Silyl Azide Research Articles

Avenue to novel o-carboranyl boron compounds - reactivity study of o-carborane-fused aminoborirane towards organic azides.

Herein we report the reactivity study of o-carborane-fused bis(trimethylsilyl)aminoborirane towards three different types of organic azides, i.e., aryl, alkyl, and silyl azides. The reaction with ArN3 (Ar = 2,6-iPr2C6H4, 2,6-C6H3Cl2, 2,4,6-C6H2Br3, C6F5) resulted in the cycloaddition of ArN3 to the borirane BN unit accompanied by silyl migration. Conversely, in the reaction with BnN3, only the BnN3 : borirane 1 : 2 ring expansion product was obtained. Finally, the reaction with Me3SiN3 resulted in a formal nitrene insertion product under thermal conditions. All of the newly obtained o-carborane-fused BN-containing heterocycles were fully characterized, and the mechanism of these substituent-dependent reactions was studied using DFT calculations.

Isomerization of Silylnitrene to Silanimine: A Density Functional Study

Density functional theory is used to study the isomerization of closed- shell singlet and triplet silylnitrene to corresponding silanimine. Our calculation predicted that singlet silylnitrene is a first order saddle point and silylnitrene has a triplet ground state. The energy barrier of 79.0 Kcal mol-1 is predicted for the 1,2- hydrogen migration (i.e. isomerization) of triplet H3SiN → H2SiNH. It is also predicted that intermediate silylnitrene is not present during the direct photolysis of silyl azide for Curtius type rearrangement.

Stable Molecular Surface Modification of Nanostructured, Mesoporous Metal Oxide Photoanodes by Silane and Click Chemistry.

Binding functional molecules to nanostructured mesoporous metal oxide surfaces provides a way to derivatize metal oxide semiconductors for applications in dye-sensitized photoelectrosynthesis cells (DSPECs). The commonly used anchoring groups, phosphonates and carboxylates, are unstable as surface links to oxide surfaces at neutral and high pH, leading to rapid desorption of appended molecules. A synthetically versatile molecular attachment strategy based on initial surface modification with a silyl azide followed by click chemistry is described here. It has been used for the stable installation of surface-bound metal complexes. The resulting surfaces are highly stabilized toward complex loss with excellent thermal, photochemical, and electrochemical stabilities. The procedure involves binding 3-azidopropyltrimethoxysilane (APTMS) to nanostructured mesoporous TiO2 or tin-doped indium oxide (ITO) electrodes by silane attachment followed by azide-terminated, Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reactions with an alkyne-derivatized ruthenium(II) polypyridyl complex. The chromophore-modified electrodes display enhanced photochemical and electrochemical stabilities compared to phosphonate surface binding with extended photoelectrochemical oxidation of hydroquinone for more than ∼6 h with no significant decay.

Synthesis, structure and reactivity of a donor-stabilised silylene with a bulky bidentate benzamidinato ligand.

The novel donor-stabilised silylene was prepared in a four-step synthesis, starting from bis(2,6-diisopropylphenyl)carbodiimide (Dipp-N[double bond, length as m-dash]C[double bond, length as m-dash]N-Dipp), and its reactivity was studied in a series of oxidative addition reactions and a nucleophilic substitution reaction. The three-coordinate silicon(ii) complex contains the bulky bidentate amidinato ligand Dipp-NC(Ph)N-Dipp(-) and a dimethylamido ligand. Treatment of with N2O afforded the dinuclear five-coordinate silicon(iv) complex (SiO2N3 skeletons), and the reaction with S8 yielded the dinuclear four-coordinate silicon(iv) complex (SiS2N2 skeletons). Treatment of with Se and Te afforded the respective four-coordinate silicon(iv) complexes (SiSeN3 skeleton) and (SiTeN3 skeleton), which contain an Si[double bond, length as m-dash]Se and Si[double bond, length as m-dash]Te double bond, respectively. The reaction of with the silyl azide Me3SiN3 yielded the four-coordinate silicon(iv) complex (SiN4 skeleton) with an Si[double bond, length as m-dash]N double bond, whereas the reaction with the alkyl azide PhSCH2N3 gave the four-coordinate silicon(iv) complex (SiSN3 skeleton), the first silicon(iv) complex with an unsubstituted methyleneamido ligand. The reaction of with [Fe(CO)5] afforded the four-coordinate silicon(ii) complex (SiFeN3 skeleton) with an Si-Fe bond. Compounds (and the precursors and (five-coordinate silicon(iv) complexes with an SiCl3N2 and SiCl2N3 skeleton, respectively) in the synthesis of ) were characterised by elemental analyses, crystal structure analyses and multinuclear NMR spectroscopic studies in the solid state and in solution.

