Ligand and Coligand Effects on Ion Association in Magnesium Amides

We report here the examination of the effect of ligand bulk and coligand influence on ion association in a family of magnesium amides. Use of the sparsely employed, sterically demanding coligand HMPA (hexamethylphosphoramide, OP(N(Me)2)3, in conjunction with four different silylamides [N(SiMe3)(R)]− (R = SiMe3, C6H5 (Ph), 2,4,6-MesC6H2 (Mes), 2,6-i-Pr2C6H3 (Dipp)) provides unique insight into factors governing ion association. To this effect, we report three contact molecules, along with one example of a rare ion-association state with one amido group metal-bound, whereas the other is unassociated.