Dimethylmagnesium

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Dimethylmagnesium
Me2Mg.png
Names
IUPAC name
Dimethylmagnesium
Identifiers
3D model (JSmol)
ChemSpider
PubChem CID
UNII
  • InChI=1S/2CH3.Mg/h2*1H3; X mark.svgN
    Key: KZLUHGRPVSRSHI-UHFFFAOYSA-N X mark.svgN
  • C[Mg]C
Properties
(CH3)2Mg
Molar mass 54.375 g·mol−1
AppearanceWhite solid
Density 0.96 g/cm3
Reacts
Related compounds
Related compounds
 Dibutylmagnesium
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 (C H 3)2 Mg . It is a white pyrophoric solid. [1] [2] Dimethylmagnesium is used in the synthesis of organometallic compounds.

Contents

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. [3]

Dimethylmagnesium can also be prepared by combining dimethylmercury and magnesium. [5] [6]

Calcium metal, magnesium metal and methyl iodide reacts in diethyl ether to produce dimethylmagnesium. [5]

Ca + Mg + 2 CH3I → CaI2 + (CH3)2Mg

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. [7]

The linear chain structure seen for dimethylmagnesium is also observed for diethylmagnesium and dimethylberyllium. [8] Di(tert-butyl)magnesium is however a dimer. [9]

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 Richard A. Andersen, Geoffrey Wilkinson (1979). "Bis[(Trimethylsilyl)Methyl] Magnesium". Inorganic Syntheses. Vol. 19. pp. 262–265. doi:10.1002/9780470132500.ch61. ISBN   978-0-471-04542-7.{{cite book}}: |journal= ignored (help)
  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. doi:10.1002/chem.201903120. PMC   7027550 . PMID   31328293.
  5. 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
  6. ↑ Jane E. Macintyre (1994), Dictionary of Organometallic Compounds (in German), CRC Press, p. 2273, ISBN   978-0-412-43060-2
  7. ↑ Weiss, E. (1964). "Die Kristallstruktur des Dimethylmagnesiums". J. Organomet. Chem. 2 (4): 314–321. doi:10.1016/S0022-328X(00)82217-2.
  8. ↑ 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 .
  9. ↑ 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.
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