E. Hengge

An electrochemical method for the synthesis of silicon—silicon bonds

Abstract An electrochemical method for the preparation of compounds containing Si—Si bonds has been developed and its scope investigated.

Vergleichende 29Si-NMR-untersuchungen an verschiedenen disilanderivaten

Abstract The 29 Si chemical shifts of the series of disilanes Si 2 Ph 6− x Cl x , Si 2 Ph 6− x H x and Si 2 Cl 6− x H x (for x = 0–6) were measured. The dependence of chemical shifts on change of substituents is discussed. It is not possible to predict 29 Si chemical shifts exactly using published models. The influence may be discussed qualitatively, using the sum of electronegativity of substituents. For the series of chlorohydrogen disilanes the coupling constants 1 J (Siue5f8Si), 1 J (Siue5f8H) and 2 J (Siue5f8H) are reported, for the series of phenylhydrogendisilanes most of the 1 J (Siue5f8H) and 2 J (Siue5f8H) are given. For the new compounds prepared physical data, IR and Raman spectra are reported.

Darstellung neuer polycyclischer Methylsilane

Abstract Cyclosilyl alkali compounds are universal reagents for the preparation of polycyclic silanes. Undecamethylcyclohexasilanyl potassium reacts with different chlorosilanes yielding three new methylated polycyclic silanes, which have been isolated and characterized.

Bicyclic silanes from cyclosilane-metal derivatives

Abstract New cyclosilane derivatives with electropositive substituents (mercury, alkali metal) have been prepared from monohalo-undecamethylcyclohexasilane. The availability of these compounds opens up new routes for the preparation of polycyclic and other cyclosilane derivatives. Two bicyclic silanes, bi(undecamethylcyclohexasilanyl) and and bis(undecamethylcyclohexasilanyl)dimethylsilane have been prepared and characterized.

29Si-double-quantum coherence spectroscopy (INADEQUATE). An efficient method for the structure elucidation of silicon frameworks

Abstract The application of the INADEQUATE pulse sequence (both in the one-dimensional and two-dimensional cases) has been extended to study of silicon frameworks. The value of this method for structure elucidation and the determination of 29Siue5f829Si-coupling constants is illustrated for four cyclosilanes.

Permethylheteroatomcyclopolysilane mit Heteroatomen der VI. Hauptgruppe. Darstellung und spektroskopische Eigenschaften

Abstract Group VI permethylheterocyclopolysilanes (SiMe 2 ) n X with n = 4,5,6 and X ue5fb O, S, Se have been synthesized from α,ω-dichloropolysilanes and Li 2 S/Li 2 Se or by simple hydrolysis. From UV spectroscopic results considerable contributions of the heteroatom lone pair electrons to low-energy electron transitions can be derived. Siue5f8Si NMR coupling constants satisfactorily correlate with heteroatom electronegativities, indicating dominant Fermi contact contributions to the magnitude of the corresponding coupling constants.

Synthese und Eigenschaften einiger Ethinylsilane

Zusammenfassung Dichlorodiorganylsilanes react with ethyne and sodium/potassium alloy to give cyclic and catenated organoethynylsilanes.

Die kristallstruktur von octamethylcyclotetrasilan bei 87 K

Abstract The crystal structure of octamethylcyclotetrasilane was determined at 87 K by X-ray diffraction methods: C 8 H 24 Si 4 , monoclinic, P 2 1 / n, a 7.650(2), b 7.452(1), c 13.320(10), A, β 103.48(2)°, Z = 2, d x 1.046 g cm −3 . In the crystal, Si 4 Me 8 molecules are located at crystallographic inversion centers, which constrains the Si 4 -ring to be planar.

Darstellung und Charakterisierung der Phenylfluordisilane Si2Ph6−nFn

Abstract Fluorination of chlorophenyldisilanes with ZnF 2 yields the corresponding fluorophenyldisilanes, if silver powder is used as a catalyst. 1,2-Difluorotetraphenyldisilane is synthesized by UV irradiation of bis-(fluorodiphenylsilyl)mercury, the first known fluorosilylmercury compound. All the eight possible fluorophenyldisilanes, unknown up to now, are characterized by spectroscopic methods.

Radical ions : XXVI. Radical anions of perphenylcyclopolysilanes

Abstract Perphenylcyclopolysilanes [Si(C 6 H 5 ) 2 ] n ( n = 4, 5) are reduced by potassium to radical anions. Their simple ESR spectra demonstrate, that the extra electron is confined to the inner Si n C 2 n skeleton of the uncleaved and presumably planarized cyclopolysilanes.