New macrobicyclic triphosphazides and triphosphazenes formed by self-assembly of tripodal triazides with triphosphanes

The self-assembly of tris(3-azidobenzyl)amines with 1,1,1-tris(diphenylphosphino)methyl]ethane via tripod-tripod coupling proceeds successfully to give chiral macrobicyclic triphosphazides. The heating of these macrobicyclic cages induces a remarkable stepwise triple extrusion of molecular nitrogen to afford tri-λ⁵-phosphazenes, which preserved the chiral, propeller-like topology of their precursors. The replacement of one benzylic arm by an ortho-phenethylic or propylenic one still allows the success of the self-assembly. However, the quaternization of the pivotal nitrogen atom of the triamine in the form of N-oxide prevented its coupling with the triphosphane.