High‐Energy‐Density Materials: Synthesis and Characterization of N 5 + [P(N 3 ) 6 ] − , N 5 + [B(N 3 ) 4 ] − , N 5 + [HF 2 ] − ⋅ n HF, N 5 + [BF 4 ] − , N 5 + [PF 6 ] − , and N 5 + [SO 3 F] −

23 nitrogens and only one phosphorus : The N 5 + ion is combined with energetic anions in the form of N 5 +  [P(N 3 ) 6 ] − and N 5 +  [B(N 3 ) 4 ] − (see scheme), containing 91 and 96 wt %, respectively, of nitrogen. Also, the thermally unstable compound N 5 HF 2 ⋅ n  HF is prepared by metathesis from N 5 SbF 6 and CsHF 2 . Its usefulness as a reagent for the synthesis of new N 5 + salts is demonstrated with the preparation of N 5 PF 6 , N 5 BF 4 , and N 5 SO 3 F.