- Solid-State Structure of Protonated Ketones and Aldehydes
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Protonated carbonyl compounds have been invoked as intermediates in many acid-catalyzed organic reactions. To gain key structural and electronic data about such intermediates, oxonium salts derived from five representative examples of ketones and aldehydes are synthesized in the solid state, and characterized by X-ray crystallography and Raman spectroscopy for the first time. DFT calculations were carried out on the cations in the gas phase. Whereas an equimolar reaction of the carbonyl compounds, acetone, cyclopentanone, adamantanone, and acetaldehyde, with SbF5 in anhydrous HF yielded mononuclear oxonium cations, the same stoichiometry in a reaction with benzaldehyde resulted in formation of a hemiprotonated, hydrogen-bridged dimeric cation. Hemiprotonated acetaldehyde was obtained when a 2:1 ratio of aldehyde and SbF5 was used. Experimental and NBO analyses quantify the significant increase in electrophilicity of the oxonium cations compared to that of the parent ketones/aldehydes.
- Stuart, Daniel,Wetmore, Stacey D.,Gerken, Michael
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- Hexakis(carbonyl)iron(II) undecafluorodiantimonate(V), [Fe(CO)6][Sb2F11]2, and -hexafluoroantimonate(V), [Fe(CO)6][SbF6]2, their syntheses, and spectroscopic and structural characterization by single crystal X-ray diffraction and normal coordinate analysis
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Hexakis(carbonyl)iron(II) undecafluorodiantimonate(V), [Fe(CO)6][Sb2F11]2, is conveniently prepared by the oxidative carbonylation of Fe(CO)5 with XeF2 as external oxidizer in the conjugate Bronsted-Lewis superacid HF-SbF5. The colorless compound crystallizes from the reaction medium in high purity. The molecular structure is obtained by single-crystal X-ray diffraction. The cation is a regular octahedron, while the vertex-shared di-octahedral [Sb2F11]- anion is distorted from D4(h) symmetry by bending and rotational processes, due to significant interionic interactions, primarily of the F · · · C type. Washing of [Fe(CO)6][Sb2F11]2 with anhydrous HF results in an unusual elution of SbF5 and the quantitative conversion to hexakis(carbonyl)iron(II) hexafluoroantimonate(V) [Fe(CO)6][SbF6]2. The molecular structure of the salt shows octahedral ions with slight tetragonal distortions for the cation (elongation) and the anion (compression). Both salts are thermally stable up to 150 °C. The averaged bond distances and the vibrational wavenumbers of [Fe(CO)6]2+ are nearly identical in both compounds. The [Fe(CO)6]2+ cation, the first and so far only isolated and structurally characterized dipositive, superelectrophilic carbonyl cation formed by a 3d-metal, is further characterized by a normal coordinate analysis (NCA). The obtained force constants are compared to those of the isoelectronic molecule Cr(CO)6. Changes in π-back-bonding affect the F(CO/CO) and F(CO/MC) interaction force constants more strongly than the stretching force constants F(CO) and F(MC). All 13 fundamentals of [Fe(CO)6]2+ are detected and assigned with the help of the data obtained from the normal coordinate analysis and density functional calculations published previously. The electronic ground state 1A1(g) of the [Fe(CO)6]2+ cation is established by magnetic susceptibility measurements of polycrystalline [Fe(CO)6][SbF6]2 and [Fe(CO)6][Sb2F11]2 between 2 and 300 K. The magnetic impurity formed during synthesis is identified as Fe[SbF6]2 which has iron(II) in high spin (5T2(g)) ground state. Consistent with a diamagnetic ground state are the single line in the 57Fe Mossbauer spectrum (i.s. = -0.003(8) mm s-1 relative to α-Fe), obtained on polycrystalline samples and the single sharp line in the 13C NMR spectrum in DF solution at 178 ppm with J (57Fe- 13C) of 19.2 Hz.
