Bonds bismuth-silicon

Like nitrogen, phosphorus, arsenic, antimony and bismuth usually bond to silicon in the III valence state. NMR and vibrational spectra indicate a pyramidal structure... 

The silicon-bismuth bond has been demonstrated in a number of compounds such as Bi(SiF3)3, a volatile crystalline compound184 which decomposes on heating it is air and moisture sensitive. Germanium-bismuth compounds can be prepared by the use of Bi(SiEt3)3 (equations 52 and 53).185... 

Silicon carbide is comparatively stable. The only violent reaction occurs when SiC is heated with a mixture of potassium dichromate and lead chromate. Chemical reactions do, however, take place between silicon carbide and a variety of compounds at relatively high temperatures. Sodium silicate attacks SiC above 1300°C, and SiC reacts with calcium and magnesium oxides above 1000°C and with copper oxide at 800°C to form the metal silicide. Silicon carbide decomposes in fused alkalies such as potassium chromate or sodium chromate and in fused borax or cryolite, and reacts with carbon dioxide, hydrogen, air, and steam. Silicon carbide, resistant to chlorine below 700°C, reacts to form carbon and silicon tetrachloride at high temperature. SiC dissociates in molten iron and the silicon reacts with oxides present in the melt, a reaction of use in the metallurgy of iron and steel (qv). The dense, self-bonded type of SiC has good resistance to aluminum up to about 800°C, to bismuth and zinc at 600°C, and to tin up to 400°C a new silicon nitride-bonded type exhibits improved resistance to cryolite. 

Many elemental metalloid surfaces, on the other hand, are considered to have perturbed structure when clean. Examples are the (HI), (HO), and (100) faces of silicon and germanium 126a, 338), the (HI) and (100) faces of diamond 286, 287), the (1120) planes of bismuth and antimony 297), and the (1000) surface of tellurium 325). It is believed that the (HI) and (100) planes of GaAs have altered periodicities also 133, 339). Distortions of all these covalently bonded surfaces are explained by assuming configurations that partially satisfy the free valence of the strongly directional cut bonds. These structures are complex and not yet completely determined 340-344). 

What type of compounds will be covered in this overview. Strictly, only compounds which have at least one metal-carbon bond (with the exception of metal carbides) are called organometaiiic. However, this definition was not adopted in this chapter because many families of compounds that are relevant in organometaiiic chemistry would not be included (e.g., alkoxides). By metal we mean any element from groups 1 (except hydrogen), 2, 3 (including lanthanides and actinides), 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 (except boron), 14 (except carbon and silicon), and 15 (antimony and bismuth only). Most of the available thermochemical data for all these species are freely available in a single on-line database the NIST Chemistry WebBook Unless stated otherwise, all the data included in this chapter were quoted from that reference. 

---