Xenon fluoride nitrate

This compound is formed via the reaction:[3]

[FXeOXeFXeF][AsF₆] + 2NO₂F → FXeONO₂ + NO₂AsF₆.

Purification of FXeONO₂ can then take place by dissolving in SO₂ClF, which leaves the nitronium arsenic hexafluoride behind as a solid.[3]

An alternate low yield method to make FXeONO₂ is to dissolve xenon difluoride in liquid dinitrogen tetroxide at 0 °C.[3]

XeF₂ + NO⁺ + NO₃⁻ → FXeONO₂ + NOF

This method is inefficient as not much nitrate ion exists in the liquid and the xenon fluoride nitrate decomposes.[3]

Another method claimed to make this substance is:[3]

XeF₂ + HNO₃ → FXeONO₂ + HF

FXeONO₂ is a white crystalline material.[3] The space group of the crystals is P2₁/c, which is monoclinic. The unit cell contains four molecules with a total volume of 386.6 Å³. The unit cell dimensions are a = 4.6663 Å, b = 8.799 Å c = 9.415 Å, with non-perpendicular angle β = 90.325°.[3] With a molecular weight of 212.3, the crystal has density 3.648. (These measurements at -173 °C.)[3] The bond lengths in the molecule are 1.992 Å for Xe–F, 2.126 Å for Xe–O, 1.36 Å for O–NO₂, 1.199 for N–O_cis and 1.224 Å for N–O_trans.[3] The bond angles are 177.6° for F–Xe–O, 114.7° for Xe-O-N, 114.5° for (Xe)O–N–O_cis, 118.4° for (Xe)O–N–O_trans and 127.1° for O_cis–N–O_trans.[3] The bond lengths and angles on the xenon atom are similar to that in FXeOSO₂F and FXeOTeF₅, indicating a polar oxygen bond. The Xe–O–N angle is larger than those in halogen nitrates, which indicates a lower bond density for the Xe–O bond. The N–O_cis bond length is longer than the N–O_trans bond length, opposite to other halogen nitrates.[3]

FXeONO₂ is not particularly stable and slowly breaks down at -78 °C, yielding XeF₂·N₂O₄. This happens on a timescale of several days.[3] At 0 °C, FXeONO₂ has a half life of seven hours, decomposing to XeF₂.[3]