Trimethylsilane Research Articles

Features of determination of thickness of dielectric films obtained in searching experiments

The approach to determination of the thickness and the refractive indices of dielectric films obtained in searching experiments is discussed. Experiments of this kind often exhibit unpredictable values of thickness and refractive indices of films. Nondestructive noncontact methods of spectrophotometry and ellipsometry not involving preliminary preparation of samples are applied. The approach to determination of the thickness and the refractive indices of films is illustrated by means of samples of silicon carbonitride films obtained on silicon substrates by plasma-chemical decomposition of gas-phase trimethyl(phenylamino)silane.

ChemInform Abstract: Enantiopure Tertiary Trifluoromethyl Carbinols. Diastereoselective Approach Using Trifluoromethyl(trimethyl)silane

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Efficient formal synthesis of (±)-axamide-1 and (±)-axisonitrile-1 via an intramolecular Hosomi–Sakurai reaction

Efficient synthetic route to (±)-axamide-1 and (±)-axisonitrile-1 was established via an intramolecular Hosomi–Sakurai reaction of the corresponding allylsilane derivative, in very short steps. A formal synthesis of (±)-axamide-1 and (±)-axisonitrile-1 was achieved by using an intramolecular Hosomi–Sakurai reaction of the allylsilane derivative, as a key step, in which [(3-but-3-en-1-yl-3-methylcyclohex-1-en-1-yl)methyl](trimethyl)silane was transformed to a bicyclic compound possessing a core carbon framework under the oxidative dihydroxylation reaction conditions, in one step.

Novel Precursor for Development of Si–C2H4–Si Networks in SiCH for Application as a Low-k Cap Layer beyond 22 nm Nodes

SiCH films are a potentially very useful low-k cap layer for covering Cu trenches in ultralarge-scale integration (ULSI) devices. To induce Si–C2H4–Si networks in SiCH film structures, 1,1-divinyl silacyclopentane (DVScP) and 5-silaspiro-[4,4]-nonane (SSN) were designed and prepared. Isobutyl trimethyl silane (iBTMS) and diisobutyl dimethyl silane (DiBDMS) were also designed to form Si–CH2–Si networks in the SiCH molecular structure. SiCH films were formed by plasma-enhanced chemical vapor deposition (PECVD), for use as a low-k cap layer and a Cu diffusion barrier on top of the Cu trenches. We demonstrated additional Si–C2H4–Si networks that can effectively suppress Cu diffusion in SiCH low-k barrier films with a reduced k-value of 3.1.

Hydrolysis of Pesticides in Wastewater Catalyzed by Cu(II) Complexes of Silyl Based Cationic Micelles

The effect of cationic surfactant micelles, namely hexadecyl trimethyl silane ammonium chloride (A), dodecyl trimethyl silane ammonium chloride, (B) and their copper (II) ion complexes on the hydrolysis of the pesticides: diazinon, cypermethrin, and carbaryl was studied. The rate of the pesticides decay in water was significantly accelerated in presence of these cationic micellar solutions. Furthermore, the copper (II) ion complexes of these micellar were found to be much more effective in hydrolysis of these pesticides. The results indicate that the complexes with a 1:1 ratio of both ligands to the metal ions are the active species in catalytic hydrolysis of carbaryl pesticide. Kinetic study is explained.

Benzoyl peroxide (BPO)-promoted oxidative trifluoromethylation of tertiary amines with trimethyl(trifluoromethyl)silane

The benzoyl peroxide (BPO)-promoted oxidative functionalization of tertiary amines under transition-metal-free reaction conditions was developed. Various 1-trifluoromethylated tetrahydroisoquinoline derivatives were prepared by employing this method. It constitutes the first example of direct trifluoromethylation of tertiary amines.

Cobalt-catalyzed regio- and stereoselective intermolecular enyne coupling: an efficient route to 1,3-diene derivatives

The reaction of alkynes with vinyl arenes or vinyl trimethyl silane in the presence of a cobalt(II) complex, Zn and ZnI(2) in CH(2)Cl(2) at rt to 50 degrees C provides 1,3-dienes in good to excellent yields.

ChemInform Abstract: Catalytic Enantioselective Trifluoromethylation of Azomethine Imines with Trimethyl(trifluoromethyl)silane.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

O-Benzenedisulfonimide as a Reusable Brønsted Acid Catalyst for Hosomi-Sakurai Reactions

Various acetals or alcohols react with allyl(trimethyl)silane or 1-phenyl-2-(trimethylsilyl)acetylene in the presence of a catalytic amount of the Brønsted acid o-benzenedisulfonimide under mild conditions to give good yields of the corresponding products. The catalyst can be easily recovered and purified for use in further reactions, which has economic and ecological advantages.

