Dimethylmagnesium

Dimethylmagnesium
Names
IUPAC name
Dimethylmagnesium
Identifiers
3D model (JSmol)
ChemSpider
UNII
  • InChI=1S/2CH3.Mg/h2*1H3; X markN
    Key: KZLUHGRPVSRSHI-UHFFFAOYSA-N X markN
  • C[Mg]C
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).
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Dimethylmagnesium is an organomagnesium compound with the chemical formula (CH3)2Mg. 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:

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. This precipitation drives the Schlenk equilibrium toward (CH3)2Mg. 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 react in diethyl ether to produce dimethylmagnesium.

Ca + Mg + 2 CH3I → CaI2 + (CH3)2Mg

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.

The linear chain structure seen for dimethylmagnesium is also observed for diethylmagnesium and dimethylberyllium. Di(tert-butyl)magnesium is however a dimer.

References

  1. ↑ Cope, A. C. (1935). "The Preparation of Dialkylmagnesium Compounds from Grignard Reagents". J. Am. Chem. Soc. 57 (11): 2238–2240. doi:10.1021/ja01314a059.
  2. ↑ Anteunis, M. (1962). "Studies of the Grignard Reaction. II. Kinetics of the Reaction of Dimethylmagnesium with Benzophenone and of Methylmagnesium Bromide-Magnesium Bromide with Pinacolone". J. Org. Chem. 27 (2): 596–598. doi:10.1021/jo01049a060.
  3. 1 2 3 Stuhl, Christoph; Anwander, Reiner (2018). "Dimethylmagnesium revisited". Dalton Transactions. 47 (36): 12546–12552. doi:10.1039/C8DT01542B. PMID 29790529.
  4. 1 2 Fischer, Reinald; Görls, Helmar; Meisinger, Philippe R.; Suxdorf, Regina; Westerhausen, Matthias (2019). "Structure–Solubility Relationship of 1,4-Dioxane Complexes of Di(hydrocarbyl)magnesium". Chemistry – A European Journal. 25 (55): 12830–12841. Bibcode:2019ChEuJ..2512830F. doi:10.1002/chem.201903120. PMC 7027550. PMID 31328293.
  5. ↑ Richard A. Andersen, Geoffrey Wilkinson (1979). "Bis[(Trimethylsilyl)Methyl] Magnesium". Inorg. Synth. 19: 262–265. doi:10.1002/9780470132500.ch61.
  6. 1 2 Houben-Weyl Methods of Organic Chemistry Vol. XIII/2a, 4th Edition Organometallic Compounds of Group II of the Periodic Table (except mercury) (in German), Georg Thieme Verlag, 2014, p. 215, ISBN 978-3-13-180654-3
  7. ↑ Jane E. Macintyre (1994), Dictionary of Organometallic Compounds (in German), CRC Press, p. 2273, ISBN 978-0-412-43060-2
  8. ↑ Weiss, E. (1964). "Die Kristallstruktur des Dimethylmagnesiums". J. Organomet. Chem. 2 (4): 314–321. doi:10.1016/S0022-328X(00)82217-2.
  9. ↑ Snow, A.I.; Rundle, R.E. (1951). "Structure of Dimethylberyllium". Acta Crystallographica. 4 (4): 348–52. Bibcode:1951AcCry...4..348S. doi:10.1107/S0365110X51001100. hdl:2027/mdp.39015095081207.
  10. ↑ Starowieyski, Kazimierz B.; Lewinski, Janusz; Wozniak, Robert; Lipkowski, Janusz; Chrost, Andrzej (2003). "Di- tert -butylmagnesium: Synthesis and Structure". Organometallics. 22 (12): 2458–2463. doi:10.1021/om030091j.