- Bernhardt, Eduard,Bley, Bianca,Wartchow, Rudolf,Willner, Helge,Bill, Eckhard,Kuhn, Peter,Sham, Iona H. T.,Bodenbinder, Matthias,Br?chler, Raimund,Aubke, Friedhelm
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- Preparation and characterization of (CNSSS)2(A)2 (A = AsF6-, SbF6-, Sb2F 11-) containing the O2-like 5,5′-Bis(1,2,3,4-trithiazolium) dication: The second example of a simple nonsterically hindered main-group diradical that retains its paramagnetism in the solid state
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The reaction of NC-CN with a 1:1 mixture of S4(MF 6)2 and S8(MF6)2 (M = As, Sb) (stoichiometrically equivalent to four S3MF 6 units) results in the quantitative formation of S 3NCCNS3(MF6)2 [7(MF 6)2], which is the thermodynamic sink in this reaction. The Sb2F11- salt 7(Sb2F 11)2 is prepared by the addition of an excess of SbF 5 to 7(AsF6)2. Crystal structure determinations for all three salts show that 72+ can be viewed as two R-CNS 3+ radical cations joined together by a C-C single bond. The two rings are coplanar and in a trans orientation due to electrostatic Nδ-...Sδ+ interactions. The classically bonded alternative (quinoidal structure), in which the octet rule is obeyed, is not observed and is much higher in energy based on calculated estimates and a simple comparison of π bond energies. Calculated molecular orbitals (MOs) support this, showing that the MO corresponding to the quinoidal structure lies higher in energy than the nearly degenerate singly occupied MOs of 7 2+. The vibrational spectra of 72+ in all salts were assigned based on a normal-coordinate analysis and theoretical vibrational frequencies calculated at the PBE0/6-31G* level. In the solid state, 72+ is a planar disjoint diradical with essentially degenerate open-shell singlet and triplet states. The disjoint nature of the diradical cation 72+ is established by magnetic susceptibility studies of the Sb2F11- salt doped in an isomorphous diamagnetic host material (CNSNS)2(Sb2F11) 2 [10(Sb2F11)2]. Intramolecular spin coupling is extremely weak corresponding to a singlet-triplet gap (δEST = 2J) of -1. CASPT2[12,12]/6-311G* calculations support a triplet ground state with a small singlet-triplet gap. The single-crystal electron paramagnetic resonance (EPR) of 7(Sb2F11)2 doped in 10(Sb 2F11)2 is in agreement with the triplet state arising from the weak coupling between the unpaired electrons residing in p π orbitals in each of the rings. Variable-temperature susceptibility data for bulk samples of 7(A)2 (A = SbF 6-, AsF6-, Sb2F 11-) are analyzed by employing both 1D chain and 2D sheet magnetic models. These studies reveal significant intermolecular exchange approximating that of a 1D chain for the SbF6- salt with |J| = 32 cm-1. The exchange coupling is on the same order of magnitude as that for the AsF6- salt, although in this case it is likely that there are complex exchange pathways where no particular one is dominant. Intermolecular exchange in the Sb2F 11- salt is an order of magnitude weaker. In solution, the EPR spectrum of 72+ shows a broad triplet resonance as well as a sharp resonance that is tentatively attributed to a rotomer of the 7 2+/anion pair, which is likely the origin of the green species given on dissolution of the red 72+ salts in SO2/AsF 3/MF5. We account for the many similarities between O 2 and 72+, which are the only simple nonsterically hindered nonmetal diradicals to retain their paramagnetism in the solid state. 72+ is also the first isolable, essentially sulfur-based diradical as evidenced by calculated spin densities.
- Cameron, T. Stanley,Decken, Andreas,Grein, Friedrich,Knapp, Carsten,Passmore, Jack,Rautiainen, J. Mikko,Shuvaev, Konstantin V.,Thompson, Robert C.,Wood, Dale J.
