Silyl Cyanide Research Articles

Gas-Phase Preparation of Silyl Cyanide (SiH3CN) via a Radical Substitution Mechanism.

The silyl cyanide (SiH3CN) molecule, the simplest representative of a fully saturated silacyanide, was prepared in the gas phase under single-collision conditions via a radical substitution mechanism. The chemical dynamics were direct and revealed a pronounced backward scattering as a consequence of a transition state with a pentacoordinated silicon atom and almost colinear geometry of the attacking cyano radical and leaving hydrogen. Compared to the isovalent cyano (CN)-methane (CH4) system, the CN-SiH4 system dramatically reduces the energy of the transition state to silyl cyanide by nearly 100 kJ mol-1, which reveals a profound effect on the chemical bonding and reaction mechanism. In extreme high-temperature environments including circumstellar envelopes of IRC +10216, this versatile radical substitution mechanism may synthesize organosilicon molecules via reactions of silane with doublet radicals. Overall, this study provides rare insights into the exotic reaction mechanisms of main-group XIV elements in extreme environments and affords deeper insights into fundamental molecular mass growth processes involving silicon in our universe.

Inelastic scattering of interstellar silyl cyanide (SiH3CN) by helium atoms : cross-sections and rate coefficients for A- and E-SiH3CN

ABSTRACT Rotational inelastic scattering of silyl cyanide (SiH3CN) molecule with helium (He) atoms is investigated. Three-dimensional potential energy surface (3D-PES) for the SiH3CN–He interacting system is carried out. The ab initio 3D-PES is computed using explicitly correlated coupled cluster approach with single, double, and perturbative triple excitation CCSD(T)-F12a connected to augmented-correlation consistent-polarized valence triple zeta Gaussian basis set. A global minimum at (R = 6.35 bohr; θ = 90○; ϕ = 60○) with a well depth of 52.99 cm−1 is pointed out. Inelastic rotational cross-sections are emphasized for the 22 first rotational levels for total energy up to 500 cm−1 via close coupling (CC) approach in the case of A-SiH3CN and for the 24 first rotational levels for total energy up to 100 cm−1 via CC and from 100 to 500 cm−1 via coupled states (CS) in the case of E-SiH3CN. Rate coefficients are derived for temperature until 80 K for both A- and E-SiH3CN–He systems. Propensity rules are obtained for |ΔJ| = 2 processes with broken parity for A-SiH3CN and for |ΔJ| = 2 processes with |ΔK| = 0 and unbroken parity for E-SiH3CN.

Regio- and Stereoselective Carboindation of Internal Alkynyl Ethers with Organosilicon or -stannane Nucleophiles.

We achieved regio- and stereoselective carboindation of terminal and internal alkynyl ethers using InI3 and organosilicon or -stannane nucleophiles to synthesize (Z)-β-alkoxyalkenylindiums. The carbometalation regio- and stereoselectively proceeded in anti-addition fashion, which was confirmed by X-ray diffraction analysis of (Z)-β-alkoxyalkenylindium products. Theoretical calculation on the carboindation of alkynyl ethers to elucidate the effect of an alkoxy group was conducted in parallel with calculations on a carbon analogue of the alkynyl ether. Reaction profiles and computational data of carboindation suggest that the alkoxy group enhances the interaction between InI3 and an alkyne moiety and reduces the activation energy. Many types of carbon nucleophiles such as silyl ketene acetals, silyl ketene imines, a silyl cyanide, an alkynyl stannane, and an allylic stannane were applicable to the present reaction system to give highly functionalized metalated enol ethers (β-alkoxyalkenylindiums). The prepared β-alkoxyalkenylindiums were transformed to various functionalized tetrasubstituted enol ethers by iodination followed by Suzuki coupling. The synthesis of a seven-membered ring compound containing a phenol ether moiety was accomplished using a sequential process that included the present stereoselective carboindation.

Laboratory Rotational Spectra of Silyl Isocyanide

Abstract The rotational spectrum of silyl isocyanide (SiH3NC), an isomer of the well-studied silyl cyanide (SiH3CN), has been detected in the laboratory in a supersonic molecular beam, and the identification was confirmed by observations of the corresponding rotational transitions in the rare isotopic species and SiH3N13C. Spectroscopic constants derived from 19 transitions between 11 and 35 GHz in the three lowest harmonically related rotational transitions in the K = 0 and 1 ladders of the normal isotopic species including the nitrogen nuclear quadrupole hyperfine constant allow the principal astronomical transitions of SiH3NC to be calculated to an uncertainty of about 4 km s−1 in equivalent radial velocity, or within the FWHM of narrow spectral features in the inner region of IRC+10216 near 200 GHz. The concentration of SiH3NC in our molecular beam is three times less than SiH3CN, or about the same as the corresponding ratio of the isomeric pair SiNC and SiCN produced under similar conditions. Silyl isocyanide is an excellent candidate for astronomical detection, because the spectroscopic and chemical properties are very similar to SiH3CN, which was recently identified in the circumstellar envelope of IRC+10216 by Cernicharo et al. and of SiNC and SiCN in the same source.

