- Enthalpies of Formation of Gas-Phase N3, N3-, N5+, and N5- from Ab Initio Molecular Orbital Theory, Stability Predictions for N5+ N3- and N5+N5-, and Experimental Evidence for the Instability of N5+N3-
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Ab initio molecular orbital theory has been used to calculate accurate enthalpies of formation and adiabatic electron affinities or ionization potentials for N3, N3-, N5 +, and N5-/su
- Dixon, David A.,Feller, David,Christe, Karl O.,Wilson, William W.,Vij, Ashwani,Vij, Vandana,Jenkins, H. Donald Brooke,Olson, Ryan M.,Gordon, Mark S.
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- Indium(I) hexafluoropnictates (InPnF6; Pn = P, As, Sb)
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The colourless compounds InPnF6 (Pn = P, As, Sb), with In I in a solely fluorine environment, were prepared by reacting In metal with PnF5 (Pn = P) and displacement of the weaker Lewis acid BF3 from InBF4 by a stronger one, PnF5 (Pn = As, Sb), in anhydrous hydrogen fluoride (aHF). The X-ray powder diffraction analyses show that InPF6 crystallises in cubic unit cell with a = 8.07(2) A, while InAsF6 crystallises in a rhombohedral unit cell with a = 7.58(2) and c = 7.90(1) A. The Raman spectra of InPnF 6 (Pn = P, As, Sb) confirm the formation of PnF6 - salts. An attempt to prepare InF and In2F4 (InIInIIIF4) by reaction of CsF with InSbF 6 in aHF or by metathetical reaction of InSbF6 with CsInF4 in aHF, respectively, failed. Instead of InF and In 2F4, respectively, a mixture of In and InF3 was obtained. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
- Mazej, Zoran
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- Crystal Growth and Characterization of the Mixed-Cation Rb+/[XeF5]+ and Cs+/[XeF5]+ Salts
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Reactions between ASbF6 (A = Rb, Cs) and [XeF5][SbF6] in anhydrous HF in 1:1 molar ratios yielded isotypic A[XeF5][SbF6]2 compounds upon crystallization. The A[XeF5][SbF6]2 (A = Rb, Cs) salts crystallize in two crystal modifications at low (α phase, 150 K) and ambient (β phase, 296 K) temperatures. Similar reactions between CsBiF6 and [XeF5][SbF6] (1:1) yielded mixed-cation/mixed-anion compounds Cs[XeF5][BixSb1–xF6]2 (x = 0.37–0.39). One of the two crystallographic positions of the pnictogen atoms is randomly occupied with both Bi (ca. 40 %) and Sb (ca. 60 %) atoms. The simultaneous presence of both [SbF6]– and [BiF6]– has been confirmed by Raman spectroscopy. The low- and high-temperature phases of Bi/Sb mixed-anion compounds are isotypic with the corresponding A[XeF5][SbF6]2 (A = Rb, Cs) phases. No reactions were observed in the AAsF6 (A = Rb, Cs)/[XeF5][AsF6], ASbF6 (A = K, [H3O]+)/[XeF5][SbF6], and KBF4/[XeF5][SbF6] systems. In the CsBF4/[XeF5][SbF6] system, a metathetical reaction occurred, leading to [XeF5][BF4] (orthorhombic at 150 K, Pbca space group) and CsSbF6. The latter reacted further with [XeF5][SbF6], yielding Cs[XeF5][SbF6]2. A double-displacement reaction also proceeded between Cs2MnF6 and [XeF5][SbF6] to give [XeF5]2[MnF6] and CsSbF6. The reaction between CsPF6 and [XeF5][SbF6] proceeded with the displacement of the weaker Lewis acid, PF5, with the stronger one, SbF5, resulting in [Xe2F11][SbF6] and CsSbF6, which reacted with [XeF5][SbF6] to yield Cs[XeF5][SbF6]2.
