Classification Nitrate | ||
Xenon nitrate is a transient compound made by reacting xenon difluoride with anhydrous nitric acid. Although xenon dinitrate (Xe(NO3)2) has not been isolated and characterised a related mononitrate: xenon fluoride nitrate has been made and studied.
Contents
Production
Attempted production has used this method:
XeF2 + 2HNO3 → Xe(NO3)2 + 2HF
This reaction made a red-brown solid, that turned blue temporarily as it decomposed spontaneously at 23 °C.
However this decomposes rapidly: Xe(NO3)2 → Xe + O2NOONO2 (an unstable nitrogen peroxide)
However a mixed nitrate definitely exists FXeONO2. This has been called fluoroxenonium nitrate and xenon fluoride nitrate.
This is formed via the reaction:
[FXeOXeFXeF][AsF6] + 2NO2F → FXeONO2 +NO2AsF6.
Purification of FXeONO2 can take place by dissolving in SO2ClF which leaves the nitronium arsenic hexafluoride behind as a solid.
An alternate low yield method to make FXeONO2 is to dissolve xenon difluoride in liquid dinitrogen tetroxide.
XeF2 + NO+ + NO3− → FXeONO2 + NOF at 0 °C
This method is inefficient as not much nitrate ion exists in the liquid and the xenon nitrate decomposes.
Another method claimed to make this substance is:
XeF2 + HNO3 → FXeNO3 + HF
Properties
FXeONO2 is a white crystalline material. 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, b=8.799 Å c=9.415 Å, and non-perpendicular angle β=90.325° and with other axes angles α and γ = 90°. With a molecular weight of 212.3 the crystal has density 3.648. (These measurements at -173 °C.)
The molecule has bond lengths of xenon to fluorine 1.992 Å, xenon to oxygen 2.126 Å, xenon bonded oxygen to nitrogen 1.36 Å, and other nitrate oxygen bonds are 1.199 (cis) and 1.224 Å (trans). The bond angles are FXeO 177.6°, XeON 114.7°, (Xe)ONO 114.5° (cis), other (Xe)ONO 118.4° (trans) and (non-Xe)ONO is 127.1°. 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 halogen nitrates, which indicates a lower bond density for Xe-O bond. N-Ocis bond length is longer than the N-Otrans bond length, the opposite to other halogen nitrates.
FXeONO2 is not particularly stable and slowly breaks down at -78 °C yielding XeF2.N2O4. This happens on a timescale of several days. At 0 °C FXeONO2 has a half life of seven hours decomposing to XeF2.