Xenon oxide tetrafluoride

Although uncontrolled reaction of xenon hexafluoride and moisture produces explosive xenon trioxide, controlled action by progressive addition of limited amounts of water vapour with agitation to a frozen solution of the hexafluoride in anhydrous hydrogen fluoride at —196° C to give xenon oxide tetrafluoride or xenon dioxide difluoride is safe [1], Controlled hydrolysis in solution in hydrogen fluoride is, however, described as hazardous [2],... 

Xenon fluorides, 77 323-325 binary, 77 335-336 Xenon-gold cations, 77 332 Xenon halides, 77 323-325 Xenon hexafluoride, 7 7 325, 329 uses for, 7 7 336 Xenon ion lasers, 74 685 Xenon isotopes, in fission reactors, 77 375 Xenon oxide difiuoride, 77 326 Xenon oxide fluorides, 7 7 326 Xenon oxides, 77 325-326 Xenon oxide tetrafluoride, 77 326 Xenon testing, in plastics weathering, 79 584-585... 

Of all the noble gases only xenon has, so far, been shown to yield oxide fluorides. The best known of these, xenon oxide tetrafluoride, was first prepared in 1963. Xe02F2 and XeOF2 are also well characterized and the compounds, XeOjF and Xe02F4 have also been synthesized. The chemistry of these up to 1972-1973 has been authoritatively reviewed (317). 

Electron Distribution in the Xenon Fluorides and Xenon Oxide Tetrafluoride by ESCA and Evidence for Orbital Independence in the Xenon-Fluorine Bonding... 

ThomaSy et al. j Xenon Fluorides and Xenon Oxide Tetrafluoride... 

The Compound XeF XeOFj. Xenon oxide tetrafluoride ) was vacuum distilled on to xenon difluoride(0.67 mmole) contained in a KelF weighing bottle, of lO ml capacity, provided with a KelF valve. Excess XeOF was removed under vacuum with the bottle and its contents at 0°C. The white solid residue, m.p. 29 °C corresponded to an XeOF uptake (0.67 mmole) commensurate with the composition XeFj XeOF. ... 

In view of the instability of the trioxide it is interesting to speculate on the stability of the oxyfluorides. Xenon oxide tetrafluoride should be an exothermic compound since the atomic heat of formation using average bond energies of 32 kcal. and 17 kcal. respectively for Xe-F and Xe-O is —160 kcal. mole-. The combined heat of atomization of four fluorine atoms (4 x 18.3 kcal.) and one oxygen atom (59.2 kcals.), 132.4 kcal., is less than this. Xenon dioxide difluoride, by such considerations, should be endothermic. It is of interest that xenon oxide tetrafluoride is easily made by controlled hydrolysis of xenon hexafluoride and is a thermally stable entity (m.p. —28) whereas xenon dioxide difluoride has been observed only mass spectrometrically < >. 

T. X. Carroll, R. W. Shaw, T. D. Thomas, C. Kindle and N. Bartlett, Electron Distribution in the Xenon Fluorides and Xenon Oxide Tetrafluoride by ESCA and Evidence for Orbital Independence in the Xenon-Fluorine Bonding, J. Am. Chem. Soc. 96 (1974) 1989-1996. 

Shortly after publication of the observations on the synthesis of xenon tetrafluoride, research was initiated with the noble gases in a number of laboratories. Xenon difluoride, xenon hexafluoride, xenon oxide tetrafluoride, and xenon trioxide were synthesized and reasonably well characterized within a rather short time. A number of other compounds have since been isolated, including xenon tetraoxide, a family of perxenates, and a variety of complex fluorides such as XeF2-2SbF5, XeFe BFs, and CsjXeFs. 

Xenon difluoride dissolves in water, yielding a solution which contains undissociated XeFa molecules which have a half-life of about 7 hours at 0°. It eventually hydrolyzes to yield the expected products, xenon, hydrogen fluoride, and oxygen. The hydrolysis reactions of the tetrafluoride and hexafluoride are somewhat more complicated. The addition of the stoichiometric amount of water to the hexafluoride results in the formation of xenon oxide tetrafluoride. Hydrolysis of either fluoride with an excess of water or acid yields in solution a stable xenon(VI) species, which has been shown to be hydrated xenon trioxide. Removal of the excess water leaves xenon trioxide as a solid residue. Inasmuch as this solid is an extremely sensitive explosive, such solutions must be handled with care. 

A shift in the Xe=0 stretching frequency from 923 cm"1 in XeOF4 to 880 cm"1 in solid alkali fluoride-xenon oxide tetrafluoride adducts has been taken to indicate formation of [XeOF5] 146). Raman spectra of NOF XeOF4 show that no appreciable fluoride ion transfer occurs 156). 

How many grams of xenon oxide tetrafluoride, XeOF4, and how many liters of HF at STP could be prepared, assuming complete reaction of 10.5 g of xenon tetrafluoride, XeF4, with a stoichiometric quantity of water according to the equation below ... 

Consider the square pyramidal molecule xenon oxide tetrafluoride, XeOp4, with C4V symmetry. A convenient coordinate system for this molecule is shown on the right. In our convention, each symmetryplane <7v passes through two F atoms, while the aa planes do not. 

All the xenon fluorides react with water to form various products. For example, in aqueous solution, xenon hexafluoride is first hydrolyzed to xenon oxide tetrafluoride, XeOp4, which is further hydrolyzed to xenon trioxide. The reactions are as follows ... 

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