- Synthesis of water and molecular oxygen highly enriched in 17O and 18O isotopes from carbon oxides
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The reaction of carbon oxides and hydrogen in the presence of the Raney nickel catalyst has been used for water synthesis. A procedure has been developed for the recovery and collection of the synthesized water with minimal losses and without deteriorating the 17O or 18O isotope enrichment as compared to the initial CO2 and CO. The recovery of oxygen with high concentrations of 17O and 18O isotopes is based on the reaction of xenon difluoride with water. The yield based on oxygen achieves 99% without reduction of isotope enrichment, which is confirmed by mass-spectral measurements of oxygen isotope concentrations in the initial reagents and final reaction products. Pleiades Publishing, Ltd., 2011.
- Artyukhov,Kravets,Artyukhov,Babichev,Ryzhkov
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- Largest perfluorometallate [Ti10F45]5- oligomer and polymeric ([Ti3F13]-)∞ and ([TiF5]-)∞ anions prepared as [XeF5]+ salts
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Reactions between XeF2, TiF4 and UV-irradiated elemental F2 in anhydrous HF yielded XeF5TiF5 (XeF6·TiF4), [XeF5]5[Ti10F45] (XeF6·2TiF4), and [XeF5][Ti3F13] (XeF6·3TiF4) upon crystallization. [XeF5]5[Ti10F45] crystallizes in two crystal modifications at low (α-phase, 150 K) and ambient (β-phase, 296 K) temperatures. The crystal structure determination of [XeF5]5[Ti10F45] reveals the largest known discrete decameric [Ti10F45]5- anion built from ten TiF6 octahedra, sharing vertices, in the shape of a double-star. [XeF5]+ cations are completely ordered in the α-phase, while one of three crystallographically unique [XeF5]+ cations is two-fold disordered in the β-phase. The anionic part of [XeF5][Ti3F13] is built from tetrameric Ti4F20 and octameric Ti8F36 units sharing vertices and alternatively linked into ([Ti3F13]-)∞ columns. The charge balance is maintained by [XeF5]+ cations which form secondary Xe?F contacts with fluorine atoms of ([Ti3F13]-)∞ groups. The main structural feature of XeF5TiF5 is an infinite chain of distorted TiF6 octahedra joined by cis vertices.
- Mazej, Zoran,Goreshnik, Evgeny A.
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- Synthesis, raman spectra and crystal structures of [Cu(XeF 2)n](SbF6)2 (n = 2, 4)
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Pure [Cu(XeF2)2](SbF6)2 was prepared by the reaction of Cu(SbF6)2 with a stoichiometric amount of XeF2 in anhydrous hydrogen fluoride (aHF) at ambient temperature. The reaction between Cu(SbF6)2 and XeF2 (1:4 molar ratio) in aHF yielded [Cu(XeF2) 4](SbF6)2 contaminated with traces of Xe 2F3SbF6 and CuF2. The 6-fold coordination of Cu2+ in [Cu(XeF2)2](SbF 6)2 includes two fluorine atoms from two XeF2 ligands and four fluorine atoms provided by four [SbF6]- anions. The neighboring [Cu(XeF2)2]2+ moieties are connected via two [SbF6] units, with the bridging fluorine atoms in cis positions, into infinite -[Cu(η1-XeF2) 2]-(cis-η2-SbF6)2- [Cu(η1-XeF2)2]- chains. Because of the high electron affinity of Cu2+, coordinated XeF2 shows the highest distortion (Xe-Fb = 210.2(5) pm, Xe-Ft = 190.6(5) pm) observed so far among all known [Mx+(XeF2) n](A)x (A = BF4, PF6, etc.) complexes. The four equatorial coordination sites of the Cu2+ ion in [Cu(XeF2)4](SbF6)2 are occupied by four XeF2 ligands. Two fluorine atoms belonging to two [SbF 6] units complete the Cu2+ coordination environment. The neighboring [Cu(XeF2)4]2+ species are linked via one [SbF6] unit, with bridging fluorine atoms in trans positions, into linear infinite -[Cu(η1-XeF2) 4]-(trans-η2-SbF6)-[Cu(η1- XeF2)4]- chains. To compensate for the remaining positive charge, crystallographically independent [SbF6]- anions are located between the chains and are fixed in the crystal space by weak Xe...F(Sb) interactions.
- Mazej, Zoran,Goreshnik, Evgeny
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- New Coordination Compounds of Cd(AsF6)2 with HF and XeF2
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Two new coordination compounds of cadmium with HF and XeF2 as ligands have been synthesized. Solid white [Cd(HF)](AsF6) 2 is obtained from an anhydrous HF (aHF) solution of Cd(AsF 6)2. It crystallizes in a monoclinic P21/c space group with a = 9.4687(14) A, b = 9.2724(11) A, c = 10.5503(18) A, β = 104.887(7)°, and Z = 4. The coordination sphere of Cd consists of 7 + 2 fluorine atoms, which are in a capped trigonal-prismatic arrangement. The reaction between Cd(AsF6)2 and XeF 2 in aHF yields a solid white product at room temperature having the composition [Cd(XeF2)4](AsF6)2 after the excess XeF2 and solvent have been removed under dynamic vacuum. [Cd(XeF2)4](AsF6)2 crystallizes in the orthorhombic space group P21212 1, with a = 8.6482(6) A, b = 13.5555(11) A, c = 16.6312(14) A, and Z = 4. The coordination sphere of Cd consists of eight fluorine atoms, which are at the corners of a trigonal prism with two capped side faces.
