| Abstract: | Carbosilanes are compounds in which the elements carbon and silicon occupy alternate positions in the molecular framework. Formal replacement of every second carbon atom in the diamond lattice by a silicon atom gives silicon carbide, which exists, however, in several modifications characterized by different stacking orders. The SiC lattice is the basis of most carbosilanes.[1] These are divided on the basis of structural differences into carborundanes, silascaphanes, and molecules that no longer contain elements of the silicon carbide structure. In the carborundanes the Si–C six-membered rings are arranged in the chair form, in the silascaphanes in the boat form. The molecular framework of the third group is derived from barrelane and asterane. The reactivity of the carbosilanes is determined mainly by the substituents on the skeletal atoms. The presence of SiH or Si–halogen groups leads to a high reactivity, while derivatives with organic groups on the silicon atoms and CH2 or CH groups in the skeleton are much less reactive. However, even such CH2 and CH groups permit certain characteristic reactions. Because of their structural features and the range of substituents that can be introduced, the carbosilanes are presently of considerable interest with respect to technological developments as precursors for ceramics. |
