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(NPr2i) N( Ar)](-) or {[( Ar) NC( Me)](2)CH}(-), Ar is 2,6- diisopropylphenyl, Me is methyl, and Pr-i is isopropyl) in moderate yields. The results of x- ray crystallographic and theoretical studies are consistent with central Mg-2(2+) 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).