Polynitrogen chemistry. Synthesis, characterization, and crystal structure of surprisingly stable fluoroantimonate salts of N5+

The new N5+ salt, N5+SbF6-, was prepared from N2F+SbF6- and HN3 in anhydrous HF solution. The white solid is surprisingly stable, decomposing only at 70 °C, and is relatively insensitive to impact. Its vibrational spectrum exhibits all nine fundamentals with frequencies that are in excellent agreement with the theoretical calculations for a five-atomic V-shaped ion of C2v symmetry. The N5+Sb2F11- salt was also prepared, and its crystal structure was determined. The geometry previously predicted for free gaseous N5+ from theoretical calculations was confirmed within experimental error. The Sb2F11- anions exhibit an unusual geometry with eclipsed SbF4 groups due to interionic bridging with the N5+ cations. The N5+ cation is a powerful one-electron oxidizer. It readily oxidizes NO, NO2, and Br2 but fails to oxidize Cl2, Xe, or O2.