Five-coordinate potassium dihydridosilicates: synthesis and some aspects of their reactivity

Molecular Main Group Metal Hydrides

This review serves to document advances in the synthesis, versatile bonding, and reactivity of molecular main group metal hydrides within Groups 1, 2, and 12-16. Particular attention will be given to the emerging use of said hydrides in the rapidly expanding field of Main Group element-mediated catalysis. While this review is comprehensive in nature, focus will be given to research appearing in the open literature since 2001.

Sol-Gel Chemistry of Hydrogenosiliconates: The Role of Hypervalent Silicon Species

The hydrolysis of organic silicates ( mainly Si(OEt)4: [TEOS] and Si(OMe)4: [TMOS]) is the key reaction in sol gel process for preparation of silica. The mechanism of this reaction is not well known because of the competition taking place between hydrolysis itself and condensation reactions (homo or heterocondensations) but also because of redistribution reactions which take place competitively. Furthermore the competition between these steps depends also on the catalysis (acid,basic or nucleophilic) [1, 3].

29Si NMR studies on the mechanism of dehydrocoupling of hydrosilanes with hydroxylic reagents in DMF — The role of DMF

Interactions of DMF with hydrosilanes were studied by 29Si NMR. New resonance signals were observed in the 29Si NMR spectra of HMe2SiOSiMe2H and some (alkoxy)hydrosilanes for high ratios of concentrations [DMF]/[H-silane] at 25 °C. The intensities of new signals increased several times at –60 °C. It seems that these new resonances correspond to molecular complexes of DMF with hydrosilanes. The role of DMF in the mechanism of dehydrocoupling of hydrosilanes with hydroxylic reagents in the presence of Zn(II) and Cd(II) halides (X = Cl, Br, I) is discussed. Some common features of the reaction mechanism with the mechanism of hydride transfer from the Si—H bond to the carbenium ion are discussed.Key words: hydrosilanes, hydroxylic reagents, reaction mechanism of dehydrocoupling in DMF, 29Si NMR.

Unprecedented double nucleophilic addition of a hydride at a central carbon of an eta3-allyl ligand

Treatment of eta(3)-allyl compound [Cp(2)Mo(eta(3)-C(3)H(5))](+)(1; Cp =eta(5)-C(5)H(5)) with MH (M = Li, Na) resulted in reduction of the allyl ligand to give propane. Deuterium-labeling studies were used to trace the origins and fates of the hydrogen atoms. The mechanism is discussed in light of the HSAB principle. The studies showed that the formation of propane can be explained by 1,2-hydrogen migration from the central to the terminal carbon of the allyl ligand, and the subsequent double nucleophilic addition of the hydride at the central carbon.