Silenes complexes

During recent years, fascinating developments have occurred in the area of r 2-silene complexes, which opened up to totally new chemistry. Some of the highlights will be presented in this section. The first investigations of coordination compounds of silenes were carried out by means of matrix isolation techniques at very low temperatures. In particular, photochemical methods proved to be most effective... 

Mori M (2005) Synthesis and Reactivity of Zirconium-Silene Complexes. 10 41-62... 

Mori M (2005) Synthesis and Reactivity of Zirconium-Silene Complexes. 10 41-62 Moriuchi T, Hirao T (2006) Ferrocene-Peptide Bioconjugates. 17 143-175 Morokuma K, see Musaev G (2005) 12 1-30... 

Presumably, carbosilane formation in the catalytic cycle occurs via an analogous intermediate silene complex in which one of the two hydrides is replaced by a SiMe3 group. Subsequent migration of the silyl group to the carbon of the silene would produce a new carbosilyl ligand. 

Based on these results, Sakurai and coworkers proposed for the addition of alcohols to the silene 44 the mechanism shown in Scheme 14. In the first stage the silene forms an alcohol-silene complex 48 as suggested by Wiberg61, and this stage is followed by an intramolecular proton migration in 48 (the first-order rate constant, k ) which competes with the intermolecular proton transfer from an additional external alcohol (the second-order rate constant, ko). These two processes give the syn and anti addition products, respectively. 

When a methylene or dimethylgermyl group intervenes between the transition metal and the silyl group, as in 164, photolysis results in rearrangement to 165, which appears, for the methylene case, to involve the intermediacy of a metal-silene complex (Scheme 25). 

Ru(H)(SiMe3)(PMe3)4] with HSiMe2CH2Cl [Eq. (19)] or, alternatively, by chlorination of the Ru-H bond in the silene complex [Ru( tl)2Crq2-CH2SilV1c2)(PMcy), ].142... 

Possible Reaction Course for the Formation of Zirconium-Silene Complex. . 51... 

Abstract When Cp2ZrCl2 was treated with 2 equivalents of Me2PhSiLi, a zirconium-silene complex was formed. In the presence of alkyne, diarylalkyne reacted with silene coordinated with zirconium to give silazirconacyclopentene, which was hydrolyzed to give vinylsilane. On the other hand, dialkylalkyne inserted into zirconium-silene complex to give silazirconacyclopentene, which was hydrolyzed to give allylsilane. Formation of the zirconium-silene complex was monitored by H NMR spectra. 

Keywords Zirconium-silene complex Silene Azazirconacyclopropane Azazirconacyclopentene Cp2Zr (SiMe2Ph)... 

Since silene is an unstable species, various transition metal-silene complexes coordinated by the silicon-carbon double bond have been reported. In 1970, Pannel reported the formation of silene by irradiation of an iron complex (Eq. 6) [8]. He obtained an iron-TMS complex that was apparently formed from silene and an iron-hydride complex generated from the starting iron complex by /3-hydrogen elimination [8]. Wrighton confirmed the existence of tungsten-and iron-silene complexes by examination of NMR spectra obtained at low temperature (Eqs. 7 and 8) [9]. 

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