# Nitride fluoride

Nitride fluorides containing nitride and fluoride ions with the formula NF$^{4-}$. They can be electronically equivalent to a pair of oxide ions O$_2$$^{4-}$. Nitride fluorides were discovered in 1996 by Lavalle et al. They heated diammonium technetium hexafluoride to 300 °C to yield TcNF. Another preparation is to heat a fluoride compound with a nitride compound in a solid state reaction. The fluorimido ion is F-N$^{2-}$ and is found in a rhenium compound.
| name | formula | N:F ratio | system | space group | unit cell (Å) | volume | density | properties |
| dimagnesium fluoride nitride | L-Mg$_2$NF | 1:1 | tetragonal | I4$_1$/amd | a = 4.186, c = 10.042 | | | decompose over 1000 °C to MgF$_2$, Mg gas and N$_2$ |
| | H-Mg$_2$NF | 1:1 | | | | | | H for 1250-1350 °C and 20 kbar |
| | Mg$_3$NF$_3$ | 1:3 | cubic | Pm3m | a = 4.216 | | | light green |
| dicalcium fluoride nitride | Ca$_2$NF | 1:1 | cubic | Fd3m | a = 10.0215, Z = 16 | 1006.46 | 2.987 | light yellow |
| dichromium fluoride nitride | Cr$_2$NF$_3$ | 1:3 | | | | | | dark green |
| dicobalt fluoride nitride | Co$_2$NF | 1:1 | | | | | | |
| dicopper fluoride nitride | Cu$_2$NF | 1:1 | | | | | | |
| | CaMgNF | 1:1 | | | | | | |
| | Fe$_4$N$_3$F$_3$ | 1:1 | | | | | | |
| α | Zn$_2$NF | 1:1 | orthorhombic | P2$_1$2$_1$2$_1$ | a = 5.850, b = 5.892, c = 6.536 | | | band gap 2.7 eV |
| β | Zn$_2$NF | 1:1 | tetragonal | P4$_1$2$_1$2 | a = 5.873, c = 6.532 | | | band gap 2.8 eV |
| | Zn$_9$N$_4$F$_6$ | 2:3 | | | | | | 2 allotropes |
| | Zn$_7$N$_4$F | 4:1 | | | | | | |
| distrontium fluoride nitride | Sr$_2$NF | 1:1 | | Fd3m | a = 10.692, Z = 16 | | | yellowish brown |
| distrontium fluoride nitride | Sr$_2$NF | 1:1 | | Fd3m | a = 10.765, Z = 16 | | | dark red |
| | SrCaNF | 1:1 | cubic | Fd3m | a = 10.340, Z = 16 | 1105.6 | 3.862 | yellow |
| | YNF$_3$ | 1:3 | hexagonal | | a = 5.93, c = 4.79 | | | |
| | Zr$_4$ON$_3$F$_5$ | 3:5 | monoclinic | P112$_1$/b | a = 5.1217, b = 21.513, c = 5.3669, γ = 90.128°, Z = 4 | | | |
| | ZrNF | 1:1 | monoclinic | P21/c | a = 5.227, b = 5.026, c = 5.191, β = 98.98° | | | |
| | NaZr$_3$N$_3$F$_4$ | 3:4 | | P6$_3$/mmc | a = 3.654, c = 18.266 | | | |
| | TcNF | 1:1 | hexagonal | | a = 5.98, c = 4.79 | | | |
| dibarium fluoride nitride | Ba$_2$NF | 1:1 | | Fm3m | a = 5.679, Z = 2 | | | dark violet |
| | LaN$_x$F$_{3(1-x}}$ | x:3(1-x} | cubic | | a = 5.847–5.871 | | | |
| | Ce$_3$NF$_6$ | 1:6 | | | a = 5.8027 | | | F$^−$ conductor |
| | Pr$_3$NF$_6$ | 1:6 | | | a = 5.7723 | | | |
| | Gd$_3$NF$_6$ | 1:6 | cubic | | a = 5.617 | | | |
| | Ce$_2$MnN$_3$F$_{2−δ}$ | | tetragonal | P4/nmm | a = 3.8554, c = 13.088 | | | Nitridomanganate |
| | LiSr$_2$[TaN$_3$]F | 3:1 | orthorhombic | Pbca | a = 10.768, b = 5.591, c = 15.891, Z 8 | 956.7 | | Nitridotantalate, red, air sensitive |
| | ReNF | 1:1 | tetragonal | | a = 5.88, c = 13.00 | | | |
| | Bi$_3$NF$_6$ | 1:6 | orthorhombic | Pbcm | a = 5.8174, b = 5.7018, c = 18.5113, Z = 4 | 614.01 | 8.165 | grey, moisture sensitive |
| | ThNF | 1:1 | rhombohedral | | a = 7.13 | | | |
| | ThN$_x$F$_{4-3x}$ | | tetragonal | | | | | |
| | UN$_x$F$_y$ (UNF) | 1:1 | orthorhombic | | a = 5.632–5.643, b = 5.602–5.610, c = 5.712–5.707 | | | |
| Complexes ||||||||||
| | (AsPh$^+$ $_4$)$_2$[O$_2$(TcNF$_2$)$_2$]$^{2-}$ | 1:2 | | | | | | yellow, O-bridged |
| | Rb$_4$[O(TcNF$_4$)$_2$] | 1:4 | | | | | | orange yellow |
| | Cs$_4$[O(TcNF$_4$)$_2$] | 1:4 | | | | | | orange yellow |
| | H[TcNF$_4$] | 1:4 | | | | | | |
| | (NEt$_4$)$_3$(NH$_4$)[Tc$_4$N$_4$O$_4$F$_8$] | | | | | | | yellow green |
| molecules ||||||||||
| phosphonitrile fluoride (trimer) | (NPF$_2$)$_3$ | 1:2 | rhombohedral | | | | | triple point 27.8 °C; refractive index n$_α$ = 1.388, n$_β$ = 1.419, n$_γ$ = 1.443 |
| phosphonitrile fluoride (tetramer) | (NPF$_2$)$_4$ | 1:2 | monoclinic | | | | | triple point 30.5 °C |
| poly-phosphonitrile fluoride | (NPF$_2$)$_n$ | 1:2 | | | | | | |
| | ReNF$_3$ | 1:3 | | | | | | brown |
| rhenium tetrafluoride nitride | ReNF$_4$ | 1:4 | orthorhombic | | a = 5.64, b = 14.76, c = 4.26 | 354.6 | | yellow, molecular, mp 85 °C |
| fluoroimidorhenium pentafluoride | ReNF$_6$ | 1:6 | monoclinic | | a = 5.298, b = 9.286, c = 9.979, β = 109.4, Z = 4 | 463.2 | 4.507 | orange, molecular, N-F bonded, mp 80 °C |