Edward Carberry

Permethylpolysilanes: Silicon Analogs of Hydrocarbons: Cyclic polysilanes resemble aromatic hydrocarbons in electronic and chemical properties.

Studies of the spectra of cyclopolysilanes have led to several significant conclusions. These molecules possess both easily ionized Si-Si bonding electrons and low energy delocalized antibonding orbitals, and can therefore serve either as electron donors or acceptors. This model explains the similarity in properties between cyclopolysilanes and aromatic hydrocarbons. Further investigations of cyclopolysilanes seem likely to provide the key to understanding of controversial questions of bonding in metalloid compounds even as studies of their carbon analogs, the cyclic and cage hydrocarbons, have been crucial to present knowledge of organic stereochemistry and reaction mechanisms. The reactions of cyclopolysilanes are not only interesting in themselves, but have opened the way to the synthesis of complex polysilanes and thus to whole new areas of study. Improved methods of synthesis and isolation are needed, but the number and kinds of compounds that can be prepared seem almost limitless. Perhaps a polymetal chemistry comparable in breadth and variety to carbon chemistry is now developing.

The preparation and spectroscopic properties of the permethylcyclopolygermanes

Abstract The preparation and characterization of the new five- and seven-membered cyclopolygermanes, decamethylcyclopentagermane and tetradecamethylcycloheptagermane, are reported. An improved preparative method is also presented for the hexamer, dodecamethylcyclohexagermane. In addition, ultraviolet, NMR, infrared, and mass spectral studies of all three compounds are described and discussed. All attempts to reduce the cyclopolygermanes to anion radicals for subsequent electron spin resonance studies were unsuccessful.

Proton NMR spectra of methylpolysilanes

Abstract Proton nuclear magnetic resonance spectra have been determined for the linear permethylpolysilanes through Si10, the cyclic permethylpolysilanes (SiMe2)n where n = 5 through 7, and eight monosubstituted polymethyldisilanes and trisilanes. In linear permethylpolysilanes, the chemical shift of the methyl protons generally appears at lower field as the distance of the methyl group from the end of the chain increases. Electronegative substituents decrease the shielding of methyl protons on the silicon atom to which they are attached, the effect decreasing in the order Cl>phenyl> O>H. The coupling constant J(SiCH3) decreases slightly withincreasing catenation, in the same way as found previously for analogous polymethyltin compounds9, but differences are quite small for the polysilanes.

Consumer chemistry demonstrations

Demonstrating the hazards of mixing an acidic cleaner with bleach and the light-absorbing ability of sunscreens.