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- Mixed Noble-Gas Compounds of Krypton(II) and Xenon(VI); [F5Xe(FKrF)AsF6] and [F5Xe(FKrF)2AsF6]
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The coordination chemistry of KrF2 has been limited in contrast with that of XeF2, which exhibits a far richer coordination chemistry with main-group and transition-metal cations. In the present work, reactions of [XeF5][AsF6] with KrF2 in anhydrous HF solvent afforded [F5Xe(FKrF)AsF6] and [F5Xe(FKrF)2AsF6], the first mixed krypton/xenon compounds. X-ray crystal structures and Raman spectra show the KrF2 ligands and [AsF6]? anions are F-coordinated to the xenon atoms of the [XeF5]+ cations. Quantum-chemical calculations are consistent with essentially noncovalent ligand?xenon bonds that may be described in terms of σ-hole bonding. These complexes significantly extend the XeF2–KrF2 analogy and the limited chemistry of krypton by introducing a new class of coordination compound in which KrF2 functions as a ligand that coordinates to xenon(VI). The HF solvates, [F5Xe(FH)AsF6] and [F5Xe(FH)SbF6], are also characterized in this study and they provide rare examples of HF coordinated to xenon(VI).
- Lozin?ek, Matic,Mercier, Hélène P. A.,Schrobilgen, Gary J.
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- Fluoride Ion Donor Properties of UF2O2; Preparation and Characterization of the Adducts UF2O2*nSbF5 (n=2 or 3) and Crystal Structure of UF2O2*3SbF5
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The adducts UF2O2*nSbF5 (n=2 or 3) have been obtained as pale green and pale yellow-green solids respectively from the reaction of UF2O2 with SbF5 in HF solvent.The solid adducts have been characterized by observation of reaction stoicheiometries, chemical analyses, and vibrational spectra.An X-ray diffraction study has shown that crystals of UF2O2*3SbF5 are monoclinic, space group P21/n, with unit-cell dimensions a=11.040(7), b=12.438(12), c=12.147(8) Angstroem, β=111.16(20) degree, and Z=4.The structure has been refined by three-dimensional least-squares methods to R=0.0773 for 1613 reflections.The structure is best regarded as a fluorine-bridged network of UF2O2 and SbF5 molecules in which the antimony is surrounded by a distorted octahedron of fluorine atoms and the uranium by a pentagonal-bipyramidal array of five fluorines and two oxygens.Two of the uranium-fluorine distances are long and this means that the structure can also be described in terms of zigzag chains of UO2 groups fluorine-bridged to SbF6 units with Sb2F11 side-chains attached to the uraniums.
- Fawcett, John,Holloway, John H.,Laycock, David,Russell, David R.
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- Trifluoroacetate as a Bridging Ligand for Antimony(V): Crystal and Molecular Structures of μ-Fluoro-μ-trifluoroacetato-bis (1) and of μ-Oxo-di-μ-trifluoroacetato-bis (2)
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Crystals of title compound (1), Sb2(O2CCF3)F9, are monoclinic.Space group P21/c with a=9.386(6), b=15.119(8), c=16.250(7) Angstroem, β=110.52(11) deg, and Z=8.The asymmetric unit contains two equivalent but crystallographically independent binuclear complexes in which the Sb atoms are bridged by a F atom (Fb) and by a trifluoroacetato-group.The distorted octahedral co-ordination at each Sb centre is completed by four terminal F atoms (Ft).The mean bond distances are: Sb-Fb 2.025(21), Sb-O 2.026(23), and Sb-Ft 1.836(24) Angstroem.The heavy atoms have been located directly and full-matrix least-squares refinement with anisotropic thermal parameters for the Sb atoms has given R=0.090 with 1 791 independent observed reflections.Title compound (2), Sb2O(O2CCF3)2F6, crystallizes in the monoclinic space group Cc with a=12.322(6), b=13.867(8), c=9.443(5) Angstroem, β=122.75(5) deg, and Z=4.The two Sb atoms are bridged by an oxygen atom (Ob) and by two trifluoroacetato-groups with the octahedral co-ordination at Sb completed by terminal fluorines (Ft).The binuclear complex has approximate C2v symmetry and exhibits the following mean bond distances: Sb-Ob 1.893(21), Sb-O 2.064(16), and Sb-Ft 1.840(17) Angstroem.The analysis is based on 1 760 independent observed reflections and refined by weighted full-matrix least-squares analysis to R=0.043.