Das chlorsilylsubstituierte Silanimin tBu 2Si [dbnd]N [sbnd]SiCl tBu 2

In the thermolysis of the silaterazolines silatetrazoline t Bu 2Si N SiCl t Bu 2 · t Bu 3SiN 3 the silanimine t Bu 2Si N SiCl t Bu 2 and the silyl azide t Bu 3SiN 3 are formed quantitatively. The silanimine t Bu 2Si N SiCl t Bu 2 has been trapped with Et 3NHF, Me 3NHCl, water, 1-butene, 2,3-dimethyl-1,3-butadiene, isobutene, methylvinyl ether, and t Bu 2SiClN 3. The structure of the disiloxane ( t Bu 2SiCl–NH–Si t Bu 2) 2O and of the bis(di- tert-butylchlorsilyl)-substituted silatetrazoline t Bu 2Si N SiCl t Bu 2 · t Bu 2SiClN 3 has been determined by X-ray structure analysis.

The structures of the azido-, isocyanato- and isothiocyanato- derivatives of methane and silane and their derivatives. A comparison of ab initio with experimental results

The equilibrium structures of various conformers of the azides, isocyanates and isothiocyanates with general type Me 3− n H n W–NXY, together with a small number of their halogenated derivatives, have been determined by Möller–Plessett (MP2) calculations under standard triple zeta valence + polarisation basis set conditions. The structures are compared with each other, with previous and other theoretical studies including CCSD(T) results, and with experimental spectral and diffraction results. The MP2 and CCSD(T) results correlate strongly for a series of these molecules; thus the CCSD(T) bond lengths are larger by about 1.9%. The angles are little different, partly as a result of balancing effects; where some CNN and CNC angles are smaller in CCSD(T) by ∼2–3°, but some CCSD(T) dihedral angles HCNN and HCNC are larger. The MP2 results for the wider group correlate closely with microwave and infrared spectra, and with electron diffraction data. In contrast, the B3LYP method, with the same bases, whilst apparently giving reasonable structures, gives very poor rotation constants, as a result of poor CNC angle determination. The present results suggest that the spectra of ethyl isocyanate, silyl azide, trimethylsilyl azide, and silyl isocyanate require reinvestigation. This is part of a wider study where the central atom W is the series of Group 14 tetrahedral atoms up to Pb; in this study, the central atom W is C and Si, with XY either NN, CO or CS.

Darstellung und Thermolyse tert-butylsubstituierter Silatetrazoline – Erzeugung der Silanimine tBu2Si=N-SiXtBu2 (X = F, Cl, Br, tBu) Synthesis and Thermolysis of the tert-Butyl-Substituted Silatetrazolines – Formation of the Silanimines tBu2Si=N-SiXtBu2 (X = F, Cl, Br, tBu)

The silanimine tBu2Si=N-SitBu3 reacts with the silyl azides tBuMe2SiN3 or tBu2SiXN3 (X = H, Me, F, Cl, Br) to form the corresponding tert-butyl-substituted 1-tri-tert-butylsilyl-4-triorganosilyl- 5,5-di-tert-butylsilatetrazolines. The silatetrazolines with chloro-di-tert-butylsilyl and bromo-di-tert-butylsilyl substituents can also be synthesized by treating two equivalents of tBu2SiXN3 (X = Cl, Br) with the silanide tBu3SiNa. In the thermolysis of the silaterazolines the silanimines tBu2Si=N-SiXtBu2 (X = F, Cl, Br, tBu) and silyl azides are formed in a first-order process. The silanimines tBu2Si=N-SiXtBu2 (X= F, Cl, Br, tBu) have been trapped with acetone by en-reaction. The structure of (dimethyl-tert-butylsilyl)-substituted silatetrazoline has been determined by X-ray structure analysis.