- Tavcar, Gasper,Benkic, Primoz,Zemva, Boris
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- Chemical and physical properties of some xenon compounds
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Useful preparative reactions for several xenon compounds can be systematized as acid-base chemistry. The hydrolysis of XeF4 and ammonolysis of XeF6 have been investigated. The melting point of XeO4 and the melting point an
- Huston, John L.
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- Synthesis and characterisation of [XeF5]3[Ti 4F19] containing a discrete [Ti4F 19]3- anion
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The complex [XeF5]3[Ti4F19] was prepared by reaction of XeF2, TiF4 and UV-irradiated elemental fluorine in anhydrous hydrogen fluoride as the solvent. The crystal structure of [XeF5/s
- Mazej, Zoran,Goreshnik, Evgeny
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- [Mg(XeF2)n](AsF6)2 (n = 4, 2): First Compounds of Magnesium with XeF2
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The reaction between Mg(AsF6)2 and XeF2 in anhydrous HF (aHF) at room temperature yields two compounds with XeF 2 bonded directly to the Mg2+ cation: [Mg(XeF 2)4](AsF6)2; [Mg(XeF 2)2](AsF6)2. The 1:4 compound is obtained with excess XeF2 while the 1:2 compound is prepared from stoichiometric amounts of Mg(AsF6)2 and XeF2. [Mg(XeF2)4](AsF6)2 crystallizes in an orthorhombic crystal system, space group P21212 1, with a = 8.698(15) A, b = 14.517(15) A, c = 15.344(16) A, V = 1937(4) A3, and Z = 4. The octahedral coordination sphere of Mg consists of one fluorine atom from each of the four XeF2 molecules and two fluorine atoms from the two AsF6 units. [Mg(XeF2)2](AsF6)2 crystallizes in the orthorhombic crystal system, space group Pbam, with a = 8.9767(10) A, b = 15.1687(18) A, c = 5.3202(6) A, V = 724.42(14) A, and Z = 2. The octahedral coordination sphere consists of two fluorine atoms, one from each of the two XeF2 molecules and four fluorine atoms from the four bridging AsF6 units.
- Tramsek, Melita,Benkic, Primoz,Zemva, Boris
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- X-ray crystal structures of [XeF][MF6] (M = As, Sb, Bi), [XeF][M2F11] (M = Sb, Bi) and estimated thermochemical data and predicted stabilities for noble-gas fluorocation salts using volume-based thermodynamics
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The crystal structures of the xenon(II) salts, [XeF][SbF6], [XeF][BiF6], and [XeF][Bi2F11], have been determined for the first time, and those of XeF2, [XeF][AsF 6], [XeF][Sb2F11], and [XeF3] [Sb2F11] have been redetermined with greater precision at -173 °C. The Bi2F11- anion, which has a structure analogous to those of the As2F11- and Sb2F11- anions, has been structurally characterized by single crystal X-ray diffraction for the first time as its XeF+ salt. The fluorine bridge between the bismuth atoms is asymmetric with Bi...Fb bond lengths of 2.092(6) and 2.195(6) A and a Bi...Fb′...Bi bridge bond angle of 145.3(3)o. The XeF+ cations interact with their anions by means of Xe...Fb...M bridges. Consequently, the solid-state Raman spectra of [XeF][MF6] (M = As, Sb, Bi) were modeled as the gas-phase ion pairs and assigned with the aid of quantum-chemical calculations. Relationships among the terminal Xe-Ft and bridge Xe...F b bond lengths and stretching frequencies and the gas-phase fluoride ion affinities of the parent Lewis acid that the anion is derived from are considered. The analogous krypton ion pairs, [KrF][MF6] (M = As, Sb, Bi) were also calculated and compared with their previously published X-ray crystal structures. The calculated cation-anion charge separations indicate that the [XeF][MF6] salts are more ionic than their krypton analogues and that XeF2 is a stronger fluoride ion donor than KrF2. The lattice energies, standard enthalpies, and free energies of formation for salts containing the NgF+, Ng2F3+, XeF3+, XeF5+, Xe2F 11+, and XeOF3+ (Ng = Ar, Kr, Xe) cations were estimated using volume-based thermodynamics (VBT) based on crystallographic and estimated ion volumes. These estimated parameters were then used to predict the stabilities of noble-gas salts. VBT is used to examine and predict the stabilities of, inter alia, the salts [XeFm][Sb nF5n+1] and [XeFm][AsnF 5n+1] (m = 1, 3; n = 1, 2). VBT also confirms that XeF+ salts are stable toward redox decomposition to Ng, F2, and MF 5 (M = As, Sb), whereas the isolable krypton compounds and the unknown ArF+ salts are predicted to be unstable by VBT with the ArF+ salts being the least stable.