- Bullivant, David P.,Dove, Michael F. A.,Haley, Martin J.
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- Crystal Structures of Hydrazinium(II) Salts of [SbF6]- and [Sb2F11]-
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N2H6(Sb2F11)2 was synthesized by the reaction of N2H6F2 with excess of SbF5 in anhydrous hydrogen fluoride (aHF). It crystallizes in the triclinic space group P 1ˉ (No. 2) with a = 6.6467(3) ?, b = 8.3039(4) ?, c = 8.3600(5) ?, α = 76.394(5) o, β = 70.161(5) o, γ = 70.797(5) o, V = 405.90(4) ?3 at 150 K, Z = 2. When it is redissolved in aHF, it solvolysis with the release of SbF5 yielding N2H6(SbF6)2 which crystallizes in the monoclinic C2/c space group (No. 15) with a = 7.3805(3) ?, b = 12.3248(5) ?, c = 10.4992(4) ?, β = 92.218(4) o, V = 954.33(7) ?3 at 150 K, and Z = 8. No other phases were observed in crystallization products when different molar ratios of N2H6F2/SbF5 (1:1,2:3,1:3) in aHF were used as starting materials.
- Mazej, Zoran,Goreshnik, Evgeny A.
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- METHOD FOR MANUFACTURE OF 1,1,1-TRIFLUORO-2-CHLOROETHANE (HCFC 133A) AND/OR TRFLUOROETHYLAMINE (TFEA)
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A method for manufacture of 1, 1, 1-trifluoro-2-chloroethane (HCFC-133a) and/or trifluoroethylamine (TFEA), wherein at least one reaction step takes place in a microreactor that is comprising or is made of SiC-microreactor, the processes can be efficiently combined in that HCFC-133a produced by using a microreactor, may preferably advantageously serve as starting material and/or intermediate material in the manufacture of TFEA. The HCFC-133a and/or the TFEA can be easily, by a method with only low energy consumption, purified and/or isolated, and preferably the process for purifying and/or isolating does not require a distillation. Advantageously, the separation from excess hydrogen fluoride (HF) and catalyst can easily take place in an energy-saving manner by phase separation.
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- Reactions of antimony compounds with fluorine gas by thermogravimetric and differential thermal analyses and X-ray diffraction analysis
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Antimony is one of the key fission products in the reprocessing of spent nuclear fuel by the fluoride volatility method because of the high volatility of antimony fluorides. Since the fluorination reaction of antimony compounds is not well understood, the reaction behavior of antimony compounds with F2 was investigated by thermogravimetric and differential thermal analyses and X-ray diffraction analysis in this study. The target antimony compounds were antimony metal, SbF3, Sb2O3, Sb2O4, and Sb2O5. The fluorination reaction of antimony metal started at 150 °C, and the fluorination product was SbF3. SbF3 volatilized completely by the reaction with F2 above 190 °C; it was considered that volatile SbF5 was formed by the reaction with F2. In the series of fluorination of the antimony oxides, Sb2O3, Sb2O4, and Sb2O5, they started to react with F2 and volatilize at 330 °C as SbF5. During the fluorination of Sb2O3, Sb2O4 was formed temporarily in the course of the reaction. Oxygen released from the fluorination reaction of a part of Sb2O3 would oxidize remained Sb2O3 to Sb2O4. The reaction mechanism for the fluorination of antimony compounds obtained in this study is applicable to evaluate the transfer of antimony in the reprocessing process of the fluoride volatility method.
