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The bimolecular gas-phase reaction of ground-state atomic silicon (Si; 3P) with disilane (Si2H6; 1A1g) was explored under single-collision conditions in a crossed molecular beam machine at a collision energy of 21 kJ mol–1. Combined with electronic structure calculations, the results suggest the formation of Si3H4 isomer(s) along with molecular hydrogen via indirect scattering dynamics through Si3H6 collision complex(es) and intersystem crossing from the triplet to the singlet surface. The nonadiabatic reaction dynamics can synthesize the energetically accessible singlet Si3H4 isomers in overall exoergic reaction(s) (−93 ± 21 kJ mol–1). All reasonable reaction products are either cyclic or hydrogen-bridged suggesting extensive isomerization processes from the reactants via the initially formed collision complex(es) to the fragmenting singlet intermediate(s). The underlying chemical dynamics of the silicon–disilane reaction are quite distinct from the isovalent carbon–ethane system that does not depict any reactivity at all, and open the door for an unconventional gas phase synthesis of hitherto elusive organosilicon molecules under single-collision conditions.

A metal‐free, intermolecular syn‐addition of hexamethyldisilane across simple alkenes is reported. The catalytic cycle is initiated and propagated by the transfer of a methyl group from the disilane to a silylium‐ion‐like intermediate, corresponding to the (re)generation of the silylium‐ion catalyst. The key feature of the reaction sequence is the cleavage of the Si−Si bond in a 1,3‐silyl shift from silicon to carbon. A central intermediate of the catalysis was structurally characterized by X‐ray diffraction, and the computed reaction mechanism is fully consistent with the experimental findings., Come together: A highly reactive silylium ion brings together two unreactive reactants while being consumed and regenerated during the catalytic cycle. Unactivated alkenes are thus converted into 1,2‐bissilylated alkanes using simple hexamethyldisilane. The Si−Si bond is cleaved during this process in a kinetically and thermodynamically favored 1,3‐silyl shift from silicon to carbon, as supported by quantum‐chemical calculations.

The structure of the SiC(000-1) surface, the C-face of the {0001} SiC surfaces, is studied as a function of temperature and of pressure in a gaseous environment of disilane (Si2H6). Various surface reconstructions are observed, both with and without the presence of an overlying graphene layer (which spontaneously forms at sufficiently high temperatures). Based on cross-sectional scanning transmission electron microscopy measurements, the interface structure that forms in the presence of the graphene is found to contain 1.4 - 1.7 monolayers (ML) of Si, a somewhat counter-intuitive result since, when the graphene forms, the system is actually under C-rich conditions. Using ab initio thermodynamics, it is demonstrated that there exists a class of Si-rich surfaces containing about 1.3 ML of Si that are stable on the surface (even under C-rich conditions) at temperatures above about 400 K. The structures that thus form consist of Si adatoms atop a Si adlayer on the C-face of SiC, with or without the presence of overlying graphene., Comment: 19 pages with 8 figures, along with 6 pages of Supplemental Material; v2 adds refs. 56,59-62 all being prior work, along with several paragraphs in the Discussion or Summary sections of the manuscript discussing this prior work; v3 corrects several typographical errors

π-Conjugated molecules with electron-donating (D) and -accepting (A) groups such as D-π-A compounds have been focused on strong photo/electro-luminescent materials by intermolecular charge transfer (ICT). However, π-conjugated molecules cause concentration quenching due to π-π stacking in the aggregated state, and these compounds display the low solubility in organic solvents. To develop functional organic luminophores, we synthesized the disilane-modified aromatic compounds. Conformational studies were investigated by X-ray diffraction and variable-temperature NMR experiments. These molecules display high solubility derived from the suppression of intermolecular interaction by large SiMe2 moieties and stimuli-responsive emission properties from σ-π conjugation, displaying blue-green ICT emission in the solid state with higher quantum yield.

