On the protonation of a macrobicyclic cage: an inert tribenzylamine fragment and three robust aminophosphonium units

The protonation of a macrobicyclic cage with four intracyclic nitrogen atoms (one included into a tribenzylamine fragment and the other three into iminophosphorane units) led to tris(aminophosphonium) cations. In the salts, the three anions are situated outside the internal cavity although intercalated within the grooves of its macrobicyclic skeleton. The three aminophosphonium units are remarkably resistant to hydrolysis.