Reduction of [Mg(NON)]2 ([NON]2− = [O(SiMe2NDipp)2]2−, Dipp = 2,6-iPr2C6H3) affords Mg(i) species containing NON- and NNO-ligands ([NNO]2− = [N(Dipp)SiMe2N(Dipp)SiMe2O]2−). The products of reactions with iPrNCNiPr and CO are consistent with the presence of reducing Mg(i) centres. Extraction with THF affords [K(THF)2]2[(NNO)Mg–Mg(NNO)] with a structurally characterised Mg–Mg bond that was examined using density functional theory.