Polynitrogen chemistry. Synthesis, characterization, and crystal structureof surprisingly stable fluoroantimonate salts of N-5(+)

The new N-5(+) salt, N5+SbF6-, was prepared from N2F+SbF6- and HN3 in anhyd rous HF solution. The white solid is surprisingly stable, decomposing only at 70 degreesC, and is relatively insensitive to impact. Its vibrational sp ectrum exhibits all nine fundamentals with frequencies that are in excellen t agreement with the theoretical calculations for a five-atomic V-shaped io n of C-2v. symmetry, The N5+Sb2F11- salt was also prepared, and its crystal structure was determined. The geometry previously predicted for free gaseo us N-5(+) from theoretical calculations was confirmed within experimental e rror. The Sb2F11- anions exhibit an unusual geometry with eclipsed SbF4 gro ups due to interionic bridging with the N-5(+) cations. The N-5(+) cation i s a powerful one-electron oxidizer. It readily oxidizes NO, NO2, and Br-2 b ut fails to oxidize Cl-2, Xe, or O-2.