Aluminum pentavalent

A mechanism for the GTPase activity has been proposed from the crystal structure of aluminum fluoride (A1F4 ) complex with transducin-a.69 Aluminum fluoride activates transducin-a- GDP by binding with a geometry resembling a pentavalent intermediate for GTP hydrolysis. 

In many ways the phosphates provide the richest field for CBC s (chemically bonded ceramics) because of the P—O bond strengths and the coordination demands of pentavalent phosphorus. Among silicates, room temperature hydration reactions seem to be possible only with Ca-compounds the magnesium and aluminum anhydrous silicates phases simply do not react. This book documents for the reader the wide application of these separate chemistries as true chemically bonded ceramics. 

Recently, hydrocyanation and cyanosilylation reactions with other type of chiral aluminum complexes were reported. In 1999, Shibasaki and Kanai reported enantioselective cyanosilylation of aldehydes catalyzed by Lewis acid-Lewis base bifunctional catalyst (64a) [56, 57]. In this catalyst, aluminum center works as a Lewis acid to activate the carbonyl group, and the oxygen atom of the phosphine oxide works as a Lewis base to activate TMSCN. Asymmetric induction was explained by the proposed transition state model having the external phosphine oxide coordination to aluminum center, thus giving rise to pentavalent aluminum... 

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