Dimethylmagnesium


Dimethylmagnesium is an organomagnesium compound with the chemical formula. It is a white pyrophoric solid. Dimethylmagnesium is used in the synthesis of organometallic compounds.

Preparation

Like other dialkylmagnesium compounds, dimethylmagnesium is prepared by adding dioxane to a solution of methylmagnesium halide:
In such procedures, the dimethylmagnesium exists as the ether adduct, not the polymer.
Addition of 1,4-dioxane causes precipitation of solid, a coordination polymer. This precipitation drives the Schlenk equilibrium toward. Related methods have been applied to other dialkylmagnesium compounds.
Dimethylmagnesium can also be prepared by combining dimethylmercury and magnesium.
Calcium metal, magnesium metal and methyl iodide reacts in diethyl ether to produce dimethylmagnesium.

Properties

Single crystals can be obtained by recrystallization of crude dimethylmagnesium from trimethylgallium. The structure of this compound has been determined by X-ray crystallography. The material is a polymer with the same connectivity as silicon disulfide, featuring tetrahedral magnesium centres, each surrounded by bridging methyl groups. The Mg-C distances are 223 pm. The Mg-Mg distances are 272 pm.

Related compounds

The linear chain structure seen for dimethylmagnesium is also observed for diethylmagnesium and dimethylberyllium. Dimagnesium is however a dimer.