A study on surface endothelialization of plasma coated intravascular stents

Abstract In this study, plasma nanocoatings with thickness of less than 50 nm were deposited onto two types of intravascular stents made of nitinol (NiTi alloy) and stainless steel from gas mixtures of trimethylsilane (TMS) and oxygen (O 2 ) in a direct current (DC) plasma reactor system. The surface properties, surface morphology, and surface chemistry of the plasma coated stents were characterized using surface contact angle measurements, scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS). In order to investigate their surface endothelialization effects, plasma coated stents were seeded with human umbilical vein endothelial cells (HUVECs) for cell culture study. The cell culture data showed that plasma nanocoatings deposited from a gas mixture of TMS:O 2 = 1:3 gave rise to a statistically significant increase in adhered cell numbers, which were 79.75 ± 6.18 on nitinol stents vs. 41.25 ± 9.38 cells on uncoated bare controls and 119.50 ± 12.40 on stainless stents vs. 56.85 ± 12.53 cells on uncoated bare controls. These results evidently demonstrated that plasma nanocoatings prepared from appropriate plasma chemistry or gas composition could significantly enhance the surface endothelialization on both nitinol stents and stainless steel intravascular stents.

Stereocontrolled Generation of the (2R) Chroman Core of Vitamin E: Total Synthesis of (2R,4′RS,8′RS)-α-Tocopherol

(2R,4'RS,8'RS)-alpha-tocopherol (1) was prepared using, as the two key steps, a novel diastereoselective TiCl(4)-promoted (S)-sulfoxide-directed allylation of ketal 2 with allyl trimethyl silane 3 to efficiently generate the challenging (2R) stereocenter of the chroman moiety and a cross-metathesis reaction with olefin 4 to efficiently join the lipophilic alkyl chain present in the final target.

Catalytic Enantioselective Trifluoromethylation of Azomethine Imines with Trimethyl(trifluoromethyl)silane

Ein Kinderspiel! Die Titelreaktion mit Azomethiniminen 1 nutzt ein einfach durchzuführendes Verfahren, das auf der Kombination eines China-Alkaloid-Bromsalzes 3 mit KOH beruht. Das Verfahren ist verlässlich und allgemein anwendbar. Trifluormethylsubstituierte Amine werden durch zweistufiges Entschützen des Produkts (S)-2 zugänglich.

Catalytic Enantioselective Trifluoromethylation of Azomethine Imines with Trimethyl(trifluoromethyl)silane

It′s a cinch! The title reaction with azomethine imines 1 uses an operationally simple procedure, based on the combination of the bromide salt of cinchona alkaloids (3) and KOH. The procedure is reliable and general. Trifluoromethyl-substituted amines can be accessed by a two-step deprotection of the product (S)-2.

Synthesis and reactions of pyrazole-4-carbaldehydes

1-, 3-, and 5-Alkylpyrazoles, as well as linearly bridged bis-pyrazoles, were converted into the corresponding 4-formyl derivatives by Vilsmeier-Haak reaction both under standard conditions and under microwave activation in DMF over a period of 10 min. 1,1′-(Hexane-1,6-diyl)bis(3,5-dimethyl-1H-pyrazole) and 1,1′-(benzene-1,4-diyldimethylene)bis(3,5-dimethyl-1H-pyrazole) gave rise to 4-formyl derivatives at both pyrazole rings. 5-Chloro-1,3-dialkyl-1H-pyrazoles failed to undergo formylation according to Vilsmeier-Haak or under microwave activation. 1,1′-Bridged bis-3,5-dimethyl-1H-pyrazoles reacted with 2-sulfanylethanol on heating in the presence of chloro(trimethyl)silane to give the corresponding bridged bis-4-(1,4,6-oxadithiocan-5-yl)-1H-pyrazoles.

5-(2-Thienylsulfanyl)thiophene-2-carbaldehyde: Thioacetalization, chloromethylation, and oxidation

5-(2-Thienylsulfanyl)thiophene-2-carbaldehyde reacted with propane-1-thiol and propane-1,3-dithiol in the presence of chloro(trimethyl)silane to give previously unknown 5-[bis(propylsulfanyl)methyl]-2-(2-thienylsulfanyl)thiophene and 2-[5-(2-thienylsulfanyl)thiophen-2-yl]-1,3-dithiane. Chloromethylation of 5-(2-thienylsulfanyl)thiophene-2-carbaldehyde with formaldehyde in a stream of hydrogen chloride in the presence of zinc chloride resulted in the formation of an oligomeric product consisting of thiophene rings connected alternately by sulfur and methylene bridges. The oligomer is formed via fast polycondensation of the primary chloromethylation product with the initial aldehyde. 5-(2-Thienylsulfanyl)thiophene-2-carbaldehyde was oxidized at the sulfide and aldehyde groups with 30% hydrogen peroxide in glacial acetic to produce 5-(2-thienylsulfonyl)thiophene-2-carboxylic acid.