Organoaluminum chemistry with low valent aluminum — recent developments

The chemistry of mono and divalent aluminum has progressed very significantly in the last decade. Many fascinating and unusual results and novel structures of products have been realized. The monomeric form of divalent aluminum does not exist but dimers are well known and characterized. Stable Al(I) derivatives in both monomeric and tetrameric forms have been synthesized and structurally characterized. A common feature in these compounds is the use of bulky organic substituents. The chemistry of some of these compounds has also been explored. The monomeric Al(I) derivative, [HC(MeCNAr) 2]Al, very recently synthesized, exhibits interesting addition and insertion reactions with alkyne, carbon dioxide and silyl azide at room temperature.

An ESR study on structures of a series of silylnitrenes

Structures of a series of silylnitrenes formed from silyl azides were investigated by means of ESR. γ-Irradiation and photo-illumination of all the silyl azides resulted in the formation of triplet states even for those having two or three Si–N 3 groups in a molecule. ESR spectra of the silylnitrenes exhibited a part of the fine structure at around 820 mT. All the silyl azides studied gave nearly identical D-values (ca. 1.5 cm −1 ) and much larger than those in phenylnitrenes. The results suggested that electron spins are localized in the nitrogen p-orbitals to a large extent and was interpreted in terms of a mono-silane linkage of nitrene, –Si–N:, i.e., interrupting spin delocalization.

Addukte der Ethene Me 2EC(SiMe 3) 2 (E=Si, Ge, Sn) mit LiR und RN 3: Wie rasch bilden sie sich?

Unsaturated compounds Me 2EC(SiMe 3) 2 (E=Si, Ge, Sn) are formed as short-lived intermediates by reaction of Me 2EXCBr(SiMe 3) 2 with LiR via Me 2EXCLi(SiMe 3) 2 (X=electronegative substituent; R=organyl) and — in the absence of trapping reagents — react with Me 2EXCLi(SiMe 3) 2 and LiR (as long as present) under formation of cyclobutanes [Me 2EC(SiMe 3) 2] 2 as well as adducts Me 2ERCLi(SiMe 3) 2 of Me 2EC(SiMe 3) 2 and LiR. In the presence of an excess of organyl or silyl azides RN 3, as well as lithium organyls or silyls LiR, which indeed act as very active trapping reagents for Me 2EC(SiMe 3) 2 with formation of [3+2] cycloadducts Me 2EC(SiMe 3) 2 ·RN 3 and adducts Me 2ERCLi(SiMe 3) 2, the formation of cyclobutanes and adducts is suppressed in the first case, whereas adducts are formed exclusively in the second case. As a result of determination of relative amounts of the products, formed by addition of Me 2SiBrCBr(SiMe 3) 2 to two different trapping reagents LiR and LiR′ or LiR and RN 3 in Et 2O, relative rates of the reactions of LiR or RN 3 with the silene Me 2SiC(SiMe 3) 2 are determined. Hereafter the insertion reactivity of LiR and the [3+2] cycloaddition reactivity of RN 3 decreases when the bulkiness of R increases (decreasing reactivity in the order LiMe>Li n Bu>LiPh>Li t Bu; LiMe>LiCH(SiMe 3) 2>LiC(SiMe 3) 3; Me 3SiN 3> t BuMe 2SiN 3> t Bu 2HSiN 3> t Bu 2MeSiN 3>Ph 3SiN 3> t Bu 3SiN 3). The influences of electronic effects are obviously smaller than those of steric effects (decreasing reactivity in the order LiC(SiClMe 2)(SiMe 3) 2>LiC(SiBrMe 2)(SiMe 3) 2>LiC(SiMe 3) 3; t Bu 2MeSiN 3> t Bu 2ClSiN 3; Me 3CN 3>Me 3SiN 3).

Polymer-supported silyl cyanide and silyl azide: Useful reagents for solid-phase applications

The support of a delicate reagent on a solid matrix allows for better and safer handling of the reagent itself. Because we had an interest in silicon-based supported reagents(1) we turned our attention to a polymer-supported trialkylsilyl cyanide and trialkylsilyl azide starting from a commercially available trialkylsilane resin. The supported cyanide was obtained with excellent yield and proved to be shelf-stable. This supported reagent was reacted with a series of aldehydes and ketones yielding the corresponding polymer-supported cyanohydrins in good-to-excellent yields. A stability study on a model cyanohydrin demonstrated that these supported intermediates also can be stored for a prolonged time. For the last step, a cleavage strategy that could release either cyanohydrins or alpha-hydroxy esters was adopted. Finally, we prepared a polymer-supported trialkylsilyl azide, which also proved to be shelf-stable.

