Tris(trimethylsilyl)amine
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Preferred IUPAC name
1,1,1-Trimethyl-N,N-bis(trimethylsilyl)silanamine | |
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3D model (JSmol)
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ChemSpider | |
ECHA InfoCard | 100.014.951 ![]() |
EC Number |
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PubChem CID
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CompTox Dashboard (EPA)
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Properties | |
C9H27NSi3 | |
Molar mass | 233.57g/mol |
Appearance | Waxy solid |
Melting point | 67–69ºC |
Boiling point | 215ºC (85ºC at 13mmHg) |
Solubility | Nonpolar organic solvents |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
Infobox references | |
Tris(trimethylsilyl)amine is the simplest tris(trialkylsilyl)amine which are having the general formula (R3Si)3N, in which all three hydrogen atoms of the ammonia are replaced by trimethylsilyl groups (-Si(CH3)3).[1] Tris(trimethylsilyl)amine has been for years in the center of scientific interest as a stable intermediate in chemical nitrogen fixation (i. e. the conversion of atmospheric nitrogen N2 into organic substrates under normal conditions).[2][3][4]
Production[]
Early attempts to prepare tris(trimethylsilyl)amine from ammonia and trimethylchlorosilane (TMS-Cl) were unsuccessful even at temperatures of 500 °C and in the presence of the base pyridine.[5][6] The reaction of ammonia and trimethylchlorosilane stops at the stage of the doubly silylated product bis(dimethylsilyl)amine (usually referred to as hexamethyldisilazane, HMDS).
![Synthese von Hexamethyldisilazan (HMDS)](http://upload.wikimedia.org/wikipedia/commons/thumb/a/a1/HMDS-Synthese.svg/250px-HMDS-Synthese.svg.png)
Tris(trimethylsilyl)amine is obtained by reaction of the sodium salt of hexamethyldisilazane - from hexamethyldisilazane and sodium amide[7] or from hexamethyldisilazane, sodium and styrene[1] - with trimethylchlorosilane in 80% yield.[8]
The lithium salt of hexamethyldisilazane - from hexamethyldisilazane and butyllithium[9] or from hexamethyldisilazane and phenyllithium[8] - reacts with trimethylchlorosilane only in yields of 50-60% to tris(trimethylsilyl)amine.
The reaction of lithium nitride with trimethylchlorosilane can be carried out as a one-pot reaction in THF with 72% yield.[10]
Properties[]
Tris(trimethylsilyl)amine is a colorless, crystalline[11][12] or waxy[7] solid which is stable to water and bases.[13] Alcohols or acids though cleave the Si-N-bond under formation of ammonia.[7]
Applications[]
Tris(trimethylsilyl)amine as a synthetic building block[]
From antimony trichloride and tris(trimethylsilyl)amine, a nitridoantimone cubane-type cluster can be formed almost quantitatively at –60 °C.[14]
Ketones can be trifluoromethylated in the presence of P4-t-Bu and nonamethyltrisilazane under mild conditions in yields of up to 84% with the inert fluoroform (HCF3, HFC-23).[15]
The monomer trichloro(trimethylsilyl)-phosphoranimine Cl3P=NSiMe3 is formed from tris(trimethylsilyl)amine and phosphorus pentachloride in hexane at 0 °C,
![Synthese von Trichlor(trimethylsilyl)phosphoranimin](http://upload.wikimedia.org/wikipedia/commons/thumb/2/2a/Synthese_von_Trichlor%28trimethylsilyl%29phosphoranimin.svg/400px-Synthese_von_Trichlor%28trimethylsilyl%29phosphoranimin.svg.png)
which can be polymerized to linear polydichlorophosphazenes with defined molecular weights and polydispersities.[16]
The cyclic trimer (NPCl2)3 hexachlorocyclotriphosphane is predominantly formed from tris(trimethylsilyl)amine and phosphorus pentachloride in boiling dichloromethane (about 40 °C) among other oligomers which gives upon heating over 250 °C high molecular weight, little defined polydichlorophosphazenes.