- Mazej, Zoran,Goreshnik, Evgeny
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p. 2800 - 2807
(2017/06/13)
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- The reduction of AuF3 in super acidic solution
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AuF3 is reduced in superacidic HF/SbF5 solutions giving three products. 1 Orange [Au3F8·2SbF5]. It has a layered structure built up by square planar AuIIF4 and AunIIIF4 units: Crystal structure: space group P21/c, a = 9.049(2), b = 8.424(1), c = 9.645(1) A, β = 115.08(1)°. 2. Black [Au3F7·3SbF5] has a ribbon structure, similarly built up by square planar AuIIF4 and AuIIIF4 units: Crystal structure: fipace group Pc, a = 9.991(1), b = 10.728(1), c = 15.222(1)A, β = 95.304(2)°. 3. Yellow green [(Au(HF)2] [SbF6)2·2HF with square planar Au↑F4 units that are formed by two fluorine atoms of the anions and two HF molecules as complex ligands. Crystal structure: Space group P1, a = 5.482(1), b = 5.848(1), c = 9.309(2) A, α = 89.522(4), β = 85.635(4), γ = 87.509(4)°.
- Hwang, In-Chul,Seppelt, Konrad
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p. 765 - 769
(2008/10/08)
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- Bis(carbonyl)platinum(II) derivatives: Molecular structure of cis-Pt(CO)2(SO3F)2, complete vibrational analysis of cis-Pt(CO)2Cl2, and attempted synthesis of cis-PT(CO)2F2
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As part of a comprehensive study of square planar palladium(II) and platinum(II) carbonyl derivatives, the molecular structure of cis-Pt(CO)2(SO3F)2, the complete vibrational spectra of cis-Pt(CO)2Cl2, and the attempted synthesis of cis-Pt(CO)2F2 are reported, cis-Pt(CO)2(SO3F)2 is isostructural with cis-Pd(CO)2(SO3F)2 and crystallizes in the monoclinic space, group P21/n (no. 14). Crystal data: a = 7.419(1) A; b = 14.751(2) A; c =8.634(1) A; β = 89.95(1)°; V= 944.9(2) A3; Z = 4; T = 300 K; R [F(o) > 4σ(F(o)) = 0.0447 and wR2 = 0.1097. The internal bond parameters of the cis-Pt(CO)2(SO3F)2 are compared to those of cis-Pd(CO)2(SO3F)2, cis-Pt(CO)2Cl2, and [M(CO)4]2+, M = Pd, Pt. Solid cis-Pt(CO)2Cl2 is studied by IR and Raman spectroscopy, and the data are compared to those of the matrix-isolated complex by IR spectroscopy. Vibrational assignments are supported by DFT calculations, which provide, in addition to vibrational wavenumbers, estimates of IR and Raman band intensities. The positions of 12 of the expected 15 fundamentals of cis-Pt(CO)2Cl2 are obtained experimentally. Attempts to synthesize cis-Pt(CO)2F2, using, in addition to cis-Pt(Co)2X2, X = Cl or SO3F, [Pt(CO)4][Sb2F11]2 or PtF6 as starting material and toluene or anhydrous hydrogen fluoride as the reaction medium, are unsuccessful. There are however two interesting results: The reductive carbonylation of PtF6 in HF produces with [Pt(CO)4][PtF6] the first carbonyl fluoride of platinum, and the reaction of [Pt(CO)4][Sb2F11]2 and CsF in HF results in the formation of the previously reported anionic cluster complex Cs2[Pt3(CO)6](n?10). The inclusion of [M(CO)4]2+, M = Pd, Pt, provides new insights into the nature of the Pd(II)-CO and Pt(II)-CO bonds.