- Elliott, Hugh St. A.,Lehmann, John F.,Mercier, Helene P.A.,Jenkins, H. Donald Brooke,Schrobilgen, Gary J.
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- Single-crystal structure determination of NO2SbF6, XeF5SbF6 and XeF5Sb2F11
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NO2SbF6 crystalizes at 150 K in the orthorhombic Cmmm space group (No. 65) with a = 6.8119(7) ?, b = 7.3517(7) ?, c = 5.5665(5) ?, V = 278.77(5) ?3, and Z = 2. Its crystal structure exhibits a different packing of the [NO2]+ and [SbF6]- ions than in the known crystal structure of NO2AsF6. The XeF5SbF6 compound is orthorhombic at 150 K, space group Pnma (No. 62), with a = 16.7159(6) ?, b = 8.1093(3) ?, c = 5.7576(2) ?, V = 780.47(5) ?3, Z = 4, and it is isotypic with the known XeF5MF6 crystal structures of M = Nb, Ru, and Pt. The unit cell of XeF5Sb2F11 is triclinic at 200 K, P1ˉ space group (No. 2), with a = 8.5223(8) ?, b = 8.5582(8) ?, c = 9.2012(8) ?, α = 68.799(8)°, β = 74.897(8)°, γ = 76.252(8)°, V = 596.35(10) ?3 and Z = 2. Each [XeF5]+ cation has four interactions with the three [Sb2F11]- anions.
- Mazej, Zoran,Goreshnik, Evgeny A.
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- Metal(II) hexafluorophosphates(V) (M = Sr, Pb) containing XeF 2-coordinated metal ions [M(XeF2)3](PF 6)2, [Pb3(XeF2)11] (PF6)6, and [Sr3(XeF2) 10](PF6)6
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From the system MF2/PF5/XeF2/anhydrous hydrogen fluoride (aHF), four compounds [Sr(XeF2)3] (PF6)2, [Pb(XeF2)3]-(PF 6)2, [Sr3(XeF2)10](PF6)6, and [Pb3(XeF2)11](PF6)6 were isolated and characterized by Raman spectroscopy and X-ray single-crystal diffraction. The [M(XeF2)3](PF6)2 (M = Sr, Pb) compounds are isostructural with the previously reported [Sr(XeF 2)3](AsF6)2. The structure of [Sr3(XeF2)10](PF6)6 (space group C2/c, a = 11.778(6) A, b = 12.497-(6) A, c = 34.60(2) A, β = 95.574(4)°, V = 5069(4) A3, Z = 4) contains two crystallographically independent metal centers with a coordination number of 10 and rather unusual coordination spheres in the shape of tetracapped trigonal prisms. The bridging XeF2 molecules and one bridging PF6- anion, which connect the metal centers, form complicated 3D structures. The structure of [Pb3(XeF 2)11](PF6)6 (space group C2/m; a = 13.01(3) A, b = 11.437(4) A, c = 18.487(7) A, β = 104.374(9)°, V = 2665(6) A3, Z = 2) consists of a 3D network of the general formula {[Pb3(XeF2) 10](PF6)6}n and a noncoordinated XeF2 molecule fixed in the crystal structure only by weak electrostatic interactions. This structure also contains two crystallographically independent Pb atoms. One of them possesses a unique homoleptic environment built up by eight F atoms from eight XeF2 molecules in the shape of a cube, whereas the second Pb atom with a coordination number of 9 adopts the shape of a tricapped trigonal prism common for lead compounds. [Pb3(XeF2)11](PF6) 6 and [Sr3(XeF2)10](PF 6)6 are formed when an excess of XeF2 is used during the process of the crystallization of [M(XeF2) 3](PF6)2 from their aHF solutions.
- Bunic, Tina,Tramsek, Melita,Goreshnik, Evgeny,Tavcar, Gasper,Zemva, Boris
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- Role of XeF as an Intermediate in the Photochemical Synthesis of XeF2 in Flash-Photolyzed Xe/Ar/F2 Mixtures
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The fluorine in Xe/F2 and Xe/Ar/F2 mixtures was photodissociated, and the resulting transient species were monitored by photographic and photoelectric UV kinetic absorption spectroscopy and by laser fluorescence.The number density equilibrium constant for
- Messing, Itzhak,Smith, Allan L.
