Reaction of Alkyn-1-yl(diorganyl)silanes with 1-Boraadamantane: Si-H-B Bridges Confirmed by the Molecular Structure in the Solid State and in Solution
作者:Bernd Wrackmeyer、Wolfgang Milius、Oleg L. Tok
DOI:10.1002/chem.200304961
日期:2003.10.6
4-methylene-3-borahomoadamantane derivatives 4 quantitatively and selectively by 1,1-organoboration. An electron deficient Si-H-Bbridge was present in the product. The analogous reaction of 1 with an alkyn-1-yl-disilane 3 gave the corresponding alkene derivative 5, however, without the Si-H-Bbridge. Evidence for the Si-H-Bbridge in 4 was given by IR data, an extensive set of NMR spectroscopical data ((1)H
perpendicularly to each other. The W–Si bond distances of 5 are comparable to those of typical base-stabilized tungsten silylene complexes. The C–C bond distance is much longer than a typical C≡C triple-bond distance and is similar to a typical C═C double-bond distance. The bonding nature and electronic structure of 5 were disclosed by a DFT study of the model complex Cp(CO)2W(SiH2)(μ-CC)(SiH2)W(CO)2Cp
Photoirradiation of polysilacycloalkynes in the presence of acetone provides the acetone adducts of bicyclic silacyclopropenes. Ringcontraction of polysilacycloalkynes proceeds via two different pathways; one is a process via bicyclic silacyclopropene formed by rearrangement of the silicon atom adjacent to acetylene carbons and another is a direct desilylation process.