Discovery of methyl silane and confirmation of silyl cyanide in IRC +10216.

We report the discovery in space of methyl silane, CH3SiH3, from observations of ten rotational transitions between 80 and 350 GHz (Ju from 4 to 16) with the IRAM 30 m radio telescope. The molecule was observed in the envelope of the C-star IRC +10216. The observed profiles and our models for the expected emission of methyl silane suggest that the it is formed in the inner zones of the circumstellar envelope, 1-40 R*, with an abundance of (0.5-1) × 10-8 relative to H2. We also observed several rotational transitions of silyl cyanide (SiH3CN), confirming its presence in IRC +10216 in particular, and in space in general. Our models indicate that silyl cyanide is also formed in the inner regions of the envelope, around 20 R*, with an abundance relative to H2 of 6×10-10. The possible formation mechanisms of both species are discussed. We also searched for related chemical species but only upper limits could be obtained.

Synthesis of 2-Cyano-3-Nitroporphyrin Derivatives with Silyl Cyanide

2-Cyano-3-nitroporphyrin derivatives were synthesised by the reaction of 2-nitroporphyrin with trimethylsilyl cyanide in the presence of tetrabutylammonium fluoride with moderate yields. The reaction took place regioselectively on the 3-position carbon of the porphyrins, which was confirmed by X-ray analysis.

Synthesis of 3-cyano-N-confused porphyrin derivatives by silyl cyanide

3-Cyano- N-confused porphyrin derivatives were synthesised by the reaction of N-confused porphyrin with trimethylsilyl cyanide in the presence of tetrabutylammonium fluoride in moderate yield. The reaction took placed regioselectively in the 3-position carbon of the inverted pyrrole of N-confused porphyrins.

ChemInform Abstract: A Reaction of 1,2‐Diamines and Aldehydes with Silyl Cyanide as Cyanide Pronucleophile to Access 2‐Aminopyrazines and 2‐Aminoquinoxalines.

AbstractThe reaction proceeds through a tandem sequence of desilylation followed by Strecker reaction, amide‐forming cyclization and dehydrogenative aromatization.

A reaction of 1,2-diamines and aldehydes with silyl cyanide as cyanide pronucleophile to access 2-aminopyrazines and 2-aminoquinoxalines

A new reaction of 1,2-diamines and aldehydes with TMSCN affords an efficient and diversity-feasible entry to 2-aminopyrazines and 2-aminoquinoxalines.

ChemInform Abstract: Efficient Syntheses of Substituted (.+‐.)‐3‐Oxoisoindoline‐1‐carbonitriles and Carboxamides Using OSU‐6.

AbstractThe Strecker‐type reaction of o‐formylbenzoic acid (I) with silyl cyanide (III) and benzylic or aliphatic amines catalyzed by OSU‐6, an MCM‐41 type hexagonal mesoporous silica, can be tuned to generate two different products: substituted 3‐oxoisoindoline‐1‐carbonitriles (IV) at 23°C or the corresponding carboxamides (VI) at 78°C.

ChemInform Abstract: Straightforward Synthesis of 1,2‐Dicyanoalkanes from Nitroalkenes and Silyl Cyanide Mediated by Tetrabutylammonium Fluoride.

AbstractA straightforward synthesis of 1,2‐dicyanoalkanes by reacting nitroalkenes with trimethylsilyl cyanide in the presence of tetrabutylammonium fluoride is described.

ChemInform Abstract: Gallium Trihalide Catalyzed Sequential Addition of Two Different Carbon Nucleophiles to Esters by Using Silyl Cyanide and Ketene Silyl Acetals.

AbstractThe described method is applicable to aromatic, aliphatic and formic acid esters, and lactones as substrates giving the products with low to high yields.

Straightforward synthesis of 1,2-dicyanoalkanes from nitroalkenes and silyl cyanide mediated by tetrabutylammonium fluoride.