A simplified model of Silicon Germanium Chemical Vapor Deposition is proposed for the determination of Vapor – Solid distributions via any precursor route. The incorporation of the atomic element into the crystal lattice imposes to the chemical precursor the loss of all the ligands. Thus, dichlorosilane, silane, and disilane are discriminated on the basis of the amount of the atomic element brought into the equilibrium, instead of being different chemicals. Experimental trends show the ratio relative to silane is 2 for disilane and about ½ for dichlorosilane. The ratio relative to Si{100} is 0.59 for Si{110} and 0.82 for Si{111} for a growth via dichlorosilane and germane. Furthermore, Silicon Germanium alloy content is controlled by a thermodynamic equilibrium and the theoretical VS distribution is demonstrated for a growth via silane and germane. VS distribution of any chemistry onto any substrate orientation can therefore be estimated with the application of a straightforward corrective coefficient to a reference silane and germane chemistry.

Semi-polar (11-22) n-type gallium nitride thin films with various disilane doping levels were deposited via metal-organic chemical vapor deposition. The impact of the dissimilar disilane doping levels on the crystal, morphological, strain, and electrical properties was extensively studied. An X-ray rocking curve analysis demonstrated an improved crystal quality with enhanced terrace-like features using 15 standard cubic centimeters per minute of disilane doping. A closely packed step terrace-like feature was exhibited, reducing the density of arrowhead-like features. This facilitated a smoother surface with a root mean square surface roughness of 5.7 nm. Raman spectroscopy revealed that using an intermediate disilane flux reduced the compressive strain. An electrical analysis also showed that a moderate disilane doping level improved the carrier concentration and mobility to 1.3 × 1018 cm−3 and 99.3 cm2. V−1. s−1, respectively.

The effect of silicon doping on the growth and properties of ∼ 1.0 μ m - thick Al x Ga 1 - x N ( 0.50 ≤ x ≤ 0.55 ) layers grown on semipolar ( 11 2 ¯ 2 ) AlN templates by metalorganic vapour phase epitaxy was studied. The layers were grown with different disilane/group-III precursors ratios that varied from 2.8×10 −5 to 3.4×10 −4 . The surface morphology of the Si-doped ( 11 2 ¯ 2 ) AlGaN layers showed undulations along [ 1 1 ¯ 00 ] AlGaN , AlN with a root-mean square roughness of about 4.0 nm within a scan range of 20 × 20 μ m 2 . Different photoluminescence peaks have been linked to negatively charged cation vacancies ( V III 3 − ) and their complexes with impurities such as V III 3 − - 3 O N 1 + , (V III complex) 1− , and (V III complex) 2− . The optimised AlGaN:Si layer exhibited a carrier concentration of ∼1.2×10 19 cm −3 , a carrier mobility of 30.7 cm 2 /V s, and a resistivity of 0.018 Ω cm , as determined by Hall-effect measurements at room temperature. A correlation between the resistivity and luminescence emission intensities of AlGaN near-band-edge and impurity-related complexes was found.

