Dimethylmagnesium

❧

Wikipedia

Dimethylmagnesium
Names
IUPAC name
Dimethylmagnesium
Identifiers
3D model (JSmol)
ChemSpider
UNII
  • InChI=1S/2CH3.Mg/h2*1H3; ☒N
    Key: KZLUHGRPVSRSHI-UHFFFAOYSA-N ☒N
  • 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).
☒N verify (what is checkY☒N ?)

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.

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]

The linear chain structure seen for dimethylmagnesium is also observed for diethylmagnesium and dimethylberyllium.[9] Di(tert-butyl)magnesium is however a dimer.[10]

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.