Azaphosphiridine complexes 4a,a′, intermediates in the reaction of P-C₅Me₅ substituted Li–Cl phosphinidenoid complex 2 and C-furyl carbaldimine 3, rearranged selectively to give the novel N,P,C-cage complex 5a. Transient terminal phosphinidene complex 7a was trapped with phenyl acetylene (8) forming the new N,P,C-cage complex 9. DFT calculations provide evidence for a thermally allowed aza-phospha-Cope rearrangement that led to the P-amino substituted phosphinidene complex 7a, which is stabilized by non-covalent interactions in addition to typical through-bond electronic effects.