Polymer-supported silyl cyanide and silyl azide: Useful reagents for solid-phase applications

The support of a delicate reagent on a solid matrix allows for better and safer handling of the reagent itself. Because we had an interest in silicon-based supported reagents1 we turned our attention to a polymer-supported trialkylsilyl cyanide and trialkylsilyl azide starting from a commercially available trialkylsilane resin. The supported cyanide was obtained with excellent yield and proved to be shelf-stable. This supported reagent was reacted with a series of aldehydes and ketones yielding the corresponding polymer-supported cyanohydrins in good-to-excellent yields. A stability study on a model cyanohydrin demonstrated that these supported intermediates also can be stored for a prolonged time. For the last step, a cleavage strategy that could release either cyanohydrins or α-hydroxy esters was adopted. Finally, we prepared a polymer-supported trialkylsilyl azide, which also proved to be shelf-stable. © 2000 John Wiley & Sons, Inc. Biotechnol Bioeng (Comb Chem) 71:38–43, 2000.

Mechanistic Studies of the Zirconium−Triisopropanolamine-Catalyzed Enantioselective Addition of Azide to Cyclohexene Oxide

The mechanism of the enantioselective ring-opening of cyclohexene oxide by Me3SiN3, catalyzed by zirconium complexes of the C3-symmetric ligand (+)-(S,S,S)-triisopropanolamine, has been investigated. Measurements of molecular weights of precatalyst species show that complexes are formed with average trimeric aggregation. Kinetics measurements reveal the overall process to be approximately half order in total zirconium, epoxide, and Me3SiN3 components. The reaction also shows a strong nonlinear relationship between enantiomeric excess of product azido ether vs the incorporation of (R,S,S)-triisopropanolamine ligand in the catalyst mixture. On the basis of these and other results, a preequilibrium interconversion of dimeric and tetrameric zirconium−triisopropanolamine species is proposed to occur rapidly with respect to the rate of epoxide ring-opening, with the dimeric form being the active catalyst. The reaction is accelerated by silyl ethers or by small amounts of water or alcohol, whereas larger amounts of protic additives inhibit the reaction. Enantioselectivity is eroded at catalyst concentrations less than 1 mole-percent and at high concentrations of cyclohexene oxide. Both enantioselectivity and rate are influenced to a small extent by the nature of the silyl azide employed for the first catalytic turnover, suggesting that a silyl fragment becomes irreversibly incorporated in the catalyst structure. It is proposed that catalytic activity requires the cooperative action of two zirconium centers for the binding and delivery of azide to epoxide.

Synthesis and Structure of a Novel Lewis Acid-Base Adduct, (H(3)C)(3)SiN(3).GaCl(3), en Route to Cl(2)GaN(3) and Its Derivatives: Inorganic Precursors to Heteroepitaxial GaN.

The formation of a novel Lewis acid-base complex between the silyl azide Si(CH(3))(3)N(3) and GaCl(3) having the formula (H(3)C)(3)SiN(3).GaCl(3)()()(1) is demonstrated. The X-ray crystal structure of 1 shows that the electron-donating site is the nitrogen atom directly bonded to the organometallic group. Compound 1 crystallizes in the orthorhombic space group Pnma, with cell dimensions a = 15.823(10) Å, b = 10.010(5) Å, c = 7.403(3) Å, and Z = 4. Low-temperature decomposition of 1 via loss of (H(3)C)(3)SiCl yields Cl(2)GaN(3) (2), which serves as the first totally inorganic (C,H-free) precursor to heteroepitaxial GaN by ultrahigh-vacuum chemical vapor deposition. A volatile monomeric Lewis acid-base adduct of 2 with trimethylamine, Cl(2)GaN(3).N(CH(3))(3) (3), has also been prepared and utilized to grow high-quality GaN on Si and basal plane sapphire substrates. The valence bond model is used to analyze bond lengths in organometallic azides and related adducts.

Synthesis and Reactivity of N-Phosphanyl Phosphazenes

Abstract The reaction of phosphorus (III) halides, R′3−n PXn (X [dbnd] F, C1), with silyl azides, R3SiN3, are described. N-silyated halo- phosphazenes, R'3−n PX [dbnd]N[sbnd]SiR3, are only obtained with fluorophosphanes having bulky substituents. Usually azidophosphanes, R'3−nP(N3)n, are formed as intermediates. These may react both as azide and as phosphane components in the Staudinger reaction forming N[sbnd]phosphany 1 phosphazenes, R'2P[sbnd]N[dbnd]PR3, or azidophosphazenes, R'3−nP(N3)n[dbnd]NY (n = 1, 2), which can be converted into di- and triphosphazenes, R' P(N[dbnd]PR3)n[dbnd]NY. A one pot procedure for preparing N[sbnd]phosphanyl phosphazenes had been developed. Replacement as well as ooxidation reactions of Cl2P[sbnd]N[dbnd]PPh3 and its derivatives are presented.

