(Trimethylsilyl)methyllithium

Identifiers

CAS Number

* 1822-00-0

3D model (JSmol)

* Interactive image

ECHA InfoCard | 100.157.622
EC Number |

* 629-440-7

PubChem CID

* 3482579

CompTox Dashboard (EPA)

* DTXSID90392901

InChI

* InChI=1S/C4H11Si.Li/c1-5(2,3)4;/h1H2,2-4H3;/q-1;+1

Key: KVWLUDFGXDFFON-UHFFFAOYSA-N

SMILES

* [Li+].C[Si](C)(C)[CH2-]

Properties

Chemical formula

| C4H11LiSi
Molar mass | 94.16 g·mol−1
Appearance  | white or colorless solid
Density | 0.937 g/cm3
Hazards
GHS labelling:[1]

Pictograms

Signal word

| Danger

Hazard statements

| H225, H314

Precautionary statements

| P210, P233, P240, P241, P242, P243, P260, P264, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P363, P370+P378, P403+P235, P405, P501

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Infobox references

Chemical compound

(Trimethylsilyl)methyllithium is classified both as an organolithium compound and an organosilicon compound. It has the empirical formula LiCH2Si(CH3)3, often abbreviated LiCH2tms. It crystallizes as the hexagonal prismatic hexamer [LiCH2tms]6, akin to some polymorphs of methyllithium.[2] Many adducts have been characterized including the diethyl ether complexed cubane [Li4(μ3-CH2tms)4(Et2O)2][3] and [Li2(μ-CH2tms)2(tmeda)2].[4]

## Contents

* 1 Preparation
* 2 Use in methylenations
* 3 Metal derivatives
* 4 Related compounds
* 5 References

## Preparation[edit]

(Trimethylsilyl)methyllithium, which is commercially available as a THF solution, is usually prepared by treatment of [(trimethylsilyl)methyl chloride with butyllithium:[5]

(CH3)3SiCH2Cl + BuLi → (CH3)3SiCH2Li + BuCl

Trimethylsilylmethyl magnesium chloride is often functionally equivalent to trimethylsilylmethyllithium. It is prepared by the Grignard reaction of trimethylsilylmethyl chloride.[6][7]

## Use in methylenations[edit]

In one example of the Peterson olefination, (trimethylsilyl)methyllithium reacts with aldehydes and ketones to give the terminal alkene (R1 = Me, R2 & R3 = H):

## Metal derivatives[edit]

Structure of the organoscandium complex with two trimethylsilylmethyl ligands, (C5H5)Sc(CH2tms)2(thf) (tms = Si(CH3)3, thf = tetrahydrofuran).[8] Color scheme: O (red), Sc (blue), Si (orange).

Trimethylsilylmethyllithium is widely used in organotransition metal chemistry to affix trimethylsilylmethyl ligands. Such complexes are usually produced by salt metathesis involving metal chlorides. These compounds are often highly soluble in nonpolar organic solvents. These complexes enjoy stability because trimethylsilylmethyl ligands are bulky and they resist beta-hydride elimination. In these regards, trimethylsilylmethyl is akin to neopentyl.

## Related compounds[edit]

* bis(trimethylsilyl)methyllithium[9]
* tris(trimethylsilyl)methyllithium[10]

