Dimethylmagnesium
Chemical compound
From Wikipedia, the free encyclopedia
Dimethylmagnesium is an organomagnesium compound with the chemical formula (CH3)2Mg. It is a white pyrophoric solid.[1][2] Dimethylmagnesium is used in the synthesis of organometallic compounds.
 | |
| Names | |
|---|---|
| IUPAC name
Dimethylmagnesium | |
| Identifiers | |
3D model (JSmol) |
|
| ChemSpider | |
PubChem CID |
|
| UNII | |
CompTox Dashboard (EPA) |
|
| |
| |
| Properties | |
| (CH3)2Mg | |
| Molar mass | 54.375 g·mol−1 |
| Appearance | White solid |
| Density | 0.96 g/cm3 |
| Reacts | |
| Related compounds | |
Related compounds |
|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
| |
Preparation
Like other dialkylmagnesium compounds, dimethylmagnesium is prepared by adding dioxane to a solution of methylmagnesium halide:[3]
- 2 CH3MgX + 2 dioxane ⇌ (CH3)2Mg + MgX2(μ-dioxane)2↓
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.[4] This precipitation drives the Schlenk equilibrium toward (CH3)2Mg. Related methods have been applied to other dialkylmagnesium compounds.[5]
Dimethylmagnesium can also be prepared by combining dimethylmercury and magnesium.[6][7]
Calcium metal, magnesium metal and methyl iodide reacts in diethyl ether to produce dimethylmagnesium.[6]
- Ca + Mg + 2 CH3I → CaI2 + (CH3)2Mg
Properties
Single crystals can be obtained by recrystallization of crude dimethylmagnesium from trimethylgallium.[3] 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.[3][8]