- Von Ahsen, Britta,Wartchow, Rudolf,Willner, Helge,Jonas, Volker,Aubke, Friedhelm
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p. 4424 - 4432
(2008/10/08)
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- Seven-coordinated pnicogens. Synthesis and characterization of the SbF72- and BiF72- dianions and a theoretical study of the AsF72- dianion
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The novel seven-coordinated BiF72- and SbF72- dianions have been prepared and characterized. The Cs2BiF7, Rb2BiF7, K2BiF7, and Na2BiF7 salts were obtained in high yield by heating BiF5 with an excess of the corresponding alkali metal fluorides to about 250 °C. Attempts failed to prepare the corresponding BiF83- salts or Li2BiF7 under similar conditions. The [N(CH3)4]2BiF7 salt was obtained by the combination of excess N(CH3)4F with BiF5 in CH3CN solution at -31 °C. The (NO2)2BiF7 salt was prepared from BiF5 and a large excess of liquid FNO at -78 °C and decomposes at room temperature to NOBiF6 and FNO. The corresponding Cs2SbF7, K2SbF7, and [N(CH3)4]2SbF7 salts were also synthesized in a similar fashion, but Na2SbF7 was not formed. The pronounced fluoride ion affinity of SbF6- was further demonstrated by the formation of some Cs2SbF7 when dry CsF and CsSbF6 were ball-milled at room temperature. The BiF72- and SbF72- anions, which are the first examples of binary pnicogen compounds with coordination numbers in excess of six, were characterized by vibrational spectroscopy and ab initio electronic structure calculations. They possess pentagonal bipyramidal, highly fluxional structures of D(5h) symmetry, similar to those of IF7 and TeF7-, which are isoelectronic with SbF72-. Although our theoretical calculations indicate that AsF72- is also vibrationally stable, experiments to prepare this dianion were unsuccessful.
- Drake, Greg W.,Dixon, David A.,Sheehy, Jeffrey A.,Boatz, Jerry A.,Christe, Karl O.
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p. 8392 - 8400
(2007/10/03)
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- RbAsF6, CsAsF6 and RbSbF6: Crystal structures, thermal phase transitions, and vibrational spectra
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The title compounds are isostructural to CsSbF6 and crystallize with the KOsF6 structure type (space group R3, Z = 3) with the lattice constants a = 749.7(1) pm, c = 758.9(1) pm (RbAsF6), a = 772.3(1) pm, c = 805.0(1) pm (CsAsF6) and a = 767.0(1) pm, c = 786.1(2) pm (RbSbF6). The structures exibit nearly ideal [MF6]- octahedra, the alkaline cations are coordinated by 12 fluorine ions in a distorted cuboctahedral geometry. Cations and complex anions form a slightly distorted CsCl arrangement. On heating, the arsenates transform to a NaCl arrangement with disordered [AsF6] ions, whereas the antimonates of Rb and Cs form the corresponding disordered CsCl type at higher temperatures. The phase transitions and the i. r. and Raman spectra as well as the structural relations to the remaining hexafluoropnictates AI[MVF6] are discussed.
- Loss, Sandra,Roehr, Caroline
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- Reaction of azides with dioxygenyl salts: Is dioxygenyl azide existent?
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The reactivity of sodium azide, activated sodium azide and hydrazinium azide towards various dioxygenyl tetrafluoroborate and dioxygenyl hexafluoroantimonate salts was studied both at low temperature in SO2 solution and in the solid state. Under no circumstances the formation of dioxygenyl azide, O2N3, could be observed. This is in agreement with high level quantumchemical ab initio computations at correlated level (MP2, PMP2, CISD), predicting the decomposition of hypothetical O2+(g) / N3-(g) to be thermodynamically highly favourable (MP2: -326; PMP2: -328; CISD: -369 kcal mol-1). Moreover, no true minimum for covalently bound dioxygenyl azide was found at any level of theory applied. The combustion of O2BF4 with either N2H5N3 (spontaneous reaction on contact in a coaxial solid-propellant system) or NaN3 (safe to handle, highly exothermic reaction after ignition) is discussed in terms of high energetic materials. Gauthier-Villars.