New synthetic routes towards polyphosphazenes

AbstractTwo new methods for the synthesis of polyphosphazenes are described. The first is based on the catalyzed polycondensation of phosphoranimines using various catalysts and initiators. Certain mechanistic aspects of this process with reactive intermediates are discussed. Linear polymers are formed quantitatively at temperatures around 100 °C in a few hours (the thermal process requires a few days at 200 °C). The second method is based on the direct reaction between phosphonites and phosphinites with silyl azides. This reaction proceeds by phosphine azide intermediates and provides new polyphosphazenes.

Hetero‐π‐Systeme, 17: Aminosilylen (Aminosilandiyl)

Hetero π‐Systems, 17. — Aminosilylen (Aminosilanediyl)Aminosilylene can be prepared by 254‐nm photolysis of silyl azide isolated in an argon matrix at 12 K. Subsequent irradiation with wavelengths > 300 nm yields silaisonitrile (3) and molecular hydrogen. This reaction may be reversed with 254‐nm light.

ChemInform Abstract: Efficient Synthesis of Silyl Azides Using Sodium Azide Impregnated on Amberlite XAD Resin.

ChemInformVolume 20, Issue 11 Organoelement Compounds ChemInform Abstract: Efficient Synthesis of Silyl Azides Using Sodium Azide Impregnated on Amberlite XAD Resin. K. SUKATA, K. SUKATA Nihon Tokushu Kagaku Kogyo Co., Ltd., Fukushima 970-04, JapanSearch for more papers by this author K. SUKATA, K. SUKATA Nihon Tokushu Kagaku Kogyo Co., Ltd., Fukushima 970-04, JapanSearch for more papers by this author First published: March 14, 1989 https://doi.org/10.1002/chin.198911226Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume20, Issue11March 14, 1989 RelatedInformation

Donoraddukte des Silanimins Me 2SiNSi tBu 3: Darstellung, Stabilität, Reaktivität

Silaneimine Me 2SiNSi tBu 3 ( 1), which is unstable under normal conditions with regard to dimerization, forms metastable adducts D · Me 2SiNSi tBu 3 ( 1 · D ≙ 3 with D = Et 2O, THF, NEt 3, NMe 2Et), which can be decomposed thermally to give 1 and D and, can thus serve as sources of 1. Adducts 1 · D result from Me 2SiXNLi(Si tBu 3) (X = halogen, amides formed by reaction of Me 2SiXNH-(Si tBu 3) with RLi) under LiX elimination in the presence of D and CF 3SO 3SiMe 3. Lewis basicity of D, relative to 1, increases in the order Et 2O < THF < NEt 3, Cl − < NMe 2Et < F −. Similarly resistance of 1 · D to decompose into the dimer of 1 and D also increases. Adducts 1 · D also decompose by action of excess donor, (viz. 1 · OEt 2 decomposes in Et 2O into ethylene and Me 2SiOEtNHSi tBu 3, 1 · NMe 2Et decomposes in NMe 2Et under Stevens migration into EtMeNCH 2Si-Me 2NHSi tBu 3). Reaction of adducts 1 · D with water, alcohols and amines, or with organic enes (propene, isobutene, dimethylbutadiene, cyclopentadiene), or with silyl azides (Me n tBu 3− n SiN 3), or with benzophenone, respectively, gives the OH and NH bond insertion products, or ene reaction products, or [2 + 3] cycloaducts, or a [2 + 2] cycloadduct of 1, respectively.

ChemInform Abstract: Unsaturated Silicon and Germanium Compounds. Part 23. Compounds of Silicon and Its Homologues. Part 75. Adduct Formation and Reactivity of Silane‐ and Germaneimines Me2E=NR (E: Si, Ge).

AbstractSilane‐ and germaneimines such as (II) are generated as reactive intermediates by thermal (2 + 3) cycloreversion from the (2 + 3) cycloadducts (I) or (III) of Me2E=C(SiMe3)2 or Me2E=NR1 with silyl azides.