Like other dialkylmagnesium compounds, dimethylmagnesium is prepared by adding dioxane to a solution of methylmagnesium halide:[3] In such procedures, the dimethylmagnesium exists as the ether adduct, not the polymer.

[4] Addition of 1,4-dioxane causes precipitation of solid MgX2(μ-dioxane)2, a coordination polymer.

Related methods have been applied to other dialkylmagnesium compounds.

The material is a polymer with the same connectivity as silicon disulfide, featuring tetrahedral magnesium centres, each surrounded by bridging methyl groups.

[7] The linear chain structure seen for dimethylmagnesium is also observed for diethylmagnesium and dimethylberyllium.