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- Xenon(IV)-carbon bond of [C6F5XeF2]+; Structural characterization and bonding of [C6F5XeF2][BF4], [C6F5XeF2][BF4]·2HF, and [C6F5XeF2][BF4]· n NCCH 3 (n = 1, 2); And the fluorinating properties of [C6F5XeF2][BF4]
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The [C6F5XeF2]+ cation is the only example of a XeIV-C bond, which had only been previously characterized as its [BF4]- salt in solution by multi-NMR spectroscopy. The [BF4]- salt and its new CH3CN and HF solvates, [C6F5XeF2][BF4]·1.5CH3CN and [C6F5XeF2][BF4]·2HF, have now been synthesized and fully characterized in the solid state by lowerature, single-crystal X-ray diffraction and Raman spectroscopy. Crystalline [C6F5XeF2][BF4] and [C6F5XeF2][BF4]·1.5CH3CN were obtained from CH3CN/CH2Cl2 solvent mixtures, and [C6F5XeF2][BF4]·2HF was obtained from anhydrous HF (aHF), where [C6F5XeF2][BF4]·1.5CH3CN is comprised of an equimolar mixture of [C6F5XeF2][BF4]·CH3CN and [C6F5XeF2][BF4]·2CH3CN. The crystal structures show that the [C6F5XeF2]+ cation has two short contacts with the F atoms of [BF4]- or with the F or N atoms of the solvent molecules, HF and CH3CN. The lowerature solid-state Raman spectra of [C6F5XeF2][BF4] and C6F5IF2 were assigned with the aid of quantum-chemical calculations. The bonding in [C6F5XeF2]+, C6F5IF2, [C6F5XeF2][BF4], [C6F5XeF2][BF4]·CH3CN, [C6F5XeF2][BF4]·2CH3CN, and [C6F5XeF2][BF4]·2HF was assessed with the aid of natural bond orbital analyses and molecular orbital calculations. The 129Xe, 19F, and 11B NMR spectra of [C6F5XeF2][BF4] in aHF are reported and compared with the 19F NMR spectrum of C6F5IF2, and all previously unreported J(129Xe-19F) and J(19F-19F) couplings were determined. The long-term solution stabilities of [C6F5XeF2][BF4] were investigated by 19F NMR spectroscopy and the oxidative fluorinating properties of [C6F5XeF2][BF4] were demonstrated by studies of its reactivity with K[C6F5BF3], Pn(C6F5)3 (Pn = P, As, or Bi), and C6F5X (X = Br or I).
- Koppe, Karsten,Haner, Jamie,Mercier, Hlne P. A.,Frohn, Hermann-J.,Schrobilgen, Gary J.
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p. 11640 - 11661
(2015/01/16)
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- [Li(XeF2)n](AF6) (A = P, As, Ru, Ir), the first xenon(II) compounds of lithium. Synthesis, Raman spectrum, and crystal structure of [Li(XeF2)3](AsF6)
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The reactions between compounds of the type MAF6 (M = alkali metal; A = P, As, V, Ru, Ir, Sb, Nb, Ta) and xenon difluoride were studied in anhydrous hydrogen fluoride solvent. The coordination products [M(XeF 2)n]AsF6 were only observed in the case of LiAF6 (A = P, As, Ru, Ir), and the crystal structure of [Li(XeF 2)3]AsF6 was determined (monoclinic space group P21 with a = 6.901(9) A, b = 13.19(2) A, c = 6.91(1) A, β = 91.84(2), and Z = 2). The coordination sphere of lithium is comprised of six F atoms. The compound series was also characterized by Raman spectroscopy.
- Tavcar, Gasper,Zemva, Boris
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p. 4319 - 4323
(2013/05/22)
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- XeOF3-, an example of an AX3YE2 valence shell electron pair repulsion arrangement; Syntheses and structural characterizations of [M][XeOF3] (M = Cs, N(CH3) 4)
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The XeOF3- anion has been synthesized as its Cs + and N(CH3)4+ salts and structurally characterized in the solid state by low-temperature Raman spectroscopy and quantum-chemical calculations. Vibrational frequency assignments for [Cs][XeOF3] and [N(CH3) 4][XeOF3] were aided by 18O enrichment. The calculated anion geometry is based on a square planar AX3YE 2 valence-shell electron-pair repulsion arrangement with the longest Xe-F bond trans to the oxygen atom. The F-Xe-F angle is bent away from the oxygen atom to accommodate the greater spatial requirement of the oxygen double bond domain. The experimental vibrational frequencies and trends in their isotopic shifts are reproduced by the calculated gas-phase frequencies at several levels of theory. The XeOF3- anion of the Cs + salt is fluorine-bridged in the solid state, whereas the anion of the N(CH3)4+ salt has been shown to best approximate the gas-phase anion. Although [Cs][XeOF3] and [N(CH 3)4][XeOF3] are shock-sensitive explosives, the decomposition pathways for the anions have been inferred from their decomposition products at 20°C. The latter consist of XeF2, [Cs][XeO2F3], and [N(CH3)4][F]. Enthalpies and Gibbs free energies of reaction obtained from Born-Fajans-Haber thermochemical cycles support the proposed decomposition pathways and show that both disproportionation to XeF2, [Cs][XeO2F3], and CsF and reduction to XeF2, CsF, and O2 are favorable for [Cs][XeOF3], while only reduction to XeF2 accompanied by [N(CH3)4][F] and O2 formation are favorable for [N(CH3)4][XeOF3]. In all cases, the decomposition pathways are dominated by the lattice enthalpies of the products.
