Krypton tetrafluoride

For many years, krypton was thought to be completely inert. Then, in the early 1960s, it was found to be possible to make certain compounds of the element. English chemist Neil Bardett (1932—2008) found ways to combine noble gases with the most active element of all, fluorine. In 1963, the first krypton compounds were made—krypton difluoride (KrF2) and krypton tetrafluoride (KrF4). Other compounds of krypton have also been made since that time. FFowever, these have no commercial uses. They are only laboratory curiosities. 

Krypton difluoride, 4313 Potassium hexaoxoxenonate-xenon trioxide, 4674 Tetrafluoroammonium hexafluoroxenate, 4386 Xenon difluoride dioxide, 4322 Xenon difluoride oxide, 4319 Xenon difluoride, 4332 Xenon hexafluoride, 4377 Xenon tetrafluoride, 4353 Xenon tetrafluoride oxide, 4346 Xenon tetraoxide, 4863 Xenon trioxide, 4857 Xenon(II) fluoride methanesulfonate, 0443 Xenon(II) fluoride perchlorate, 3977 Xenon(II) fluoride trifluoroacetate, 0634 Xenon(II) fluoride trifluoromethanesulfonate, 0356 Xenon(IV) hydroxide, 4533 Xenon(II) pentafluoroorthoselenate, 4382 Xenon(II) pentafluoroorthotellurate, 4383 Xenon(II) perchlorate, 4110 See Other NON-METAL HALIDES, NON-METAL OXIDES... 

Caesium bromoxenate, 0237 Caesium chloroxenate, 3964 Caesium hydrogen xenate, 4253 Krypton difluoride, 4307 Potassium hexaoxoxenonate—xenon trioxide, 4669 Tetrafluoroammonium hexafluoroxenate, 4380 Xenon difluoride, 4326 Xenon difluoride dioxide, 4316 Xenon difluoride oxide, 4313 Xenon hexafluoride, 4371 Xenon tetrafluoride, 4347 Xenon tetrafluoride oxide, 4340 Xenon tetraoxide, 4857... 

Figure 11.10 Meyer-Overton correlation for volatile general anesthetics in mice. The slope of the regression line is -1.02 and the correlation coefficient, r2 = 0.997. CTF, carbon tetrafluoride NIT, nitrogen ARG, argon PFE, perfluoroethane SHF, sulfur hexafluoride KRY, krypton N02, nitrous oxide ETH, ethylene XEN, xenon DDM, dichlorodifluoromethane CYC, cyclopropane FLU, fluroxene DEE, diethylether ENF, enflurane ISO, isoflurane HAL, halothane CHL, chloroform MOF, methoxyflurane.

Because the noble gases have filled s and p valence orbitals, they are not expected to be chemically reactive. In fact, for many years these elements were called inert gases because of this supposed inability to form any compounds. However, in the early 1960s several compounds of krypton, xenon, and radon were synthesized. For example, a team at the Argonne National Laboratory produced the stable colorless compound xenon tetrafluoride (XeF4). Predict its structure and determine whether it has a dipole moment. 

Like xenon hexafluoride or xenon tetrafluoride, krypton difluoride reacts with water, giving highly explosive hydrolysis products. The best way for disposing of krypton difluoride is to allow it to react with carbon tetrachloride (see caution note under xenon tetrafluoride procedure). 

They were called the inert gases, because it was thought j that they would not react with other elements. Helium and I Neon are not known to com-I bine with other elements. How-j ever, compounds of the higher members of the noble gas I group have been found, this is i due to the presence of d orbit- als (e.g. xenon tetrafluoride and I krypton difluoride). 

This would mean that there are 10 electrons in the valence shell of the Ng atom in xenon difluoride or krypton difluoride and 12 or 14 electrons for xenon tetrafluoride or hexafluoride, and even more for the octafluoroxenate ion, [XeFs] . Since one s and three p orbitals can accommodate only eight electrons, this would require the participation of d orbitals. In fact, the currently favored model uses only s and p atomic orbitals [16]. For example, XeF2 can be constmcted with a three-center-two-electron (3c-2e) bond, like NF5 (Chapter 4, Fig. 4.5) without using d orbitals (Fig. 5.1). Perhaps one should not worry much about which orbitals are involved, because as has been pointed out, bonding is not an observable quantity only bonding distancies and electron density are amenable to observation although... 

The reaction of xenon with a large excess of O2F2 at 155 K gives XeF2 almost quantitatively. No reaction occurs with krypton up to 195 K [16]. Radon or xenon di- and tetrafluorides were obtained from O2F2 and xenon or radon, respectively, below 173 K [17]. 

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