## References[edit]

1. ^ "(Trimethylsilyl)methyllithium". pubchem.ncbi.nlm.nih.gov. Retrieved 12 January 2022.
2. ^ Tecle', Berhan; Maqsudur Rahman, A.F.M.; Oliver, John P. (1986). "X-ray Crystal Structure of Trimethylsilylmethyllithium". Journal of Organometallic Chemistry. 317 (3): 267–275. doi:10.1016/0022-328X(86)80537-X.
3. ^ Tatic, Tanja; Meindl, Kathrin; Henn, Julian; Pandey, Sushil Kumar; Stalke, Dietmar (2010). "The First Asymmetric Organolithium Tetramers with Simple Ether Donor Bases". Chemical Communications. 46 (25): 4562–4564. doi:10.1039/c002504f. PMID 20502820.
4. ^ Tatic, Tanja; Ott, Holger; Stalke, Dietmar (2008). "Deaggregation of Trimethylsilylmethyllithium". European Journal of Inorganic Chemistry. 2008 (24): 3765–3768. doi:10.1002/ejic.200800610.
5. ^ Age, David J.; Werth, Jacob (2019). "Trimethylsilylmethyllithium". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rt321. ISBN 978-0471936237.
6. ^ Brennan, David J.; Graaskamp, James M.; Dunn, Beverly S.; Allcock, Harry R. (2007) [1989]. Organosilicon Derivatives of Cyclic and High Polymeric Phosphazenes. Inorganic Syntheses. pp. 60–68. doi:10.1002/9780470132562.ch15. ISBN 9780470132562.
7. ^ Shioiri, Takayuki; Aoyama, Toyohik; Mori, Shigehiro (1990). "Trimethylsilyldiazomethane". Organic Syntheses. 68: 1. doi:10.15227/orgsyn.068.0001.
8. ^ Li, Xiaofang; Nishiura, Masayoshi; Hu, Lihong; Mori, Kyouichi; Hou, Zhaomin (2009). "Alternating and Random Copolymerization of Isoprene and Ethylene Catalyzed by Cationic Half-Sandwich Scandium Alkyls". Journal of the American Chemical Society. 131 (38): 13870–13882. doi:10.1021/ja9056213. PMID 19728718.
9. ^ Jerry L. Atwood; Torgny Fjeldberg; Michael F. Lappert; N. Tuyet Luong-Thi; Riz Shakir; Andrew J. Thorne (1984). "Molecular structures of Bis(trimethylsilyl)methyl-lithium [(LiR), R = CH(SiMe3)2] in the Vapour (Gas-Phase Electron Diffraction: a Monomer, n= 1) and the Crystal (X-ray: a Polymer, n=∞)". Journal of the Chemical Society, Chemical Communications (17): 1163–1165. doi:10.1039/C39840001163.
10. ^ Colin Eaborn; Peter B. Hitchcock; J. David Smith; Alice C. Sullivan (1983). "Crystal structure of the Tetrahydrofuran Adduct of Tris(trimethylsilyl)-Methyl-Lithium, [Li(thf)4][Li{C(SiMe3)3}2], an Ate Derivative of Lithium". Journal of the Chemical Society, Chemical Communications: 827–828. doi:10.1039/C39830000827.

*[CID]: Compound ID
*[EPA]: U.S. Environmental Protection Agency
*[H225]: H225: Highly flammable liquid and vapour
*[H314]: H314: Causes severe skin burns and eye damage
*[P210]: P210: Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
*[P233]: P233: Keep container tightly closed.
*[P240]: P240: Ground and bond container and receiving equipment.
*[P241]: P241: Use explosion-proof electrical/ventilating/light/.../equipment.
*[P242]: P242: Use only non-sparking tools.
*[P243]: P243: Take action to prevent static discharges.
*[P260]: P260: Do not breathe dust/fume/gas/mist/vapours/spray.
*[P264]: P264: Wash ... thoroughly after handling.
*[P280]: P280: Wear protective gloves/protective clothing/eye protection/face protection.
*[P301+P330+P331]: P301+P330+P331: IF SWALLOWED: Rinse mouth. Do NOT induce vomiting.
*[P303+P361+P353]: P303+P361+P353: IF ON SKIN (or hair): Remove/Take off immediately all contaminated clothing. Rinse skin with water [or shower].
*[P304+P340]: P304+P340: IF INHALED: Remove victim to fresh air and keep at rest in a position comfortable for breathing.
*[P305+P351+P338]: P305+P351+P338: IF IN EYES: Rinse continuously with water for several minutes. Remove contact lenses if present and easy to do. Continue rinsing.
*[P310]: P310: Immediately call a POISON CENTER or doctor/physician.
*[P321]: P321: Specific treatment (see ... on this label).
*[P363]: P363: Wash contaminated clothing before reuse.
*[P370+P378]: P370+P378: In case of fire: Use ... to extinguish.
*[P403+P235]: P403+P235: Store in a well ventilated place. Keep cool.
*[P405]: P405: Store locked up.
*[P501]: P501: Dispose of contents/container to ...