- Brock, David S.,Mercier, Helene P. A.,Schrobilgen, Gary J.
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p. 10935 - 10943
(2010/09/16)
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- A rare example of a krypton difluoride coordination compound: [BrOF 2][AsF6]-2KrF2
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The synthesis of [BrOF2][AsF6]-2KrF2, its structural characterization, and bonding are described in this study. Although several KrF2 adducts with transition metal centers have been previously reported, none have been crystallographically characterized. The solid-state Raman spectrum of [BrOF2][AsF6]?2KrF 2 has been assigned with the aid of quantum-chemical calculations. The low-temperature (-173 °C) X-ray crystal structure of [BrOF 2][AsF6]?2KrF2 consists of isolated molecular units and represents an example of KrF2 coordinated to a main-group atom. The coordination geometry around the BrOF2+ cation renders the free valence electron lone pair more compact than in free BrOF 2+. The KrF2 ligands are coordinated trans to the fluorine atoms of BrOF2+ with the AsF6- anion coordinated trans to oxygen. The quantum theory of atoms in molecules (QTAIM) and electron localization function (ELF) analyses have been carried out in order to define the nature of the bonding in the complex. A significant amount of charge (0.25 e) is transferred to BrOF2+ from the two KrF2 ligands (0.10e each) and from the AsF6- anion (0.05 e). Significant polarization also occurs within the KrF2 ligands, which enhances the anionic characters of the fluorine bridges. The interaction energy is mostly governed by the electrostatic interaction of the positively charged bromine atom with the surrounding fluorine atoms.
- Brock, David S.,De Casalis Pury, Jonathan J.,Mercier, Helene P. A.,Schrobilgen, Gary J.,Silvi, Bernard
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p. 3533 - 3542
(2010/04/30)
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- Xe3OF3+, a precursor to a noble-gas nitrate; Syntheses and structural characterizations of FXeONO2, XeF2·HNO3, and XeF2·N 2O4
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Xenon fluoride nitrate has been synthesized by reaction of NO2F with [FXeOXeFXeF][AsF6] at -50 °C. It was characterized in SO2ClF and CH3CN solutions by low-temperature 14N, 19F, and 129Xe NMR spectroscopy and in the solid state by low-temperature Raman spectroscopy (-160 °C) and single-crystal X-ray diffraction (-173 °C). The reactions were carried out using natural abundance and 18O-enriched [FXeOXeFXeF][AsF 6] and 15NO2F to aid in the vibrational assignments of FXeONO2 and to establish the likely reaction pathway. Raman spectroscopy showed that FXe16ON(16O18O) was formed, along with XeF2 and [NO2][AsF6], when an excess of N16O2F reacted with [FXe 18OXeFXeF][AsF6]. A reaction mechanism consistent with these findings is discussed. The crystal structure consists of well-separated FXeONO2 molecules which display no significant intermolecular interactions, providing geometric parameters that are in good agreement with the gas-phase values determined from quantum-chemical calculations. Decomposition of solid FXeONO2 is proposed to occur by three reaction pathways to give XeF2, Xe, O2, N2O5, N 2O4, and NO2F. Attempts to synthesize FXeONO2 and Xe(ONO2)2 by reaction of XeF 2 with HNO3 in SO2ClF solution below -30 °C led to XeF2·HNO3. The structure of XeF 2?HNO3 includes a hydrogen bond between HNO 3 and a fluorine atom of XeF2, as well as an interaction between the xenon atom and an oxygen atom of HNO3, leading to a crystal lattice comprised of layered sheets. A molecular addition compound between XeF2 and N2O4 crystallized from liquid N2O4 below 0 °C. The crystal structure of XeF 2?N2O4 displayed weak interactions between the xenon atom of XeF2 and the oxygen atoms of N2O 4. Quantum-chemical calculations have been used to assign the vibrational spectra of FXeONO2, XeF2·HNO 3, and XeF2?N2O4 and to better understand the nature of the interactions of HNO3 and N 2O4 with XeF2. The synthesis of [XeONO 2][AsF6] was attempted by the reaction of FXeONO 2 with excess liquid AsF5 between -78 and -50 °C, but resulted in slow formation of [NO2][AsF6], Xe, and O 2. Thermodynamic calculations show that the pathways to [XeONO 2][AsF6] formation and decomposition are exothermic and spontaneous under standard conditions and at -78 °C.
- Moran, Matthew D.,Brock, David S.,Mercier, Helene P. A.,Schrobilgen, Gary J.
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p. 13823 - 13839
(2010/11/05)
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- Solid-state and solution rearrangements of F3S≡NXeF + leading to the F4S=NXe+ cation; syntheses, HF solvolyses, and structural characterizations of [F4S=NXe][AsF 6] and ...
