The magnesium imide complexes [(ArNMg center dot diox)(4)center dot 3(diox)] (4) and [(ArNMg center dot THF)(4)center dot tol] (5) (where Ar = 2,4,6-Cl3C6H2, diox = 1,4-dioxane, and THF = tetrahydrofuran) were prepared by the equimolar reaction of Bu2Mg with the primary amine in suitable solvent mixtures. The successful synthesis of the halide-substituted imides is notable because similar reactions with the less acidic organo-substituted anilines cease upon monodeprotonation. Both 4 and 5 form unusual Mg4N4 cubane aggregates in the solid state. Computational studies (HF/6-31G*) indicate that a combination of sterics and metal solvation determines the aggregation state adopted.