- Holfter,Klapoetke,Schulz
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p. 855 - 864
(2008/10/08)
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- Formation and NMR Spectroscopic Characterization of the Fluorophosphonium Cations, PH4-nFn+ (n = 1-4)
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The preparations of the salts PH3F+SbF6- and PHF3+Sb2F11- are reported.All fluorophosphonium cations PH4-nFn+ are characterized by multinuclear (1H, 19F, 31P) NMR spectroscopy.For n > 1 these salts are easily accessible by fluoride abstraction from fluorohydridophosphates(V).PH3F+SbF6-, however, is obtained in the reaction of PH3F2 with SbF5. - keywords: Fluorophosphonium Salts, Formation, NMR Spectra
- Minkwitz, Rolf,Liedtke, Andreas
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p. 679 - 682
(2007/10/02)
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- Synthesis and characterization of NF4CrF6 and reaction chemistry of CrF5
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NF4CrF6, a new stable NF4+ salt containing an energetic counterion, was prepared by treatment of CrF5 with an excess of NF4HF2 in HF solution. The composition and ionic nature of NF4CrF6 was established by elemental analysis, vibrational and 19F NMR spectroscopy, and its X-ray powder pattern. Reactions of CrF5 with H2O in HF, ClF3, FNO, Cl2, CFCl3, and KrF2 were studied to determine its acidity and oxidizing power. With FNO, a stable 1:1 adduct is formed, which on the basis of its vibrational spectra has the ionic structure NO+CrF6-. The reaction of NOCrF6 with NO produced (NO+)2CrF62-, which by controlled pyrolysis was converted to NO+CrF5-. With stoichiometric amounts of H2O in HF, CrF5 did not form a stable OH3+CrF6- salt but the reaction resulted in hydrolysis to CrF3O. The influence of the strong Lewis acids AsF5 and SbF5 on the oxidizing power of CrF5 was also investigated. On the basis of the fact that CrF5-SbF5 mixtures can oxidize O2 (IP = 12.06 eV) but not NF3 (IP = 13.00 eV), the following qualitative oxidizer strength scale is proposed: KrF+ > PtF6 > SbF5 + F2 + activation energy > CrF5-SbF5. The results of a normal-coordinate analysis of CrF6- and CrF62- show the expected decrease in force constants with increasing negative charge.
- Bougon, Roland,Wilson, William W.,Christe, Karl O.
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p. 2286 - 2292
(2008/10/08)
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- Coordinatively saturated fluoro cations. Oxidative fluorination reactions with KrF+ salts and PtF6
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The usefulness of KrF+ salts and PtF6 as oxidative fluorinators for the syntheses of the coordinatively saturated complex fluoro cations NF4+, ClF6+, and BrF6+ was studied. The syntheses of NF4SbF6, NF4AsF6, NF4BF4, and NF4TiF5·nTiF4 from KrF2-Lewis acid adducts and NF3 were investigated under different reaction conditions. The fluorination of NF3 by KrF+SbF6- in HF solution was found to proceed quantitatively at temperatures as low as -31°C, indicating an ionic two-electron oxidation mechanism. An improved synthesis of KrF+MF6- (M = As, Sb), Raman data and solubilities in HF, and the existence of a Kr2F3+·nKrF2BF 4- adduct in HF at -40°C are reported. Attempts to fluorinate OF2, CF3NF2, and ClF4O- with KrF+ salts were unsuccessful. Whereas KrF+ is capable of oxidizing NF3, ClF5, and BrF5 to the corresponding complex fluoro cations, PtF6 was shown to be capable of oxidizing only NF3 and ClF5. Since the yield and purity of the NF4+ fluoroplatinate salts obtained in this manner were low, NF4PtF6 was also prepared from NF3, F2, and PtF6 at elevated temperature and pressure. General aspects of the formation mechanisms of coordinatively saturated complex fluoro cations are discussed briefly.
- Christe, Karl O.,Wilson, William W.,Wilson, Richard D.
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p. 2058 - 2063
(2008/10/08)
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- Perfluoroammonium and alkali-metal salts of the heptafluoroxenon(VI) and octafluoroxenon(VI) anions
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The NF4XeF7 salt was prepared from XeF6 and NF4HF2 and was converted to (NF4)2XeF8 by selective laser photolysis. These new salts and the known CsXeF7 and Cs2XeF8 were characterized, and their vibrational spectra are reported. Evidence is presented for the existence of a stable NaXeF7 salt. The presence of different phases in solid XeF6 was confirmed by Raman spectroscopy.