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The salt, [F 4 S=NXe][AsF 6 ], has been synthesized bythe solid-state rearrangement of [F 3 S≡NXeF][AsF 6] and by HF-catalyzed rearrangement of [F 3 StNXeF][AsF 6 ] in anhydrous HF (aHF) and HF/BrF 5 solvents. The F 4 S=NXe + cation undergoes HF solvolysis to form F 4 S=NH 2 + , XeF 2 , and the recently reported F 5 SN(H)Xe + cation. Both [F 4 S=NXe][AsF 6 ] and [F 4 S=NH 2 ][AsF 6 ] have been characterized by 129 Xe and 19 F NMR spectroscopy in aHF and HF/BrF 5 solvents and by single-crystal X-ray diffraction. The [F 4 S=NXe][AsF 6 ] salt was also characterized by Raman spectroscopy. The Xe-N bond of F 4 S=NXe + is among the shortest Xe-N bonds presently known (2.084(3) ?), and the cation interacts with the AsF 6 - anion by means of a Xe - FsAs bridge in which the Xe - F distance (2.618(2) ?) is significantly less than the sum of the Xe and F van der Waals radii. Both F 4 S=NXe + and F 4 S=NH 2 + exhibit trigonal bipyramidal geometries about sulfur, with nitrogen in the equatorial plane and the nitrogen substituents coplanar with the axial fluorine ligands of sulfur. The F 4 S=NH 2 + cation is isoelectronic with F 4 S=CH 2 and, like F 4 S=CH 2 , has a high barrier to rotation about the S=N double bond and to pseudorotation of the trigonal bipyramidal F 4 S=N- moiety. The solution and solid-state rearrangements of F 3 S≡NXeF + to F 4 S= NXe + are proposed to result from attack at sulfur byfluoride ion arising from HF in solution and from the AsF 6 - anion in the solid state. Quantum-chemical calculations were employed to calculate the gas-phase geometries, charges, bond orders, valencies, and vibrational frequencies of F 4 S=NXe + and F 4 S=NH 2 + . The F 4 S=NXe + cation provides the first example of xenon bonded to an imido-nitrogen, and together with the F 4 S=NH 2 + cation are presently the only cations known to contain the F 4 S=N-group. Both cations are intermediates in the HF solvolysis pathways of F 3 S≡NXeF + which lead to F 5 SN(H)Xe + and F 5 SNH 3 + , and significantly extend the chemistry of the F 4 S=N-group.
- Smith, Gregory L.,Mercier, Helene P. A.,Schrobilgen, Gary J.
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p. 7272 - 7286
(2009/10/17)
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- F5SN(H)Xe+; a rare example of xenon bonded to sp 3-hybridized nitrogen; synthesis and structural characterization of [F5SN(H)Xe][AsF6]
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The salt [F5SN(H)Xe][AsF6] has been synthesized by the reaction of [F5SNH3][AsF6] with XeF 2 in anhydrous HF (aHF) and BrF5 solvents and by solvolysis of [F3S=NXeF][AsF6] in aHF. Both F 5SN(H)Xe+ and F5SNH3+ have been characterized by 129Xe, 19F, and 1H NMR spectroscopy in aHF (-20°C) and BrF5 (supercooled to -70°C). The yellow [F5SN(H)Xe][AsF6] salt was crystallized from aHF at -20°C and characterized by Raman spectroscopy at -45°C and by single-crystal X-ray diffraction at -173°C. The Xe-N bond length (2.069(4) A) of the F5SN(H)Xe+ cation is among the shortest Xe-N bonds presently known. The cation interacts with the AsF6- anion by means of a Xe...F-As bridge in which the Xe...F distance (2.634(3) A) is significantly less than the sum of the Xe and F van der Waals radii (3.63 A) and the AsF6 - anion is significantly distorted from Oh symmetry. The 19F and 129Xe NMR spectra established that the [F 5SN(H)Xe][AsF6] ion pair is dissociated in aHF and BrF5 solvents. The F5SN(H)Xe+ cation decomposes by HF solvolysis to F5SNH3+ and XeF 2, followed by solvolysis of F5SNH3+ to SF6 and NH4+. A minor decomposition channel leads to small quantities of F5SNF2. The colorless salt, [F5SNH3][AsF6], was synthesized by the HF solvolysis of F3S≡NAsF5 and was crystallized from aHF at -35°C. The salt was characterized by Raman spectroscopy at -160°C, and its unit cell parameters were determined by low-temperature X-ray diffraction. Electronic structure calculations using MP2 and DFT methods were used to calculate the gas-phase geometries, charges, bond orders, and valencies as well as the vibrational frequencies of F5SNH 3+ and F5SN(H)Xe+ and to aid in the assignment of their experimental vibrational frequencies. In addition to F 5TeN(H)Xe+, the F5SN(H)Xe+ cation provides the only other example of xenon bonded to an sp3-hybridized nitrogen center that has been synthesized and structurally characterized. These cations represent the strongest Xe-N bonds that are presently known.
- Smith, Gregory L.,Mercier, Helene P. A.,Schrobilgen, Gary J.
