Atrane

of the allyl silatrane molecule Various atranes are named depending on the central element, e.g. "silatrane" (E = silicon); "boratrane" (E = boron); "phosphatrane" (E = phosphorus), stannatrane (E = tin), etc. It is also proposed that when Y = nitrogen, the prefix "aza" be inserted before element + "atrane" (azasilatrane, for example) because atranes wherein E = silicon and Y = oxygen have been referred to as just "silatranes". Bis-atranes are two atrane cages that are fused end-to-end, sharing the same Lewis-acid donor atom in two co-axial dative interations. == Structure and properties ==

Silatranes exhibit unusual properties, as the transannular coordinate bond in atranes can be stretched (quasiatranes) and even broken (proatranes). The strength (and multiplicity) of the central bond depends on the stereoelectronic properties of the surrounding ligands, the electronegativity of the participating atoms, and the size of the rings. A strong driving force for the formation of the central bond is relief of ring strain from the otherwise-formed 8-membered rings. Proazaphosphatrane is a very strong non-ionic base and is utilized in various types of organic synthesis as an efficient catalyst. ==See also==