utilised to characterize and identify the metal–ester coordination in active fourth generation (phthalate) Ziegler–Natta catalysts. It is known that different donors affect the active species in ZN catalysts. However, there is still limited data available of detailed molecular information how the donors and the active species are interplaying. One of the main goals of this work was to get better insight into the interactions of donor and active species. Based on the anisotropy tensor values (δ11, δ22, δ33) from low magic-angle spinning (MAS) 13C NMR spectra in combination with chemical shift anisotropy (CSA) calculations (δaniso and η), both the coordinative metal (Mg/Ti) and the symmetry of this interaction between metal and the internal donor in the active catalyst (MgCl2/TiCl4/electron donor) system could be identified.