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p. 4173 - 4184
(2009/02/01)
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- The oxotrifluoroxenon(VI) cation: X-ray crystal structure of XeOF3+SbF6- and a solution 17O and 129Xe nuclear magnetic resonance study of the 17,18O-enriched XeOF3+ Cation
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The crystal structure of XeOF3+SbF6- has been determined. The compound crystallized in the triclinic system with a = 8.568 (2) ?, b = 9.760 (2) ?, c = 10.104 (2) ?, α = 109.68 (2)°, β = 92.58 (2)°, γ =104.27 (2)°, V = 763.4 ?3, and Dcalc = 3.829 g cm-3 for Z = 4. The structure has been refined in the space group P1 to a final conventional R factor of 0.045 for 1782 independent reflections with I ≥ 2.5σ(I). The structure consists of XeOF3+SbF6- units with two close contacts between the Xe atom of the cation and F atoms of two SbF6- anions. The isolated XeOF3+ cation is shown to be consistent with the VSEPR rules and to possess an AX4E arrangement of the four bond pair domains and the lone pair domain which give rise to a disphenoid-shaped cation having two longer axial Xe-Fax bonds and an Xe-O bond which is coplanar with the shorter equatorial Xe-Feq bond and xenon. Oxygen-17 and -18 enrichment of the XeOF3+ cation in HF and SbF5 solvents has allowed the determination of the 17O chemical shift and 1J(129Xe-17O), as well as the 16,18O induced secondary isotopic shift in the 129Xe NMR spectrum for the first time.
- Mercier, Hélène P. A.,Sanders, Jeremy C. P.,Schrobilgen, Gary J.,Tsai, Scott S.
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p. 386 - 393
(2008/10/08)
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- Silver Trifluoride: Preparation, Crystal Structure, Some Properties, and Comparison with AUF3
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Red, diamagnetic AgF3 is precipitated from anhydrous hydrogen fluoride (AHF) solutions of AgF4- salts by addition of fluoro acids (L) such as BF3, PF5, or AsF5: AgF4-+ L → AgF3 + LF-. With additional AsF5, silver(III) is reduced: AgF3 + AsFf → AgFAsF6 + 1/2F2. Such reduction does not occur with BF3, and the latter acid is therefore preferred for the preparation of stoichiometric AgF3. AgF3 is thermodynamically unstable and, in contact with AHF, at ～20 °C, loses F2 in less than 19 h according to the equation 3AgF3 → Ag3F8 + 1/2F2. The trifluoride is isostructural with AuF3. To provide for meaningful comparisons, the structure of AuF3 was redetermined. AgF3 and AuF3 were successfully refined in space group P61-D62 (No. 178) by using the Rietveld method from time-of-flight neutron powder diffraction data from 100-mg samples contained in 2-mm capillary tubes. The 7762 observations for AgF3 yielded a = 5.0782 (2) A?, c = 15.4524 (8) A?, and V= 345.10 (2) A?3, the reliability parameters for the structure being Rwp = 6.21 and Rp = 3.83%. From the 7646 observations for AuF3, a = 5.1508 (1) A?, c= 16.2637 (7) A?, V= 373.68 (2) A?33, and Rwp = 11.21 and Rp = 7.58%. The lilver or gold atom lies at the center of an elongated octahedron with two Ag-F(1) = 1.990 (3) A?, two Au-F(1) = 1.998 (2) A?, two Ag-F(2) = 1.863 (4) A?, and two Au-F(2) = 1.868 (3) A?, the approximately square, isodimensional AF4 units being joined by symmetrical μ-fluoro bridges (two F(1) in cis relationship in the AF4 unit) to form the 61 (or 65) helical chains where Ag-F(1)-Ag = 123.2 (2)° and Au-F(1)-Au = 119.3 (2)°. The ～5-A?3 smaller formula unit volume of AgF3 compared with AuF3 and the shorter z axis interatomic distance (Ag-F = 2.540 (4), Au-F = 2.756 (8) A?) are in accord with the tighter binding of the Ag(III) d-orbital electrons evident in the strong oxidizing properties of Ag(III). Interaction of AgF+ with AgF4- (1:1) in AHF yields maroon AgIIAgIIIF5. The latter interacts with AgF3 to yield AgIIAgIII2F8, which is identical with the product of the decomposition of AgF3 at 20 °C in AHF and with the material previously described1,2 AgF3. The magnetic susceptibility for AgIIAgIII2F8 obeys the Curie-Weiss law (4-280 K) with θ = -4.2 (5) ° and μeff = 1-924 (3) μB.
