Three identical bidentate ligands complexed with penta- and hexa-co-ordinate phosphorus: stereospecificity of the PV→ PVI transformation

Abstract

The substitution of bidentate ligands for chlorine, in benzene solution, for phosphorus pentachloride, leads to the equilibrated phosphoranes (4)⇌(5). Because of its insolubility the bridged bispentaoxyphosphorane (4a) has been isolated. The addition of a weak base (dimethylformamide) in this system shows the existence of the (5)⇌(6) equilibrium. A stereospecific transformation P^V→ P^VI is obtained by the addition of an optically active strong base, (–)-brucine.