In the past decade there has been increased interest in utilizing SiGe-heterojunction bipolar transistors (SiGe-HBT) and in particular SiGe-BiCMOS technologies for applications in the mm-and sub-mm-wave range. High data rate communication systems and optical networks for >100Gb/s, industrial and automotive sensors at 120 GHz for velocity and position control as well as imaging systems at >160 GHz for medical and security systems are some examples for these fields of application. Key elements for the continuous improvement of the high frequency performance of SiGe-HBTs are the scaling of vertical and lateral dimensions as well as design optimization to achieve reduced parasitics. In particular the maximum oscillation frequency fmax could be increased in the last years above 0.5 THz. Beside a sufficient high cut-off frequency fT, a reduced base-collector capacitance CBC and low base resistance RB are beneficial for the fmax performance of a SiGe-HBT. In this work we investigate the behavior of the external base resistance RBext for two different epitaxial processes used in SiGe-HBTs with a silane- (SiH4) and disilane-based (Si2H6) precursor. The SiGe-layers were treated by various rapid thermal annealing (RTA). We processed different wafers with an oxide stack usually used in a standard SiGe-BiCMOS process. After the release of certain silicon regions by reactive-ion-etching the epitaxial layers were deposited. First a selective epitaxial silicon buffer was grown within oxide-free windows followed by non-selective growth of a silicon layer, the in-situ boron doped SiGe base layer and an on top silicon cap layer. For the disilane-based process the SiGe layer grows in an amorphous phase whereas for the silane-based process a poly-crystalline film is formed. The growth of the whole Si-SiGe-Si stack was adapted for disilane process in order to reach the same layer thicknesses for both variants inside oxide free windows (single-crystalline regions) as for the original silane-based process. Sheet resistance (Rs) measurements were performed on 49 points across a wafer on the poly crystalline SiGe layer on an oxide. Figure 1 shows the Rs of silane-based (#1) and disilane-based (#3) SiGe-layer after a rapid thermal annealing at 1010°C for 12s. We observe a decrease of Rs by 60% in comparison to the silane-based SiGe-layer. Even for a reduced annealing temperature of 950°C (#2) the Rs dropped down around 30% in comparison to the silan-based variant. Moreover the standard deviation of the sheet resistance in the poly-crystalline regions across the wafer becomes significantly smaller and decreased by a factor of six down to approximately 50 Ohm/square for the disilane-based SiGe stack. Secondary-ion-mass-spectroscopy (SIMS) measurements were used to characterize the boron doping and SiGe-profile inside the crystalline and poly-crystalline regions of the wafers. In the poly crystalline region the germanium and boron concentration of the disilane-based process corresponds to the distribution of the single crystalline region. However we obtain a difference in the doping distribution after epitaxy (Fig. 2a) in comparison to the silane-based process. This difference becomes more significant after the RTA and we observe a quite homogeneous distribution of Ge and boron for the silane-based SiGe-stack whereas a steeper doping is within poly-crystalline layers for the disilane-based process (Figure 2b). We address this disparity in the Ge and boron distribution to differences in the diffusion behavior for the disilane-based layer stack due to i) the deposition as an amorphous Si/SiGe/Si layer and ii) the grain size of the poly-crystals after the final RTA. For our operation point the loading effect during the disilane-based epi-process leads to a 40% increased boron dose in the external base region compared to the silane-based process and without increasing the B doping inside the single crystalline region. This is beneficial for the behavior of RBext. Finally we applied both variants in a standard SiGe-BiCMOS flow. The overall performance of the SiGe-HBT depends of course on several other aspects like base-emitter and base-collector capacitances and the influence of changing one parasitic component has to be carefully evaluated. Nevertheless the external base resistance as well as the contact resistance dropped by 55% and 45%, respectively, for the disilane-based process and show the benefits for the use of this type of epitaxial layer depositions in advanced SiGe-HBTs. Figure 1

A novel approach for the synthesis and identification of higher silanes (SinH2n+2, where n ≤ 19) is presented. Thin films of (d4-)silane deposited onto a cold surface were exposed under ultra-high-vacuum conditions to energetic electrons and sampled on line and in situ via infrared and ultraviolet-visible spectroscopy. Gas phase products released by fractional sublimation in the warm-up phase after the irradiation were probed via a reflectron time-of-flight mass spectrometer coupled with a tunable vacuum ultraviolet photon ionization source. The formation mechanisms of (higher) silanes were investigated by irradiating codeposited 1:1 silane (SiH4)/d4-silane (SiD4) ices, suggesting that both radical-radical recombination and radical insertion pathways contribute to the formation of disilane along with higher silanes up to nonadecasilane (Si19H40).

Today's most frequently used production path for polysilicon and solar grade silicon (SG-Si) is based on thermal decomposition of trichlorosilane (SiHCl 3 ) in a Siemens-type reactor. Due to the batch-wise mode of its operation and its requirement for heating and cooling, the Siemens technology is an energy demanding procedure. As an alternative to this process, SG-Si can be produced through the thermal decomposition of monosilane (SiH 4 ), for example in a fluidized bed reactor or a centrifugal chemical vapour deposition reactor. In order to avoid production of fine particulates and related clogging, this process requires knowledge of the nucleation properties of silane. In this work, the critical concentration for particle nucleation from SiH 4 , diluted in H 2 has been determined for temperatures in the range 400 - 700 °C. For this purpose, we used a free space reactor and an optical particle detector of own design for in-situ monitoring of the reactor exhaust. In a plot of logarithmic critical nucleation concentration against inverse temperature, an almost linear relation was found for temperatures below approximately 500 °C and above approximately 600 °C. Between 500 and 600 °C, a less temperature dependent behavior is observed. Apparent activation energies are estimated to be 32 kcal/mol for temperatures below 500 °C, 8 kcal/mol for temperatures between 500 and 600 °C and 23 kcal/mol for temperatures above 600 °C. The first and last of these values agree well with existing literature. The low temperature dependence in the range 500 °C to 600 °C, however represents a deviation from earlier studies. Investigations of reactor exhaust by GC-MS (gas chromatography - mass spectrometry), allowing detection of the concentrations of higher order silanes (disilane (Si 2 H 6 ), trisilane (Si 3 H 8 ), etc) as function of reactor temperature, suggest that the low temperature dependence of the nucleation concentration for some conditions is related to an increase of the concentration of Si 2 H 6 and Si 3 H 8 at the same temperature range.