![Synthese von Hexachlorcyclotriphosphan](http://upload.wikimedia.org/wikipedia/commons/thumb/d/d0/Synthese_von_Hexachlorcyclotriphosphan.svg/400px-Synthese_von_Hexachlorcyclotriphosphan.svg.png)
Nitrogen trifluoride NF3 (which is used, inter alia, for the plasma etching of silicon wafers) is obtainable from tris(trimethylsilyl)amine and fluorine at –40 °C in acetonitrile, suppressing the formation of nitrogen and tetrafluorohydrazine, which are produced as undesirable by-products during the standard synthesis of nitrogen trifluoride from ammonia or ammonium fluoride.[17]
![Synthese von NF3](http://upload.wikimedia.org/wikipedia/commons/thumb/e/e7/Bildung_von_Stickstofftrifluorid.svg/450px-Bildung_von_Stickstofftrifluorid.svg.png)
Tris(trimethylsilyl)amine intermediate in chemical nitrogen fixation[]
The technical nitrogen fixation was made possible by the Haber-Bosch process, in which nitrogen is converted into ammonia by reductive protonation in the presence of iron catalysts under high pressures (> 150 bar) and temperatures (> 400 °C). In chemical nitrogen fixation (i.e., the transformation of atmospheric nitrogen under normal conditions into reactive starting materials for chemical syntheses, usually also ammonia), tris(trimethylsilyl)amine plays an important role in the so-called reductive silylation, since it is hydrolyzed with water to ammonia.
As early as 1895 it was observed that metallic lithium reacts with nitrogen to lithium nitride at room temperature.[18] In 1972, K. Shiina observed that lithium (as an electron donor) forms with trimethylsilyl chloride under darkening tris(trimethylsilyl)amine in the presence of chromium(III) chloride as a catalyst at room temperature with the nitrogen used for inerting.[2]
More recently, for the reductive silylation of N2, sodium has been used instead of lithium as the electron donor and molybdenum[19] and iron compounds[3] (such as pentacarbonyl iron or ferrocenes[20]) as catalysts, up to 34 equivalents of N(Me3Si)3 could be obtained per iron atom in the catalyst.
With a molybdenum-ferrocene complex as catalyst, a turnover number of up to 226 could be achieved.[21]
The catalytic productivity of the catalysts for chemical nitrogen fixation developed so far is, despite intensive research,[22] still by magnitude smaller than, for example, the modern polymerization catalysts of the metallocene type or enzymes.
References[]
- ^ Jump up to: a b J. Goubeau, J. Jiminéz-Barberá (1960), "Tris-(trimethylsilyl)-amin", ZAAC (in German), 303 (5–6), pp. 217–226, doi:10.1002/zaac.19603030502
- ^ Jump up to: a b K. Shiina (1972), "Reductive silylation of molecular nitrogen via fixation to tris(trimethylsilyl)amine", J. Am. Chem. Soc., 94 (26), pp. 9266–9267, doi:10.1021/ja00781a068
- ^ Jump up to: a b K.C. MacLeod, P.L. Holland (2013), "Recent developments in the homogeneous reduction of dinitrogen by molybdenum and iron", Nature Chemistry, 5, pp. 559–565, doi:10.1038/nchem.1620, PMC 3868624, PMID 23787744
- ^ W.I. Dzik (2016), "Silylation of dinitrogen catalyzed by hydridodinitrogen(triphenylphosphine) cobalt (I)", Inorganics, 4 (3), p. 21, doi:10.3390/inorganics4030021
- ^ R.O. Sauer (1944), "Derivatives of the methylchlorosilanes. I. Trimethylsilanol and its simple ethers", J. Am. Chem. Soc., 66 (10), pp. 1707–1710, doi:10.1021/ja01238a030