- Christe, Karl O.,Wilson, William W.
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p. 4113 - 4117
(2008/10/08)
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- Syntheses and properties of FOIF4O, ClOIF4O, HOIF4O, and tetrafluoroperiodates
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Mixtures of cis- and trans-CsIF4O2 were prepared by the interaction of CsIO4 with either anhydrous HF, BrF5, ClF3, ClF5, or F2. The vibrational spectra of these mixtures were recorded, and partial assignments are given for cis- and trans-IF4O2-. The assignments for trans-IF4O2- were supported by a normal-coordinate analysis. The CsIF4O2 salt dissolves in CH3CN with the formation of IF4O2- anions but undergoes solvolysis in anhydrous HF with formation of HOIF4O. An improved synthesis of HOIF4O from CsIF4O2 and BiF5 in anhydrous HF is reported, and its Raman and 19F NMR spectra were recorded. The interaction of CsIF4O2 with NF4SbF6 in anhydrous HF results in solutions containing NF4+, HF2-, and HOIF4O. When standing or when pumped to dryness, these mixtures decompose to yield NF3 and the new compound FOIF4O in high yield. The latter compound, the first known example of an iodine hypofluorite, was thoroughly characterized and shown by vibrational and NMR spectroscopy to be a mixture of the cis and trans isomers. For comparison, the vibrational spectra of IF5O have also been recorded. The reaction of CsIF4O2 with ClOSO2F was shown to yield the novel compound ClOIF4O. The fluorination reactions of CsIO4, CsIF4O2, IF5O, and HOIF4O with elementary fluorine were also studied.
- Christe, Karl O.,Wilson, Richard D.,Schack, Carl J.
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p. 2104 - 2114
(2008/10/08)
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- Synthesis and properties of NF4+ClO4- and NF4+HF2-·nHF and some reaction chemistry of NF4+ salts
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The possibility of synthesizing NF4+XO4- (X = Cl, Br, I) salts by metathesis between NF4SbF6 and CsXO4 in anhydrous HF solution at -78°C was studied. Of these NF4XO4 salts, NF4ClO4 was isolated and characterized by vibrational and 19F NMR spectroscopy. It is an unstable white solid decomposing at 25°C to give NF3 and FOClO3 in high yield. The NF4BrO4 salt is of marginal stability in HF solution and decomposes to NF3, O2, and FBrO2. Attempts to isolate NF4BrO4 as a solid resulted in explosions. The NF4IO4 salt could not be prepared due to the facile fluorination of IO4- to IF4O2- by either HF or BrF5. Attempts to prepare NF4+XF4O- (X = Cl, Br) salts by metathesis between NF4SbF6 and CsXF4O in BrF5 solution at 25°C were unsuccessful; with BrF4O-, fluoride abstraction occurred, resulting in the formation of NF3, F2, and BrF3O, whereas CsClF4O underwent a displacement reaction with BrF5 to give CsBrF6 and ClF3O. The metathetical synthesis of NF4NO3 could not be studied in HF due to the reaction of NO3- with HF to give NO2+, H2O, and HF2-. The metathesis between NF4SbF6 and CsF in HF at -78°C did not produce NF4+F- but produced an unstable white solid of the composition NF4+HF2-·nHF. The composition, thermal stability, spectroscopic properties, and decomposition products of this solid were studied. The NF4+HF2- salt is stable in HF solution at 25°C, and the synthetic usefulness of these solutions for the synthesis of other NF4+ salts is briefly discussed. Attempts to prepare NCl4+ and NCl2O+ salts by F-Cl exchange between BCl3 and NF4+ and NF2O+ were unsuccessful.
- Christe, Karl O.,Wilson, William W.,Wilson, Richard D.
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p. 1494 - 1498
(2008/10/08)
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