We have studied the very low temperature epitaxy of pure Ge and of Ge-rich SiGe alloys in a 200 mm industrial reduced pressure chemical vapour deposition tool. We have, first of all, benchmarked germane (GeH 4 ) and digermane (Ge 2 H 6 ) for the growth of pure Ge. Used Ge 2 H 6 instead of GeH 4 enabled us to dramatically increase the Ge growth rate at temperatures 425 °C and lower (5.6 nm min −1 compared to 0.14 nm min −1 at 350 °C with a Ge 2 H 6 mass-flow one fourth that of GeH 4 ). We have also evaluated at 400 °C, 100 Torr, the impact of the GeH 4 or Ge 2 H 6 mass-flow on the Ge growth rate. For a given Ge atomic flow, the higher surface reactivity of digermane yielded roughly five times higher growth rates than with germane. We have then combined digermane with disilane (Si 2 H 6 ) or dichlorosilane (SiH 2 Cl 2 ) in order to study the GeSi growth kinetics at 475 °C, 100 Torr. While the SiH 2 Cl 2 mass-flow did not have any clear influence on the GeSi growth rate (with a 14 nm min −1 mean value, then), a Si 2 H 6 mass-flow increase resulted in a slight GeSi growth rate increase (from 11 nm min −1 up to 14 nm min −1 ). Significantly higher Ge concentrations were otherwise accessed with dichlorosilane than with disilane, in the 77–82% range compared to the 39–53% range, respectively.

The diverse catalytic activity of the electrophilic borane B(C 6 F 5 ) 3 in reactions of silanes with organic substrates has been exploited extensively in studies that mostly focus on very particular, useful functional group transformations in organic synthesis. This study examines the potential for harnessing the collective, broad scope of these transformations in the preparation of new oligosilane derivatives. Borane-catalyzed hydrosilation, heterodehydrogenative coupling, and dealkylative coupling reactions of a wide range of substrates with the disilane (Ph 2 SiH) 2 were investigated. These allowed new mono- and disubstituted disilanes to be prepared that contain Si O, Si S, and Si C linkages. Challenges and opportunities are described that arise from competing “over-reduction” chemistry, and the sensitivity of the catalysis to both the Lewis basicity and steric bulk of the substrates is examined.

Kinetic theory is used to treat the characteristics of the decomposition of the disilane molecule into two non-identical radicals in a wide range of growth temperatures and at low gas pressure in the reactor. The conditions for determining surface concentration are established and the possibility of the existence of an unambiguous relationship between the rates of decomposition $${v_{SI{H_3}}}$$ and $${v_{SI{H_4}}}$$ various fragments of the molecule is demonstrated. A strong dependence of the rate of decomposition of the molecules of the working gas on its pressure was revealed, which suggests that the film growth rate is mainly dependent on the rate and mode of the pyrolysis process on the surface of the growing layer. It is shown that a model of disilane decomposition into two non-identical fragments with the concurrent transfer of all the hydrogen atoms of the molecule onto the silicon growth surface is most preferrable for an adequate description of the pyrolysis process at temperatures within 400–800°C. Non-physical features of the temperature dependences of the kinetic coefficients appearing in the model of decomposition of disilane into two identical radicals is completely eliminated if the hydrogen atoms are transferred onto the growth surface at the chemisorption stage.

Self-assembly of HgX2 (X− = Br− and I−) with new 1,1,2,2-tetramethyl-1,2-di(pyridin-3-yl)disilane (L) ligand affords single crystals consisting of sinusoidal-strand coordination polymers, [HgX2L]. Specifically, 350 nm UV irradiation of crystalline products [HgBr2L] and [HgI2L] in chloroform media forms in situ single crystals of extraordinary chloro-bridged mercury species, [H2L]2+[Hg2Br4(μ-Br)(μ-Cl)]2− and [H2L]2+[HgI2(μ-Cl)]22−, respectively, in high yields that cannot be synthesized by general synthetic procedures. For all of the compounds, the coordination geometries around the Hg(II) ions along with the mechanistic aspects of the formation of chloro-bridged species are discussed herein.

