Direct Reaction of Silicon with α−ω Dichloroalkanes:  Direct Formation of Dichlorosilacyclopentane

Abstract

The direct reaction of silicon with 1,4-dichlorobutane in the presence of a CuCl catalyst gives high selectivity for dichlorosilacyclopentane under some conditions. The effects of residence time, temperature, and promoters are explored, and the highest selectivity occurs at short residence time and in the presence of a Cd promoter. The reaction of silicon with methyl chloride is discussed as well. The methyl chloride reaction is usually promoted by Zn and not by Cd. The reaction of silicon with 1,3-dichloropropane and with 1,5dichloropentane was also explored; however poor selectivity to any product occurred with these other dichloroalkanes. The origin of the selectivity for the silacyclopentane is discussed in terms of low activation energy for ring closure in the five-membered ring case. Other low activation options such as reaction of silylene intermediate with C-H vs C-Cl prevent good selectivity in the dichloropropane and dichloropentane reactions.

Activations of all Bonds to Silicon (Si–H, Si–C) in a Silane with Extrusion of [CoSiCo] Silicide Cores

“…A few studies have provided mechanistic information on the Direct Process, which is thought to proceed through silylene intermediates that engage in SiC and SiCl bond-forming steps. − ,− However, detailed studies of the reverse process, in which a silicide is produced by Sielement bond activations in a silane, have not been well described . This report describes a molecular model system in which the generation of Co-silicide complexes results from activations of all bonds in PhSiH 3 or SiH 4 by reaction with a Co­(I) complex, Na + (THF) 6 {[BP 3 i Pr ]­CoI} − ( 1 ), to produce dicobalt species containing unusual CoSiCo silicide cores.…”