Dimethylmagnesium Explained
Dimethylmagnesium is an organomagnesium compound. It is a white pyrophoric solid.[1] [2] 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:
2 CH3MgX + 2 dioxane (CH3)2Mg + MgX2(μ-dioxane)2↓In such procedures, the dimethylmagnesium exists as the ether adduct, not the polymer.
Addition of 1,4-dioxane causes precipitation of solid MgX2(μ-dioxane)2, a coordination polymer.[3] This precipitation drives the Schlenk equilibrium toward (CH3)2Mg. Related methods have been applied to other dialkylmagnesium compounds.[4]
Dimethylmagnesium can also be prepared by combining dimethylmercury and magnesium.
Properties
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 224 pm.[5]
Related compounds
The linear chain structure seen for dimethylmagnesium is also observed for diethylmagnesium and dimethylberyllium.[6] Di(tert-butyl)magnesium is however a dimer.[7]
Notes and References
- Arthur C. Cope . Cope . A. C. . The Preparation of Dialkylmagnesium Compounds from Grignard Reagents . J. Am. Chem. Soc. . 1935 . 57 . 11 . 2238–2240 . 10.1021/ja01314a059 .
- Anteunis . M. . Studies of the Grignard Reaction. II. Kinetics of the Reaction of Dimethylmagnesium with Benzophenone and of Methylmagnesium Bromide-Magnesium Bromide with Pinacolone . . 1962 . 27 . 2 . 596–598 . 10.1021/jo01049a060 .
- 10.1002/chem.201903120. Structure–Solubility Relationship of 1,4‐Dioxane Complexes of Di(hydrocarbyl)magnesium . 2019 . Fischer . Reinald . Görls . Helmar . Meisinger . Philippe R. . Suxdorf . Regina . Westerhausen . Matthias . Chemistry – A European Journal . 25 . 55 . 12830–12841 . 31328293 . 7027550 .
- Richard A. Andersen, Geoffrey Wilkinson . Bis[(Trimethylsilyl)Methyl] Magnesium . . 10.1002/9780470132500.ch61 . 1979 . 19 . 262–265 .
- Weiss . E. . Die Kristallstruktur des Dimethylmagnesiums . . 1964 . 2 . 4 . 314–321 . 10.1016/S0022-328X(00)82217-2 .
- Snow . A.I.. Rundle. R.E.. Structure of Dimethylberyllium. Acta Crystallographica. 1951. 4. 4. 348–52. 10.1107/S0365110X51001100. 1951AcCry...4..348S. 2027/mdp.39015095081207. free.
- 10.1021/om030091j . Di- tert -butylmagnesium: Synthesis and Structure . 2003 . Starowieyski . Kazimierz B. . Lewinski . Janusz . Wozniak . Robert . Lipkowski . Janusz . Chrost . Andrzej . Organometallics . 22 . 12 . 2458–2463 .