- ?emva, Boris,Lutar, Karel,Jesih, Adolf,Casteel Jr., William J.,Wilkinson, Angus P.,Cox, David E.,Von Dreele, Robert B.,Borrmann, Horst,Bartlett, Neil
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p. 4192 - 4198
(2007/10/02)
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- Spontaneous oxidation of xenon to Xe(II) by cationic Ag(II) in anhydrous hydrogen fluoride solutions
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Blue solutions, prepared by dissolving AgF2 in anhydrous hydrogen fluoride (AHF) with BF3 or AsF5, oxidize Xe, at ～20 °C, to produce nearly colorless solids. Overall reactions (all in AHF) are as follows: 2AgF2
- ?emva, Boris,Hagiwara, Rika,Casteel Jr., William J.,Lutar, Karel,Jesih, Adolf,Bartlett, Neil
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p. 4846 - 4849
(2007/10/02)
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- Krypton Bis, Kr(OTeF5)2, the First Example of a Kr-O Bond
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Krypton bis provides the first example of a species containing a krypton-oxygen bond and has been prepared by the reaction of KrF2 with natural abundance and 17O-enriched B(OTeF5)3 at -90 to -112 deg C in SO2ClF solvent; characterization of the thermally unstable Kr(OTeF5)2 and its decomposition products has been achieved using 19F and 17O n.m.r. spectroscopy.
- Sanders, Jeremy C. P.,Schrobilgen, Gary J.
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p. 1576 - 1578
(2007/10/02)
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- The Fluoro(perfluoroalkylnitrile)noble-gas(II) Cations, RFCN-NgF+ (Ng = Kr or Xe; RF = CF3, C2F5, n-C3F7), and the Fluoro(trifluoro-s-triazine)xenon(II) Cation, s-C3F3N2N-XeF+; Novel Noble Gas-Nitrogen Bonds
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Three novel examples of Kr-N bonds derived from perfluoroalkylnitriles, the RFCN-KrF+ cations, and their xenon analogues RFC-XeF+ (RF = CF3, C2F5, n-C3F7), have been prepared and characterized i
- Schrobilgen, Gary J.
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p. 1506 - 1508
(2007/10/02)
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- Crystal structure, Raman, and multinuclear magnetic resonance study of FXeN(SO2F)2, an example of xenon-nitrogen bonding
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The crystal structure of fluoro[imidobis(sulfuryl fluoride)]xenon(II) has been determined at -55 °C from three-dimensional X-ray data. The compound crystallizes in the monoclinic system, space group P21/a, with four molecules in a unit cell of dimensions a = 11.827 (4) A?, b = 6.828 (2) A?, c = 9.467 (3) A?, and β= 112.65 (2)°. The structure was solved by the heavy-atom method and refined by least-squares and Fourier methods to a final R factor of 0.023 for 1721 observed (F > 6σ(F)) reflections. The structure analysis has established the existence of discrete FXeN(SO2F)2 molecules and shows that FXeN(SO2F)2 is Xe-N bonded, representing the first definitive proof for the existence of the Xe-N bond. The xenon atom is approximately linearly coordinated by the nitrogen atom of the imidobis(sulfuryl fluoride) group and a fluorine atom. The angle F-Xe-N is 178.1 (1)°, and the interatomic distances are Xe-N = 2.200 (3) A? and Xe-F = 1.967 (3) A?. Raman spectral data and assignments are also presented for FXeN(SO2F)2, HN(SO2F)2, and Cs+N(SO2F)2-. Solution 15N, 129Xe, and 19F NMR studies of 15N-enriched FXeN(SO2F)2 demonstrate that FXeN(SO2F)2 is also Xe-N bonded in solution. The first example of a directly bonded 129Xe-15N coupling (305 Hz) is also reported.
- Sawyer, Jeffery F.,Schrobilgen, Gary J.,Sutherland, Steven J.
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p. 4064 - 4072
(2008/10/08)
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- The xenon-fluorine system
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Equilibrium constants have been obtained in the Xe-F2 system in the temperature range 250-500°. The data show that only three binary fluorides, XeF2, XeF4, and XeF6, are present. There is no evidence for the existence of XeF8 at 250° and up to 500 atm of F2. A preparation of pure XeF6 is described. A molecular weight determination, some infrared measurements, and vapor pressure data obtained with this sample are reported. Values for the thermodynamic properties of formation of XeF2, XeF4, and XeF6 are derived from the equilibrium constant data. The average value of the two missing vibrational modes of XeF4 is evaluated to be 246 ± 10 cm-1 from an analysis of the equilibrium constant and molecular data. Thermodynamic properties of XeF2 and XeF4 are calculated from molecular data. The value of S° for XeF4 at 25° is 75.6 cal mole-1 deg-1, in agreement with a value of 75.3 cal mole-1 deg-1 calculated from calorimetric data and the heat of sublimation. A number of molecular models for XeF6 are examined in terms of their consistency with the equilibrium constant data. A definite choice among the various models is not possible, but the analysis favors a low symmetry for XeF6. Values of S° for XeF6 at 25° are derived for each model and may be useful to help determine the symmetry of XeF6 when calorimetric data become available. The average bond energy of XeF2 is 31.0 kcal and that of XeF4 is 30.9 kcal. For XeF6 the average bond energy is 29.7 kcal, so that the average energy for forming the last two bonds in XeF6 is 27.3 kcal.
- Weinstock, Bernard,Weaver, E. Eugene,Knop, Charles P.
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p. 2189 - 2203
(2008/10/08)
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