Synthesis, Structural Characterization, and Theoretical Studies of Complexes of Magnesium and Calcium with Gallium Heterocycles

The magnesium− and calcium−gallium heterocycle complexes [Mg{Ga[(ArNCH)2]}2(THF)3] and [Ca{Ga[(ArNCR)2]}2(THF)4], R = H or Me, Ar = C6H3Pri2-2,6, have been prepared via the reduction of [I2Ga{(ArNCR)2}] with the group 2 metal in tetrahydrofuran. The mechanisms of the reactions have been elucidated, and the crystal structures of the complexes exhibit the first structurally authenticated Ga−Mg and Ga−Ca bonds in molecular species. Theoretical studies suggest that the heterocycle−group 2 metal interactions have significant ionic character.