To get a better understanding of the Ge-Mg interactions found for 4 and 5, electronic structure calculations were performed (for a detailed description see ESI Section 2.10). NBO analysis indicates that the Ge-Mg interaction in 4, bound to 0-3 THF molecules (structures 4a-4d, respectively), is best described by donation from the Ge lone pair residing in a spherically diffuse donor NBO (s-character = 79.9-86.8%) to a Mg-based acceptor NBO of high s-character (>95%). These dative interactions are consistently stronger than the respective contributions from the N-and O-donors and decrease slightly upon increasing the coordination number of the Mg centre. The dative interaction is equally strong after the observed addition of p-tolylacetylene over the NHGe in 5, albeit with a small decrease of the s-character of the Ge lone pair (73.7%) and delocalisation energy. These results demonstrate that there is a strong, dative Ge-Mg interaction present in both 4 and 5. This is in contrast with our observations for Ge-Zn complex 3 and highlights the versatility of the germylene centre in 2, with the extent of Ge-M dative interactions varying as a function of the required electron density on the metal centre that occupies the redox-active binding pocket.