Ziegler-Natta catalysis is a very important industrial process for the production of polyolefins. However, the catalysts are not well understood at the molecular level. Yet atomic-scale structural information is of pivotal importance for rational catalyst development. We applied a solid state NMR/DFT tandem approach to gain detailed insight into the interactions between the catalysts’ support, MgCl₂, and organic electron donors. Due to the heterogeneity of the samples large line widths are observed in the carbon spectra. Despite this, good agreement between experimental and computational values was reached and this showed that 1,3-diethers coordinate on (110)-surface sites, while phthalates are less selective and coordinate on both (104)- and (110)-surface sites.