A straightforward synthesis of 1,2-dicyanoalkanes by reacting nitroalkenes with trimethylsilyl cyanide in the presence of tetrabutylammonium fluoride is described. The reaction proceeds through a tandem double Michael addition under mild conditions. Employing the hypervalent silicate generated from trimethylsilyl cyanide and tetrabutylammonium fluoride is essential for achieving this transformation. Mechanistic studies suggest that a small amount of water included in the reaction media plays a key role. This protocol is applicable to various types of substrates including electron-rich and electron-deficient aromatic nitroalkenes, and aliphatic nitroalkenes. Moreover, vinyl sulfones were found to be good alternatives, particularly for electron-deficient nitroalkenes. The broad substrate scope and functional group tolerance of the reaction makes this approach a practical method for the synthesis of valuable 1,2-dicyanoalkanes.

Gallium trihalide catalyzed sequential addition of two different carbon nucleophiles to esters by using silyl cyanide and ketene silyl acetals.

A sequential addition of silyl cyanide and ketene silyl acetals to esters was achieved by a gallium trihalide catalyst to produce β-cyano-β-siloxy esters. This is the first example of the sequential addition of two different carbon nucleophiles to esters. The employment of lactones provided α,α-disubstituted cyclic ethers with a cyano group and an ester moiety. A variety of esters and lactones are applicable to this reaction system.

ChemInform Abstract: Si—CN Bond Cleavage of Silyl Cyanides by an Iron Catalyst. A New Route of Silyl Cyanide Formation

AbstractReview: 37 refs.

ChemInform Abstract: Indium Triiodide Catalyzed Reductive Functionalization of Amides via the Single‐Stage Treatment of Hydrosilanes and Organosilicon Nucleophiles.

The indium triiodide catalyzed single-stage cascade reaction of N-sulfonyl amides with hydrosilanes and two types of organosilicon nucleophiles such as silyl cyanide and silyl enolates selectively promoted deoxygenative functionalization to give α-cyanoamines and β-aminocarbonyl compounds, respectively.

Si–CN Bond Cleavage of Silyl Cyanides by an Iron Catalyst. A New Route of Silyl Cyanide Formation

Abstract The reaction of silyl cyanide (R3SiCN) with hydrosilane (R′3SiH) in the presence of a catalytic amount of [(η5-C5H5)Fe(CO)2Me] formed R′3SiCN and R3SiH. This reaction involves Si–CN bond cleavage and provides a new method for the preparation of silyl cyanides. DFT calculation showed that coordinatively unsaturated [(η5-C5H5)Fe(CO)(SiMe3)] reacts exothermically with Me3SiCN to give the CN π-coordinated complex, [(η5-C5H5)Fe(CO)(η2-Me3SiCN)(SiMe3)], followed by exothermic silyl migration from the iron to the nitrogen atom of the η2-coordinated Me3SiCN with the activation energy of 8.8 kcal mol−1 to give [(η5-C5H5)Fe(CO)(Me3SiC=NSiMe3-κC,κN)]. The complex is one of the intermediates in the catalytic cycle. The related complex [(η5-C5Me5)Fe(CO)(κ-C,N-t-BuMe2SiC=NSiPh3)] was isolated in the reaction of [(η5-C5Me5)Fe(CO)(py)(SiPh3)] with t-BuMe2SiCN and characterized by 1H, 13C, and 29Si NMR spectroscopy. The activation energy of the Si–CN bond cleavage in [(η5-C5H5)Fe(CO)(κ-C,N-Me3SiC=NSiMe3)] was evaluated by DFT calculation to be 33.7 kcal mol−1 which is comparable to that in the reaction of acetonitrile (32.9 kcal mol−1).

Syntheses of Aldol Products and Cyanohydrins from Carboxylic Acids Using Hydrosilanes, Organosilicon Reagents, and Indium Triiodide Catalyst

Abstract Carboxylic acids were applied to an indium triiodide-catalyzed reductive aldol reaction and a reductive cyanation in order to produce aldol adducts and cyanohydrins, respectively, in which the separate addition of two kinds of hydrosilanes was crucial in combination with either ketene silyl acetals or silyl cyanides.

Indium Triiodide Catalyzed Reductive Functionalization of Amides via the Single-Stage Treatment of Hydrosilanes and Organosilicon Nucleophiles

The indium triiodide catalyzed single-stage cascade reaction of N-sulfonyl amides with hydrosilanes and two types of organosilicon nucleophiles such as silyl cyanide and silyl enolates selectively promoted deoxygenative functionalization to give α-cyanoamines and β-aminocarbonyl compounds, respectively.

ChemInform Abstract: The Carbon—Ferrier Rearrangement: An Approach Towards the Synthesis of C‐Glycosides

AbstractReview: 70 refs.