- Watanabe, Daisuke,Akiyama, Daisuke,Sato, Nobuaki
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- Crystal structures of phases observed in [H3O]+/M2+/[SbF6]?system (M?=?Mg, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pd, Cd)
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The reactions between the MO (M?=?Be, Mg, Ca, Sr, Ti, V, Nb, Mn, Ni, Cu, Pd, Zn, Hg, Sn, Pb) and SbF5in liquid aHF were investigated. Reactions with the MO (M?=?Mg, Ni, Cu and Zn) yielded H3OM(SbF6)3compounds. Both BeO and PdO didn't show any sign of reactivity meanwhile MO (M?=?V, Nb, Ti) gave products with M in oxidation state higher than two. The rest of the MO (M?=?Ca, Sr, Mn, Hg, Sn, Pb) formed mixtures of M(SbF6)2, H3OSbF6and/or H3OSb2F11. Reactions between H3OSbF6and M(SbF6)2(M?=?Fe, Co, Ni) also gave H3OM(SbF6)3compounds, meanwhile similar attempts with H3OSbF6and M(SbF6)2(M?=?Ca, Mn, Pd, Ag, Cd, Sn) to prepare [H3O]+/M2+/[SbF6]?salts failled. However, slow crystallizations of H3OSbF6and M(SbF6)2(M?=?Mn, Pd, Cd) mixtures resulted in the single crystal growth of new (H3O)3M(SbF6)5phases which crystal structures are not isotypic. Similar procedure with H3OSbF6/Cr(SbF6)2mixture resulted in few light orange crystals of (H3O)3[CrIV(SbF6)6](Sb2F11)·HF. Its crystal structure determination showed the presence of discrete [CrIV(SbF6)6]2?units where each of Cr atoms is found in a homoleptic coordination of six SbF6groups.
- Mazej, Zoran,Goreshnik, Evgeny
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- The first example of a mixed valence ternary compound of silver with random distribution of Ag(i) and Ag(ii) cations
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The reaction between colourless AgSbF6 and sky-blue Ag(SbF6)2 (molar ratio 2:1) in gaseous HF at 323 K yields green Ag3(SbF6)4, a new mixed-valence ternary fluoride of silver. Unlike in all other Ag(i)/Ag(ii) systems known to date, the Ag+ and Ag2+ cations are randomly distributed on a single 12b Wyckoff position at the 4ˉ axis of the I4ˉ3d cell. Each silver forms four short (4 × 2.316(7) ?) and four long (4 × 2.764(6) ?) contacts with the neighbouring fluorine atoms. The valence bond sum analysis suggests that such coordination would correspond to a severely overbonded Ag(i) and strongly underbonded Ag(ii). Thorough inspection of thermal ellipsoids of the fluorine atoms closest to Ag centres reveals their unusual shape, indicating that silver atoms must in fact have different local coordination spheres; this is not immediately apparent from the crystal structure due to static disorder of fluorine atoms. The Ag K-edge XANES analysis confirmed that the average oxidation state of silver is indeed close to +1 1/3. The optical absorption spectra lack features typical of a metal thus pointing out to the semiconducting nature of Ag3(SbF6)4. Ag3(SbF6)4 is magnetically diluted and paramagnetic (μeff = 1.9 μB) down to 20 K with a very weak temperature independent paramagnetism. Below 20 K weak antiferromagnetism is observed (Θ = -4.1 K). Replacement of Ag(i) with potassium gives K(i)2Ag(ii)(SbF6)4 which is isostructural to Ag(i)2Ag(ii)(SbF6)4. Ag3(SbF6)4 is a genuine mixed-valence Ag(i)/Ag(ii) compound, i.e. Robin and Day Class I system (localized valences), despite Ag(i) and Ag(ii) adopting the same crystallographic position.