Synthesis of C 2+ hydrocarbons such as LPG (liquefied petroleum gas) from CO 2 is expected to reduce CO 2 emission by the consumption of fossil fuels. In this study, CO 2 hydrogenation over composite catalysts comprised of Cu–Zn–Al oxide catalyst and HB zeolite was examined for the synthesis of C 2+ hydrocarbons by the combination of methanol synthesis over Cu–Zn–Al oxide and concurrent conversion of methanol over HB zeolite. When a non-modified zeolite was used for the composite catalyst, the yield of C 2+ hydrocarbons was poor ( 2+ hydrocarbons were seriously deactivated. The employment of zeolites modified with 1,4-bis(hydroxydimethylsilyl) benzene remarkably improved the catalytic activity of the corresponding composite catalysts to produce C 2+ hydrocarbons in yields of more than 7C-mol%. The best yield of C 2+ hydrocarbons became approximately 12.6C-mol% under a pressure of 0.98 MPa. The disilane modification produced hydrophobic zeolites showing water contact angles more than 130°. The disilane compound was converted to some condensed aromatics during CO 2 hydrogenation at 300 °C, and the hydrophobicity was maintained even after the reaction. The enhanced catalytic activity is caused by suppressing the deactivation of the strong acid sites of HB zeolite with the hydrophobic surface. This improved composite catalyst will promote the production of C 2+ hydrocarbons from CO 2 even under low pressure conditions.

In this study, silicon nitride thin films are deposited on organic polyethylene-naphthalate (PEN) substrates by laser assisted plasma enhanced chemical vapor deposition (LAPECVD) at a low temperature (150 &deg, C) for the purpose of evaluating the encapsulation performance. A plasma generator is placed above the sample stage as conventional plasma enhanced chemical vapor deposition (PECVD) configuration, and the excimer laser beam of 193 nm wavelength illuminated in parallel to the sample surface is coupled to the reaction zone between the sample and plasma source. Major roles of the laser illumination in LAPECVD process are to compete with or complement the plasma decomposition of reactant gases. While a laser mainly decomposes ammonia molecules in the plasma, it also contributes to the photolysis of silane in the plasma state, possibly through the resulting hydrogen radicals and the excitation of intermediate disilane products. It will also be shown that the LAPECVD with coupled laser illumination of 193 nm wavelength improves the deposition rate of silicon nitride thin film, and the encapsulation performance evaluated via the measurement of water vapor transmission rate (WVTR).

The Muller-Rochow direct process (DP) for the large-scale production of methylchlorosilanes Men SiCl4-n (n=1-3) generates a disilane residue (Men Si2 Cl6-n , n=1-6, DPR) in thousands of tons annually. This report is on methylchlorodisilane cleavage reactions with use of phosphonium chlorides as the cleavage catalysts and reaction partners to preferably obtain bifunctional monosilanes Mex SiHy Clz (x=2, y=z=1; x,y=1, z=2; x=z=1, y=2). Product formation is controlled by the reaction temperature, the amount of phosphonium chloride employed, the choice of substituents at the phosphorus atom, and optionally by the presence of hydrogen chloride, dissolved in ethers, in the reaction mixture. Replacement of chloro by hydrido substituents at the disilane backbone strongly increases the overall efficiency of disilane cleavage, which allows nearly quantitative silane monomer formation under comparably moderate conditions. This efficient workup of the DPR thus not only increases the economic value of the DP, but also minimizes environmental pollution.

SiiCle is shown to be a catalyst for the cyclo-trimerization of both terminal and non-temiinal alkynes between 160-200 °C, e.g., cyclo-trimerization of PhC*CPh gave CePhg in 60% yield. The reaction involves formation of SiCU radicals. Si2(OMe)6 also catalyzes the cyclotrimerization of alkynes, but with lower conversions (yields). This represents the second example of such reactions facilitated by a non-metallic catalyst, as well as the first example proceeding by a radical pathway. 1. Reprinted with permission of American Chenucal Society. J. Am. Chem. Soc. 1998. 120. 6834-6835. 2. Graduate student and professor, respectively. Department of Chemistry, Iowa State University. 3. Primary researcher and author. 4. Author for correspondence.

