Search results for "silane"

Die alkoholyse des triethylsilans katalysiert von [(CH3)3P]2Ru(CO)2Cl2

1983

Abstract [(CH 3 ) 3 Pl 2 Ru(CO) 2 Cl 2 is an effective catalyst for the reaction of alcohols with triethylsilane. The rate of this reaction varies with the substituents in the hydroxy compound; it is fastest for short primary alcohols. Even in the presence of groups which can be hydrosilated (CC triple or double bonds, as well as ketones), a hydroxy group reacts preferably and completely with the silane. Kinetic experiments have been performed with the system Et 3 SiH/CH 3 CH(OH)COOEt/Ru complex.

Electronic structure of polysilanes: influence of substitution and conformation

1993

Abstract The valence effective Hamiltonian (VEH) quantum-chemical approach is used to investigate the electronic properties of polysilane. The valence band structure calculated for this fully saturated polymer is analyzed in terms of orbital contributions and compared to that of the closely related carbon polymer, polyethylene. The effects of alkyl substitution and silicon backbone conformation are studied by elucidating the modifications that these structural changes induce on the electronic valence band structure of all-trans unsubstituted polysilane. The VEH results predict a decrease of the band gap upon alkyl substitution and on going from helical to all-trans conformations.

Intramolecular coupling of acetylenic groups of bis(alkynyl)phosphanes and silanes mediated by benzynezirconocene: a route to new mono- and tricyclic…

2004

Benzo-zirconacyclohexadiene-phospha or silacyclobutene fused ring systems are easily prepared via a benzynezirconocene intermediate by means of thermolysis of Cp 2 ZrPh 2 in the presence of bis(alkynyl)phosphanes or silanes. These polyunsaturated systems are the source of a variety of new mono- or tricyclic heterocycles incorporating either one or two heteroatoms.

Ferrocenyl-functionalized long chain branched polydienes

2009

A convenient two-step approach for the synthesis of ferrocenyl-functionalized long chain branched polydienes, based on both butadiene and isoprene, respectively, is presented. Classical living anionic polymerization was used to synthesize different AB n type poly(diene) macromonomers with moderate molecular weights between 1700 and 3200 g/mol and narrow polydispersity. Quantitative end-capping with chlorodimethylsilane resulted in the desired AB n macromonomer structures. In the ensuing Pt-catalyzed hydrosilylation polyaddition, branched, functionalized polydienes were obtained by a concurrent AB n + AR type of copolymerization with mono-and difunctional ferrocenyl silanes (fcSiMe 2 H or fc…

Molecular “Floppyness” and the Lewis Acidity of Silanes: A Density Functional Theory Study

2001

A comprehensive set of Lewis acid-base adducts of silanes was investigated by means of the density functional theory geometry optimization [B3LYP/6−31G(d)], and thermochemical calculations, [B3LYP/6−311+G(2d,p)//B3LYP/6−31G(d)]. Complex formation was found to weaken Si−Cl and Si−Br bonds more than Si−F or Si−H bonds. Comparable distances between Si and a Lewis base L (L = NH3, OH2, F−) are shorter in hexa- than in pentacoordinated complexes. The molecular structures of the pentacoordinated Si complexes allowed for a mapping of an SN2 reaction pathway by correlating the lengths of the Si−X and Si−L bonds. Complex formation was found to be exothermic for most of the coordination compounds, an…

Experimental Investigations and ab Initio Studies on Hexacoordinated Complexes of Dichlorosilane

1998

Dichlorosilane, SiH2Cl2, forms two different kinds of coordination compounds with pyridine and 3-picoline:  the simple adduct trans-SiH2Cl2(L)2 and the ionic complex [SiH2(L)4]Cl2·4CHCl3 (L = pyridine, 3-picoline). The adducts trans-SiH2Cl2(py)2, 1, and trans-SiH2Cl2(3pic)2, 2, form directly from the reaction of bis(dichlorosilyl)methylamine, NMe(SiHCl2)2 with pyridine (py), and 3-picoline (3pic). Reaction of 1 with an excess of pyridine in chloroform yielded [SiH2(py)4]Cl2·4CHCl3, 3. The molecular and crystal structures of 1−3 were investigated by single-crystal X-ray diffraction. The Si atoms of all three compounds are hexacoordinated and lie on centers of inversion. The basic structural …

Challenges in the Electrochemical Synthesis of Si 2 Cl 6 Starting from Tetrachlorosilane and Trichlorosilane

2022

Synthesis of Chiral Catalyst Modifiers by Hydrosilylation of Cinchonidine and Their Application in the Hydrogenation of 1-Phenylpropane-1,2-dione and…

2005

Four new chiral modifiers were synthesized in order to investigate the effect of distal modifier substitution in the hydrogenation of ethyl pyruvate and 1-phenylpropane-1,2-dione on a supported Pt/Al2O3 catalyst. The chiral modifiers were prepared in good to moderate overall yields by Pt-catalyzed hydrosilylation of 9-O-TMS-protected cinchonidine with triethylsilane, triphenylsilane, bis(dimethylsilyl)ethane and (+)-(R)-methyl(1-naphthyl)phenylsilane followed by cleavage of the silyl ether protective group. Comparison of the synthesized modifiers in enantioselective hydrogenation using cinchonidine as reference modifier is reported, as well as details on their synthesis and characterization…

Germil-un silil-heterociklu sintēze, struktūra un bioloģiskā aktivitāte

2013

Elektroniskā versija nesatur pielikumus

Direct observation of a borane–silane complex involved in frustrated Lewis-pair-mediated hydrosilylations

2014

Perfluorarylborane Lewis acids catalyse the addition of silicon–hydrogen bonds across C=C, C=N and C=O double bonds. This ‘metal-free’ hydrosilylation has been proposed to occur via borane activation of the silane Si–H bond, rather than through classical Lewis acid/base adducts with the substrate. However, the key borane/silane adduct had not been observed experimentally. Here it is shown that the strongly Lewis acidic, antiaromatic 1,2,3-tris(pentafluorophenyl)-4,5,6,7-tetrafluoro-1-boraindene forms an observable, isolable adduct with ​triethylsilane. The equilibrium for adduct formation was studied quantitatively through variable-temperature NMR spectroscopic investigations. The interacti…