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The NMR spectra (35Cl, 79Br, 81Br, 127I and 17O) of the tetrahedral perhalate anions XO4− (X Cl, Br and I) were compared for the first time in acetonitrile solution, a medium in which the resonances are relatively sharp and in which no oxygen exchange occurs. Relaxation studies of the quadrupolar nuclei in these solutions at 24°C are reported and show that excellent spectra may be obtained at 0.1 M concentration; thus the observation of separate resonances for Cl 16O4− and Cl 18O 16O3− represents the first reported instance of a 35Cl secondary isotopic shift [1 Δ 35Cl(18.16O) = -0.090 ppm]. Enrichment with 17O of all three ions was carried out and the 1J(127I, 17O) coupling constant (489 Hz) has been observed for the first time. The chemical shifts and coupling constants are discussed, especially in connection with the anomalous properties of the perbromate ion. Halogen chemical shifts for BrO3F, IF7 and IF6+ AsF6− are reported for the first time.

Oxidation Reactions with HOF and Adducts of HOF and HF with Acetonitrile In acetonitrile solution HOF oxides CF3SSCF3 via CF3S(O)nSCF3 (n = 1, 2) to yield [CF3S(O)2]2O. Analogously, CF3Se(O)OH and CF3SeX (X = Cl, Br) are oxidized via CF3Se(VI) intermediates to provide finally [CF3Se(O)2]2O. With CH3CN at low temperatures HOF and HF form 1:1 adducts, whose structures have been elucidated by low-temperature X-ray structure analysis. Additional proof for the formation of CH3CN · HF in the liquid phase is provided.

Methyl hypofluorite (CH 3 OF) has been prepared by the reaction of elemental fluorine with methanol in acetonitrile or propionitrile at low temperature. It was removed from the reaction mixture in a stream of nitrogen and purified by fractional distillation. The compound is moderately long-lived, although the liquid has exploded upon rapid warming. The liquid compound has a freezing point of about −142°C, and vapor pressure measurements indicate a normal boiling point of −32.6±0.9°C and an enthalpy of vaporization of 23.37±0.26 kJ/mol. The infrared spectrum of the vapor is consistent with the molecule being isostructural with CH 3 OH and CF 3 OF. The compound has also been characterized by mass spectrometry and by 1 H, 19 F, and 13 C NMR spectrometries. This novel reagent adds across various double bonds to form the corresponding fluoro methoxy adducts, which are not easily accessible by other methods

Trifluoromethanesulfonyl hypofluorite (CF[sub 3]SO[sub 2]OF) has been synthesized by the reaction of fluorosulfuryl hypofluorite (FSO[sub 2]OF) with cesium trifluoromethanesulfonate. It is the first compound in which a sulfur atom is bonded both to carbon and to an O-F moiety. The compound has a melting point of -87 [plus minus] 2[degrees]C and an extrapolated boiling point of 0 [plus minus] 1[degrees]C. The [sup 19]F NMR spectrum of the compound in CFCl[sub 3] at -80[degrees]C shows a CF[sub 3] doublet at -71 ppm and a broad OF singlet at +238 ppm. From the latter can be deduced an O-F bond energy of about 145 kJ/mol, comparable to that of FSO[sub 2]OF. The compound hydrolyses in base to give a mixture of O[sub 2] and CF[sub 4], along with (presumably) sulfate and trifluoromethanesulfonate. It decomposes thermally in the presence of CsF to yield principally CF[sub 3]SO[sub 2]F and OF[sub 2] along with (presumably) cesium trifluoromethanesulfonate. 14 refs., 1 tab.

The strong oxidant produced by the reaction of elemental fluorine with acetonitrile containing ca. 10% water has been shown to be hypofluorous acid, HOF, which is stabilized by complexing to the solvent. The reaction represents a new and convenient method of preparing and handling HOF, a unique oxygenating reagent. The presence of acetonitrile results in subtle but significant changes in the chemical behavior of the HOF. Vibrational and NMR spectroscopic studies of the solutions resulting from this reaction, as well as of solutions prepared by dissolving neat HOF in dry acetonitrile, have shown that the complex is a 1:1 hydrogen-bridged entity, in which the HOF proton is most likely bonded to the nitrogen atom of the nitrile. The 19 F NMR data indicate that the complexation reaction has an equilibrium constant of ca. 3 at room temperature, and that the enthalpy of formation of the complex is −14.3 ± 0.5 kJ mol −1 . The success of this method of synthesizing hypofluorous acid is a consequence of the very slow reaction between HOF and low concentrations of water in acetonitrile. This reaction accelerates drastically as the water content increases. As the solution composition approaches 100% water, the rate constant appears to approach a limit of about 0.7 s −1 at 25 °C, which may be the actual rate of reaction of HOF with the water.

tert-Butyl hypofluorite ((CH[sub 3])[sub 3]COF) can be synthesized by the low-temperature reaction of elemental fluorine with tert-butyl alcohol dissolved in propionitrile or acetonitrile. The isolated compound, which melts around -94[degrees]C and has an extrapolated boiling point of about +40[degrees]C, has been characterized by mass, NMR, and IR spectrometry. The [sup 19]F NMR shift of +67 ppm lies between the corresponding shifts of HOF and CH[sub 3]OF and implies a rather high O-F bond energy. Although sterically crowded, tert-butyl hypofluorite adds to olefins to form [beta]-fluoro-tert-butoxy compounds. Addition is mainly in an anti mode, and the regioselectivity corresponds to the action of a hitherto unknown tert-butoxylium electrophile. Also formed are adducts containing F and CH[sub 2]CN, the latter deriving from the acetonitrile solvent. 19 refs., 1 tab.