Herein we describe a general, mild and scalable method for deuterium incorporation by potassium methoxide/hexamethyldisilane-mediated dehalogenation of arylhalides. With CD3CN as a deuterium source, a wide array of heteroarenes prevalent in pharmaceuticals and bearing diverse functional groups are labeled with excellent deuterium incorporation (>60 examples). The ipso-selectivity of this method provides precise access to libraries of deuterated indoles and quinolines. The synthetic utility of our method has been demonstrated by the incorporation of deuterium into complex natural and drug-like compounds.

Host-guest chemistry was performed with disilane-bearing crown ethers and the ammonium cation. Equimolar reactions of 1,2-disila[18]crown-6 (1) or 1,2-disila-benzo[18]crown-6 (2) and NH4PF6 in dichloromethane yielded the respective compounds [NH4(1,2-disila[18]crown-6)]PF6 (3) and [NH4(1,2-disila-benzo[18]crown-6)]PF6 (4). According to X-ray crystallographic, NMR, and IR experiments, the uncommon hydrogen bonding motif O(Si)∙∙∙H could be observed and the use of cooperative effects of ethylene and disilane bridges as an effective way to incorporate guest molecules was illustrated.

Density functional theory (DFT) calculation has been used to reveal the mechanism of Pd-catalyzed disilylation of carbene, which is a pathway to construct disilylmethane derivatives. The DFT calculations indicate that the reaction starts with carbenation of a Pd(0) catalyst. Oxidative addition of disilane can then generate a carbene-coordinated disilylpalladium intermediate. Carbene insertion into the Pd–Si bond followed by reductive elimination gives the disilylmethane product and regenerates the Pd(0) catalyst with the formation of two C–Si bonds. The rate-determining step of this reaction is the carbenation step. The computational results show that the phosphine ligand is unfavorable for this type of reaction because of its high dissociation energy. In this type of reaction, a smaller substrate is favorable for the oxidative addition step because the weaker steric repulsion leads to a lower activation free energy of the oxidative addition step. The computational results also reveal that the reactivity of digermane and distannane is higher than that of disilane, which can be attributed to their low bond dissociation energies.

This work focuses on the study of the formation of amorphous silicon clusters embedded in SiNx thin films prepared by low-pressure chemical vapor deposition technique at a temperature of 1023 K by using a mixture of silane (SiH4) and ammonia (NH3). The deposition process is modeled via kinetic Monte Carlo simulation on a triangular lattice. The distribution of ammonia molecules in the simulation matrix is described using our previous pattern. This pattern includes adsorption and migration microscopic processes. The influences of the NH3/SiH4 gas flow ratio and the deposition time on the deposition kinetics are analyzed. The obtained results describe well the different stages of the nitrogen doped silicon deposition process. Indeed, an increase in the gas flow ratio leads to the formation of a high density of smaller amorphous silicon clusters. Moreover, larger clusters can be formed by increasing the deposition time. Simulation results are also compared to our previous results to better understand, on the one hand, the interest of using disilane instead of silane in order to make such deposits, and on the other hand to evaluate the role of ammonia in the SiNx film deposition process.

This chapter discusses the ultrahigh vacuum chemical vapor deposition (UHV/CVD) is compared to other silicon and silicon–germanium epitaxial deposition methods with emphasis on the ultralow temperature regime below 700°C and on 200 to 300 mm substrate size. It explores the UHV low-temperature reaction-limited silane deposition characteristics. The adsorption coefficients of silane, disilane, and trisilane molecules under UHV conditions were found to be dissimilar but only weakly temperature-dependent. Contamination originating from the reactor’s inner periphery is minimized by evacuating the chamber to UHV pressures. Epitaxial UHV/CVD of silicon–germanium is typically achieved by adding diluted germane or digermane to the precursor gas flow. The use of low temperatures during growth, as enabled by UHV/CVD, is expected to result in better alloy metastability because relaxation exhibits stronger thermally activated behavior as compared to growth. The concept of nucleation delay was extended to UHV/CVD in order to further reduce deposition temperatures.

