Fluoro-nitrogen Cations.

The crystal structures of [NH 3 F] + [CF 3 SO 3 ] - , [NH 2 F 2 ] + [SbF 6 ] - , and [N 2 F 3 ] + [Sb 3 F 16 ] - have been determined, representing the first structural characterizations of these simple fluoro-nitrogen cations. The influences of the hybridization of the central nitrogen atom and of the number of fluorine substituents on the N-F bond lengths are evaluated for the series N 2 F + , N 2 F 3 + , NF 2 O + , NH 3 F + , NH 2 F 2 + , and NF 4 + . It is shown that the N-F bond length decreases from 1.40 Å to 1.26 Å with increasing fluorine substitution and increasing s-character of the nitrogen atom, and that unusual N-F bond lengths reported in the previous literature are caused by disorder problems.