- ^ R.O. Sauer, R.H. Hasek (1946), "Derivatives of the methylchlorosilanes. IV. Amines", J. Am. Chem. Soc., 68 (2), pp. 241–244, doi:10.1021/ja01206a028
- ^ Jump up to: a b c C.R. Krüger, H. Niederprüm, M. Schmidt, O. Scherer (1966), H.F. Holtzlow (ed.), Sodium Bis(trimethylsilyl)amide and Tris(trimethylsilyl)amine, in Inorganic Syntheses, 8, Hoboken, NJ, USA: John Wiley & Sons, Inc., pp. 15–19, doi:10.1002/9780470132395.ch5, ISBN 9780470131671CS1 maint: multiple names: authors list (link)
- ^ Jump up to: a b U. Wannagat, H. Niederprüm (1961), "Beiträge zur Chemie der Silicium-Stickstoff-Verbindungen, XIII. Silylsubstituierte Alkaliamide", Chem. Ber. (in German), 94 (6), pp. 1540–1547, doi:10.1002/cber.19610940618
- ^ E.H. Amonoo-Neizer, R.A. Shaw, D.O. Skovlin, B.C. Smith, J.W. Rosenthal, W.L. Jolly (1966), H.F. Holtzlow (ed.), Lithium Bis(trimethylsilyl)amide and Tris(trimethylsilyl)amine, in Inorganic Syntheses, 8, Hoboken, NJ, USA: John Wiley & Sons, Inc., pp. 19–22, doi:10.1002/9780470132395.ch5, ISBN 9780470131671CS1 maint: multiple names: authors list (link)
- ^ W.L. Lehn (1964), "Preparation of tris(trimethylsilyl)- and tris(trimethylstannyl)amines", J. Am. Chem. Soc., 86 (2), p. 305, doi:10.1021/ja01056a057
- ^ Sigma-Aldrich Co., product no. {{{id}}}.
- ^ Nonamethyltrisilazane at AlfaAesar, accessed on 28. Dezember 2016 (PDF) (JavaScript required).
- ^ U. Wannagat, H. Niederprüm (1961), "dreifach silylierte Amine", ZAAC (in German), 308 (1–6), pp. 337–351, doi:10.1002/zaac.19613080135
- ^ M. Rhiel, F. Weller, J. Pebler, K. Dehnicke (1994), "[SbN(SbCl)3(NSbCl2)(NSiMe3)3·SbCl3], ein ungewöhnlicher Nitridoantimonkomplex mit Heterocubanstruktur", Angew. Chem. (in German), 106 (5), pp. 599–600, doi:10.1002/ange.19941060519CS1 maint: multiple names: authors list (link)
- ^ S. Okusu, K. Hirano, E. Tokunaga, N. Shibata (2015), "Organocatalyzed trifluormethylation of ketones and sulfonyl fluorides by fluoroform under a superbase system", ChemistryOpen, 4, pp. 581–585, doi:10.1002/open.201500160, PMC 4608523, PMID 26491635CS1 maint: multiple names: authors list (link)
- ^ US 5698664, "Synthesis of polyphosphazenes with controlled molecular weight and polydispersity"
- ^ US 8163262, "Method for production of nitrogen fluoride from trimethylsilylamines"
- ^ H. Deslandres (1895), "Absorption de l'azote par le lithium à froid", Comptes rendus, 121, pp. 886–887
- ^ Q. Liao, N. Saffon-Merceron, N. Mézailles (2015), "N2 reduction into silylamine at tridentate phosphine/Mo center: catalysis and mechanistic study", ACS Catal., 5 (11), pp. 6902–6906, doi:10.1021/acscatal.5b01626CS1 maint: multiple names: authors list (link)
- ^ M. Yuki, H. Tanaka, K. Sasaki, Y. Miyake, K. Yoshizawa, Y. Nishibayashi (2012), "Iron-catalyzed transformation of molecular dinitrogen into silylamine under ambient conditions", Nature Communications, 3, p. 1254, doi:10.1038/ncomms2264CS1 maint: multiple names: authors list (link)
- ^ H. Tanaka; et al. (2011), "Molybdenum-Catalyzed Transformation of Molecular Dinitrogen into Silylamine: Experimental and DFT Study on the Remarkable Role of Ferrocenyldiphosphine Ligands", J. Am. Chem. Soc., 133 (10), pp. 3498–3506, doi:10.1021/ja109181n
- ^ Y. Nishibayashi (2015), "Recent progress in transition-metal-catalyzed reduction of molecular dinitrogen under ambient reaction conditions", Inorg. Chem., 54 (19), pp. 9234–9247, doi:10.1021/acs.inorgchem.5b00881
- Nitrogen(−III) compounds
- Trimethylsilyl compounds