Studies of thermal decomposition of palladium(II) complexes with olefin ligands

PdCl 2(VTMS) 2 ( 1) , PdCl 2(PTMSA) 2 ( 2), PdCl 2(DMB) 2 ( 3) and PdCl 2(DADMS) 2 ( 4), where VTMS–trimethyl(vinyl)silane, DADMS—diallyldimethylsilane, PTMSA—1-phenyl-2-(trimethylsilyl)acetylene and DMB–2,3-dimethyl-2-butene were prepared and thermal characteristic studied by TG/DTG/DTA techniques. TG/IR method was used for the gas phase studies of ligands and complexes in the range 303–573 K. MS–EI analysis data were applied for elucidation of the metallated species in the gas phase. Thermal analysis results indicate detachment of organic ligand in the first stage of decomposition, whereas the chlorine molecule in the second stage. Metallic palladium was the final product of decomposition, what was confirmed by XRD analysis of the residues heated up to 1273 K. The metallic palladium was formed in the temperature range 478–720 K, what make the complexes ( 1– 4) a promising Chemical Vapour Deposition (CVD) precursors. TG/IR spectra of all palladium(II) complexes revealed bands characteristic for appropriate ligands vibrations, what confirm the proposed mechanism of thermal decomposition. The MS results indicate the palladium fragments detachment in the temperature range 321–548 K. The organic and chlorine species were also observed.

Domino nucleophilic trifluoromethylations of alkyl perfluorodithioesters

Under nucleophilic initiation, alkyl perfluorodithioesters react with trifluoromethyl(trimethyl)silane in a domino process beginning with a thiophilic addition-β-elimination of fluoride ion which leads to a perfluoroketenedithioacetal. Further addition–elimination steps eventually gives a mixture of mono, bis- and tris(trifluoromethyl) vinyl sulfides. Although they are difficult to separate, these new compounds were fully characterized by 19F NMR and mass spectrometry.

Insight into cis‐to‐trans Olefin Isomerisation Catalysed by Group 4 and 6 Cyclopentadienyl Compounds

AbstractIntramolecular isomerisation of the pendant allyl unit present in the model compound [MoH(η5‐C5H4SiMe2CH2CH=CH2)(CO)3] reported before was investigated by DFT calculations. The coordination of CO and the splitting of the agostic Mo–H interactions found in metallacyclic transition states stabilise the cis and trans hydride compounds [MoH(η5‐C5H4SiMe2CH=CHCH3)(CO)3] relative to the corresponding tricarbonyl molybdenum alkyl metallacycles. A comparison with an analogous zirconium system is included. To contrastthese results with the behaviour of metal hydride cyclopentadienyl compounds, which have no intramolecular alkene functionality, group 4 and 6 derivatives such as [Zr(η5‐C5H4SiMe2‐η1‐NtBu)(η5‐C5H4SiMe2CH2CH2‐η1‐CH2)] (2), [MH(η5‐C5HMe4)(CO)3] [M = Mo (3), W (4)], and [ZrH(η5‐C5H4SiMe2‐η1‐NtBu)(η5‐C5H4R)] [R = H (5), SiMe3 (6)] were examined as selective catalysts for the intermolecular isomerisation of the terminal olefins allyltrimethylsilane (A) and 4‐methyl‐1‐pentene (B). Zirconium hydride compounds were the most efficient catalysts. Compound 4 catalysed the same reaction but required heating at 140 °C, whereas compound 3 was inactive due to a dehydrogenation process, which produced the dinuclear compound [Mo(η5‐C5HMe4)(CO)3]2 (7). Reaction of 4 and 5 with the internal alkenes trimethyl(1‐propenyl)silane (C) and 4,4‐dimethyl‐2‐pentene (D) favoured cis‐to‐trans isomer conversion with poor production of the corresponding terminal olefins. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Effect of Plasma Interface Treatment and Cathodic Electrophoretic Coating on Mg Alloys

In this study, plasma treatment using Ar and H2 and plasma polymerization with trimethylsilane (TMS), were carried out to create the interface film systems with a structure of Mg/plasma interlayer/cathodic electrophoretic coating (E-coat) for a magnesium (Mg) alloy AZ31B. The interface adhesion of the coating system was evaluated using N-methylpyrrolidinone (NMP) paint removal test and ASTM tape test conducted under dry and wet conditions. Plasma TMS film could stick the Mg substrate more strongly than E-coat.The surface of samples with different interlayer treatment after NMP test has been observed by SEM. The potentiodynamic study performed on the E-coated samples showed a noticeable reduction of corrosion current, three orders of magnitude less than bare Mg. Salt spray test also was done to confirm the resistance corrosion of E-coat. It was found that plasma interface treatment has the ability of increasing the adhesion of E-coat on Mg alloy more or less, thus restrict access to damaging species that exist in Cl- aqueous environments.

Direct lateral metallation using alkali-metal mediated zincation (AMMZn): SiC–H vs.Si–O bond cleavage

A new application of zincate [(THF)Li(TMP)(tBu)Zn(tBu)] (1) in alkali-metal mediated zincation (AMMZn) is reported by isolating and structurally defining the first intermediates of direct lateral zincation (DlZn) of trimethyl(phenoxy)silane (2) both of which adopt novel six-element {ZnCSiOLiN} ring structures.