Compounds Containing Penta- and Hexa-Coordinated Organic Silicon

11 Compounds Containing Penta- and Hexa-Coordinated Organic Silicon 

The silatranes are examples of intramolecular complexes which include bound nitrogen and pentacoordinate silicon. Structural examination of these complexes shows [519] that the silatrane molecule is a distorted bipyramid, in which three oxygen atoms occupy the equatorial plane, while the organic groups and the nitrogen atom are on the axis. 

Organosilanes can also form a complex bond with oxygen, which results in an intramolecular complex with a pentacoordinated silicon, e.g. in the preparation of 3-benzoyl-6-phenyl-2,2.4,4-tetramethyl-2,4-disila-l,3,5-oxadiazine [520] (Eq. 3211)  

Structural studies indicate that aroyloxy methyltrifluorosilanes are similarly pen-tacoordinated [521]. 

Upon reaction with powerful bidentate nitrogen bases, e.g. 2,2 -bipyridyl or 1,10-phenanthroline, the halogen atoms are removed (as anions) from halogen mono- and diorganosilane, leaving these as hexacoordinated silicon cations, e.g. in the preparation of bis(2,2 -bipyridylyl)halo-organosilanonium iodide [522] (Eq. 3.278)  

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