The first example of metal-free hydrosilylation polymerization between dienes and disilanes is developed by using a borane catalyst, B(C6F5)3 to replace precious transition-metal-based systems. Under the easy-to-handle and mild conditions, a step-growth polymerization of two readily available diene and disilane units was achieved with high degrees of polymerization. Various combinations of dienes and disilanes produced polycarbosilanes with a broad range of structures and properties.

By using a strained four-membered ring disilane (3,4-benzo-1,1,2,2-tetraethyldisilacyclobutene) and CsF, a wide range of aryl, alkenyl, alkynyl, benzyl, allyl, and alkyl halides was successfully carboxylated under an ambient CO2 atmosphere (CO2 balloon) at room temperature within 2 h. In this carboxylation, a highly reactive silyl anion, which is generated from the disilane and CsF, is a key to facilitating the formation of a carbanion equivalent. The resulting anionic species can be trapped with CO2 to produce carboxylic acids with high efficiency.

Germanium nanoparticle growth on SiO2 proceeds via defect-mediated nucleation and particle density can be enhanced by chemically treating the SiO2 with SiHx. The influence of SiHx fragments on SiO2 surface sites is studied using a fluorescent probe-based technique to understand the chemical nature of the inherent defect trapping sites and the chemical nature of the additional trapping sites formed by SiHx. Oxygen-vacancy sites on SiO2 are the inherent sites for defect-mediated nucleation. SiHx fragments, generated by cracking disilane on a hot tungsten filament, are shown to react with strained siloxane sites, leading to a conversion of these strained siloxane sites into a different low density defect site that is shown to display reactive characteristics similar to the oxygen-vacancy defect sites. Previous work demonstrating an increased density of Ge nuclei on SiO2 surfaces with increasing SiHx exposure is interpreted in the context of the current experimental results. © 2015 American Institute of Chemical Engineers AIChE J, 2015

The Au/TiO2-catalyzed reaction between 1,1,2,2-tetramethyldisilane and terminal alkynes yields substituted 1,4-disila-2,5-cyclohexadienes (1,1,4,4-tetramethyl-1,4-dihydro-1,4-disilines) in moderate to good yields. The reaction proceeds via initial Si–Si activation of disilane by gold nanoparticles to form with alkynes isolable cis-1,2-disilyl adducts (cis-1,2-bis(dimethylsilyl)ethenes), which, under the reaction conditions, undergo a Au-catalyzed dehydrogenative cycloaddition to a second alkyne molecule, forming the final cycloadducts.

1,2-dimethyl-1,1,2,2-tetraphenylsulfonato disilane (DMTPS) has been prepared by sulfonation of 1,2–dimethyl–1,1,2,2–tetraphenyl disilane and its catalytic activities in transesterification of palm oil and esterification of fatty acids with secondary alcohols have been studied. The DMTPS was characterized by FT–IR, 1H–NMR and 13 C–NMR and showed that all phenyl rings have been sulfonated. The transesterification of crude palm oil with methanol using DMTPS as the catalyst performed in an autoclave under a temperature ranging from 120 °C to 160 °C. The total ester yielded from transesterification was 96%. Then, the catalyst was recovered (97%) and reused in three other successive transesterifications at 160 °C to see the catalyst activity and stability. It was found that the catalyst activities remain unchanged shown from the transesterification yield which was 96% in each reaction. The FT–IR of the used DMTPS catalyst was also very similar to that of the original one. The DMTPS catalyst also used in the esterification of long chain fatty acids with two secondary alcohols i.e. 2–propanol and 2–butanol at 150 °C, provided yield of 86% and 48% of esters respectively. These show that the DMTPS catalyst is a stable catalyst in moderate temperature and show a good performance in both transesterification and esterification involving secondary alcohols.

Treatment of the unsymmetric disilane (SiH3) (SiMeBut2) (1) containing one Si–Si single bond with Pt(dcpe) (PEt3)2 (dcpe = Cy2PCH2CH2PCy2) in the ratio of 1:1 leads to a stable disilanylplatinum hydride complex {(SiH2) (SiMeBut2)}(H)– PtⅡ(dcpe) (2), which is one of the very few examples of bis(phosphine) (hydrido) platinum(Ⅱ) complexes bearing silyl ligands with Si–Si single bonds structurally characterized by single crystal X-ray analysis and multinuclear NMR spectroscopic studies.