An Approach to Pin Down the Solid-State Structure of the “Turbo Grignard”

Single crystals of [iPrMgCl­(THF)]2[MgCl2(THF)2]2 were obtained by layering a THF solution of the “turbo Grignard” iPrMgCl·LiCl with Et2O at ambient temperature. The isolated 1:1 Grignard–MgCl2 adduct is isostructural with crystalline compounds which were obtained from pure RMgCl solutions (R = Me, tBu, Ph, Bn). The structure of [iPrMgCl­(THF)]2[MgCl2(THF)2]2 reveals an open-cube motif (monoclinic, P21/c). When dioxane was added to a THF solution of iPrMgCl·LiCl, single crystals of [LiCl­(THF)2]2 and [iPr2Mg­(dioxane)]∞ (monoclinic, C2/c) were isolated. From 1:1 mixtures of (Me3Si)2CHMgCl (DisylMgCl) and LiCl (prepared analogously to iPrMgCl·LiCl) two different Grignard compounds, the monomer [DisylMgCl­(THF)2] (monoclinic, P21) and the dimer [DisylMgCl­(THF)]2 (monoclinic, P21/c), were isolated as single crystals. During our studies, two oxidation products of iPrMgCl and DisylMgCl, respectively, resulting from oxygen insertion, were obtained and structurally characterized. Colorless plates of [iPrMg­(OiPr)]4 (monoclinic, P21/m) grew from a THF/benzene solution. The dimeric alkoxide {[DisylOMgCl]­[LiCl­(THF)2]}2 (monoclinic, C2/c), which was obtained from DisylMgCl·LiCl by oxidation through residual oxygen, displays the only structure in which incorporation of LiCl in the molecular framework of a Mg alkoxide was observed.