1,1′,4,5-Tetra­hydro­tri­spiro­[1,3,2-di­aza­phosphole-2,2′-[1,3,5,2,4,6]tri­aza­triphosphinine-4′,6′′-dibenzo[d,f][1,3,2]dioxaphosphepine-6′,6′′′-dibenzo[d,f][1,3,2]dioxaphosphepine] acetone monosolvate

The title compound, C₂₆H₂₂N₅O₄P₃·C₃H₆O, has been achieved in a two-step synthesis that does not require chromatography. This mol­ecule contains a seven-membered spiro­cyclic ring at two P-atom positions and a five-membered ring containing new P—N bonds at the other P-atom position. Endocyclic torsion angles about the central biphenyl C—C bonds are −41.5 (3) and −44.4 (3)°, and P—N bonds of the central P₃N₃ ring are within the range 1.5665 (17)–1.6171 (17) Å, while the P—O distances are in the range 1.5940 (14)–1.6041 (14) Å. One N—H group makes an inter­molecular N—H...N hydrogen bond, forming centrosymmetric dimers, while the other N—H group makes an N—H...O hydrogen bond to the acetone solvent mol­ecule. The crystal was a two-component non-merohedral twin with ratio 0.811/0.189.