The Raman spectra of solid HOF, DOF, and an HOF/DOF mixture have been measured. Two of the three internal vibrations (the O–F and O–H stretches) were seen, and they coincide with the bands previously found in the infrared spectrum of the solid. Six low frequency intermolecular bands found in the infrared have been interpreted in terms of a hydrogen‐bonded structure consisting of planar zigzag chains, similar to the chains that constitute the structure of solid HF.

The gas-phase reaction of mercury with ammonium iodide is the basis of at least one scheme for the thermochemical production of hydrogen. We have studied the reactions Hg + 2HI ..-->.. HgI/sub 2/ + H/sub 2/ and Hg + 2NH/sub 4/I ..-->.. HgI/sub 2/ + H/sub 2/ + 2NH/sub 3/ in the gas phase for 623 to 693 K. Under our conditions NH/sub 4/I is completely dissociated to NH/sub 3/ and HI. The reactions were followed by spectrophotometrically monitoring the buildup of the product, HgI/sub 2/. In the absence of NH/sub 3/ and with approximately 20-fold excess of HI (10/sup -3/ M equal to or less than (HI) equal to or less than 10/sup -2/ M), the rate of appearance of HgI/sub 2/ is given by d(HgI/sub 2/)/dt = k/sub 4/(Hg)(HI). With excess Hg, however, the rate follows the expression d(HgI/sub 2/)/dt = k/sub 5/(Hg)(HI)/sup 2/. Introduction of NH/sub 3/ into the system increases the rate substantially. In the presence of ammonia at concentrations comparable to those of the Hg and HI, the rate law assumes the form d(HgI/sub 2/)/dt = k/sub 3/(Hg)(HI)/sup 2/(NH/sub 3/). At 663 K k/sub 4/, k/sub 5/, and k/sub 3/ have the values 3.7 Lmore » mol/sup -1/ min/sup -1/, 590 L/sup 2/ mol/sup -2/ min/sup -1/, and 2.2 x 10/sup 6/ L/sup 3/ mol/sup -3/ min/sup -1/, respectively. Increasing the surface-to-volume ratio has no discernible effect on the reaction rate. The constant k/sub 3/ has a negative temperature dependence, which corresponds to an activation energy of -34 kJ/mol. The reaction in the presence of ammonia is interpreted in terms of a preequilibrium to form a complex HI . Hg . NH/sub 3/. 4 tables, 5 figures.« less

Aus Octaethylporphyrin erhalt man mit HOF oder Peroxy- essigsaure in Trichlormethan Octaethylporphyrin-N-oxid in 64%iger Ausbeute.

Stopped-flow spectrophotometry was used to study the oxidation of plutonium(III) to plutonium(IV) is 1 M HClO{sub 4} by XeF{sub 2} and by the fluoroxysulfate ion, SO{sub 4}F{sup {minus}}. In both reactions, 2 mol of Pu(III) is oxidized per 1 mol of oxidant consumed, and neither Pu(V) or Pu(VI) appears to be formed either as an intermediate or as an initial product, although an excess of XeF{sub 2} does slowly oxidize the Pu(IV) product to Pu(VI). At 2{degree}C the reactions have respective bimolecular rate constants of 1160 {plus minus} 70 and 120 {plus minus} 9 M{sup {minus}1} s{sup {minus}1}, expressed in terms of -d(Pu(III))/dt. Over the temperature range 2-24{degree}C, the activation parameters for the XeF{sub 2} reaction are {Delta}H{sup {double dagger}} = 39.5 {plus minus} 8.6 kJ/mol and {Delta}S{sup {double dagger}} = {minus}48.3 {plus minus} 29 J/(mol K), while those for the SO{sub 4}F{sup {minus}} reaction are {Delta}H{sub {double dagger}} = 30.8 {plus minus} 2.3 kJ/mol and {Delta}S{sup {double dagger}} = {minus}98.5 {plus minus} 7.8 J/(mol K). Mechanisms are postulated that invoke a sequence of two one-electron-oxidation steps. 24 refs., 2 tabs.

Aus kalorimetrischen Messungen wird die Hydrolyseenthalpie von BrO3F in HF und HBrO4 ermittelt.

HOF cristallise avec le groupe d'espace P2 1 2 1 2 1 . Affinement de la structure jusqu'a 0,027