1,2λ5,5λ5-azadiphospholium structures

The reactions of bromophenylacetylene with the diphenylphosphino amines (Ph₂P)₂NH and (Ph₂P)₃N result in the 1,1,3,3,4-pentaphenyl-1,2,5-azadiphospholium bromide ( 5 ) and its 4-diphenylphosphino derivative ( 7 ). Their X-ray structure analyses show planar rings for the cations. The small endocyclic angle at the nitrogen ring member is associated with PN bonds that are longer than in the acyclic cation (Ph₃P)₂N⁺. The data fit to a negative linear relationship of PN bond lengths and PNP bond angles. © 1997 John Wiley & Sons, Inc.