Stable Magnesium(I) Compounds with Mg-Mg Bonds

The chemistry of the group 2 metals (beryllium, magnesium, calcium, strontium, and barium) is dominated by the +2 oxidation state. Here, we report the reductions of two magnesium(II) iodide complexes with potassium metal in toluene, leading to thermally stable magnesium(I) compounds, (L)MgMg(L) (where L is [(Ar)NC(NPrⁱ₂)N(Ar)]^- or {[(Ar)NC(Me)]₂CH}^-, Ar is 2,6-diisopropylphenyl, Me is methyl, and Prⁱ is isopropyl) in moderate yields. The results of x-ray crystallographic and theoretical studies are consistent with central Mg₂²⁺ units that have single, covalent magnesium-magnesium bonding interactions with 2.8508 ± 0.0012 (standard deviation) and 2.8457 ± 0.0008 angstrom bond lengths, respectively, and predominantly ionic interactions with the anionic ligands (L).