Strained silicon-containing

The situation for strained silicon-containing ring compounds has become if anything, more confusing since the previous review. The only new experimental data, are those for a series of siletanes " (silacyclobutanes), shown in Table 8. From these, strain enthalpies in the range of 109-120 kJmol can be calculated. These are slightly larger than an... 

The spectra of samples with layers which contain strained silicon bonds - Ge/Si quantum dots and Si Er - are characterized by the developed fine structure in the energy range of 101 - 104 eV. Nobody has ever observed such fine structure up to now. Conesponding energy levels in the conduction bands can participate in the luminescence spectra. The most striking thing here is a close similarity of the Ge/Si spectra and Si Er samples. Nevertheless, one should remember that surfaces of practically all nanostmctures were capped with thin protecting epitaxial layer of... 

For the selectivity of the cross-metathesis reaction with ethylene (ethenolysis) the choice of a suitable catalyst and a cycloolefin for which ring-opening is energetically favorable as well as the optimization of the reaction conditions are crucial. Cycloolefins with a norbomene skeleton were chosen for their high ring strain. The silicon-containing educts can be obtained by hydrosilylation of norbomadiene with the corresponding silanes. 

Several compounds containing Tt-bonds show reactions with 1 which most likely proceed via [2+1] or [4+1] cycloaddition processes, but no detailed mechanistic studies have been performed so far. Not unexpectedly, the electron-rich species 1 preferentially reacts with electron-poor substrates, and ring-strained or dipolar intermediates rearrange or react further to more stable products in a sometimes rather complicated and surprising fashion. In a few cases even the pentamethylcyclopentadienyl substituents at silicon are involved in the reaction pathways. 

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