For the Mg analogue, a large ΔG value (-32.9 kcal/mol) is obtained from the conformation with two mesityl substituents below the coordination plane and one situated above. Conversely, a smaller ΔG value (-16.8 kcal/mol) is obtained by adopting a conformation where all three mesityl substituents are positioned above the coordination plane as seen in 3-Ca. The latter is more in line with the energies calculated for the [AE{N(SiMe3)}3] -/2-series, thus highlighting the role played by the ligand substituents and their conformations in the stability of reduced species. Owing to the results obtained with trigonal planar AE tris-amide complexes, we postulated that a more generalised equatorial ligand field could induce an increase in d-character for the LUMO of divalent Ca, Sr and Ba complexes, thus opening more possibilities in terms of ligand design. To verify this, we turned our attention towards complexes featuring a square planar coordination geometry. Square planar Mg(II) porphyrin complexes are relatively common, owing to the rigid conformation of the ligand dictating the geometry around the metal center; however, these species are not suitable for our molecular design because of the redox activity of porphyrins and their incompatibility with large AE metals. Besides constrained square planar porphyrin complexes, a square planar geometry is a very rare coordination mode for the AE metals owing to the lack of crystal field stabilization. As a result there are a handful of near square planar magnesium complexes supported by nitrogen-based ligands in the literature, and, to the best of our knowledge, only one example of a heavy AE complex in a square planar geometry, [Sr{N(SiMe3)2}2(dioxane)2]n (4) reported by Lappert and co-workers. Therefore, we decided to use 4 as a model for expanding our strategy through computational studies. Gratifyingly, MO analysis affords a LUMO with d-character, which was also confirmed by NBO calculations (d%1. ); and in this case, this structural puckering seems necessary to accommodate the presence of the additional charge.