Silicon compounds nitrogen-containing

The study of compounds containing pentacoordinate silicon atoms currently represents one of the main areas of research in silicon chemistry. This is evident from the numerous reviews and proceedings published on this topic in recent years.112 Most of the pentacoordinate silicon compounds described in the literature are either salts with A5.S7-silicate anions or neutral silicon complexes with a 4+1 coordination to silicon. This review deals with a completely different class of pentacoordinate silicon compounds zwitterionic A S /-silicatcs. These molecular compounds contain a pentacoordinate (formally negatively charged) silicon atom and a tetracoordinate (formally positively charged) nitrogen atom. 

Lukevics, E. Biological activity of nitrogen-containing organosilicon compounds. In Biochemistry of silicon and related problems, pp. 435—445. New York Plenum Press, 1978... 

E. Fleury, S. Halila, H. Driguez, S. Cottaz, T. Hamaide, S. Fort, FR 2 900 931, 16/11/2007. Hybrid compounds based on silicones and at least one another polymer or nonpolymer molecular entity bonded to the silicone chains by nitrogen-containing rings, their preparation process, and their applications. ... 

Structural parameters of the majority of molecules containing Si—O and Si—N bonds differ greatly from those of the carbon analogs. For silicon compounds enhanced values of the SiOSi angle (130-180°) and the tendency to a planar configuration of nitrogen bonds in the NSij grouping are typical Silicon bonds with electro-... 

The preparation1 and properties2 of a great many organo-silicon compounds have been described. However, a relatively small amount of work has been done in the field of silazane chemistry, i.e., the chemistry of compounds which contain at least one silicon-nitrogen bond.3-8 In general, this group of compounds has been found to be extremely sensitive to hydrolysis. The hydrolytic reaction forms the appropriate amine or ammonia and a silanol and/or a siloxane. 

The PCI bond distance in Cl2P(=0)N=C=0 is the same as that in POCI3 to within experimental error, while in Me2NP(=0)Cl2 the bond is longer by 0.04 A (see Table 6). Similar trends are observed in silicon compounds containing two- and three-coordinate nitrogen. 

Asymmetric Mannich reactions provide useful routes for the synthesis of optically active p-amino ketones and esters, which are versatile chiral building blocks for the preparation of many nitrogen-containing biologically important compounds. In recent years, various enantioselective Mannich reactions have been developed. Among them, catalytic enantioselective additions of silicon enolates to imines have been elaborated into one of the most powerful and efhcient asymmetric Mannich-type reactions, primarily because sihcon enolates can be prepared regio- and stereoselectively from various carbonyl compounds. ... 

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