- Mazej, Zoran,Micha?owski, Tomasz,Goreshnik, Evgeny A.,Jagli?i?, Zvonko,Ar?on, Iztok,Szyd?owska, Jadwiga,Grochala, Wojciech
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p. 10957 - 10968
(2015/06/25)
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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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p. 8504 - 8523
(2010/12/18)
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- Apparently regular octahedral coordination of Ag(II) in If 6[Ag(SbF6)3]
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The crystal structure of IF6[Ag(SbF6)3] has been determined by X-ray single crystal and X-ray powder diffraction analysis. The structure consists from [Ag(SbF6)3] - chains and [IF6]+ cations placed between them. Ag2+ is found in regular octahedral coordination of six fluorine atoms [Ag-F = 6 × 2.170(12) A]. EXAFS analysis of JahnTeller distortions in IF6[Ag(SbF6)3] shows that Ag2+ surrounding is elongated octahedral at room temperature. EXAFS signals are fitted with four short and two long Ag-F distances [4 × 2.11(1) A 2 × 2.40(2) A]. This result is in apparent contradiction with X-ray diffraction studies where the [AgF6] moiety appears to be a regular octahedra. The Raman spectrum of IF6[Ag(SbF 6)3] is in agreement with the presence of regular IF 6 and deformed SbF6 groups.
- Mazej, Zoran,Goreshnik, Evgeny,Arcon, Iztok,Logar, Natasa Zabukovec,Kaucic, Venceslav
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p. 224 - 229
(2010/06/12)
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- Development and implementation of industrial technologies for synthesis of fluorine compound with the application of elemental fluorine
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A survey is given on the application of elemental fluorine in chemical plants and research centers of Russian Federation.
- Pashkevich,Barabanov,Maksimov
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p. 1142 - 1148
(2009/12/01)
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- The XeCl+ ion: [XeCl]+[Sb2F11]-
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Chlorine-fluorine exchange in XeF+ leads to the orange crystalline salt [XeCl]+[Sb2F11]- (see structure), which is stable below -10°C. Thus, the number of known noble gas monohalogen cations is now three and, as calculations show, is approaching the theoretically possible limit. The synthesis of other such compounds - with the exception of ArF+, which remains a formidable task - seems unlikely.
- Seidel, Stefan,Seppelt, Konrad
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p. 4225 - 4227
(2007/10/03)
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- Superelectrophilic tetrakis(carbonyl)palladium(II)- and -platinum(II) undecafluorodiantimonate(V), [Pd(CO)4] [Sb2F11]2 and [Pt(CO)4][Sb2F11]2: Syntheses, physical and spectroscopic properties, their crystal, molecular, and extended structures, and density functional calculations
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The salts [M(CO)4][Sb2F11]2, M = Pd, Pt, are prepared by reductive carbonylation of Pd[Pd(SO3F)6], Pt(SO3F)4 or PtF6 in liquid SbF5, or HF-SbF5. The resulting moisture-sensitive, colorless solids are thermally stable up to 140°C (M = Pd) or 200°C (M = Pt). Their thermal decompositions are studied by differential scanning calorimetry (DSC). Single crystals of both salts are suitable for an X-ray diffraction study at 180 K. Both isostructural salts crystallize in the monoclinic space group P21/c (No. 14). The unit cell volume of [Pt(CO)4][Sb2F11]2 is smaller than that of [Pd(CO)4][Sb2F11]2 by about 0.4%. The cations [M(CO)4]2+, M = Pd, Pt, are square planar with only very slight angular and out-of-plane deviations from D4h symmetry. The interatomic distances and bond angles for both cations are essentially identical. The [Sb2F11]- anions in [M(CO)4]-[Sb2F11]2, M = Pd, Pt, are not symmetry-related, and both pairs differ in their Sb-F-Sb bridge angles and their dihedral angles. There are in each salt four to five secondary interionic C- -F contacts per CO group. Of these, two contacts per CO group are significantly shorter than the sum of the van der Waals radii by 0.58 - 0.37 A. In addition, structural, and spectroscopic details of recently synthesized [Rh(CO)4] [Al2Cl7] are reported. The cations [Rh(CO)4]+ and [M(CO)4]2+, M = Pd, Pt, are characterized by IR and Raman spectroscopy. Of the 16 vibrational modes (13 observable, 3 inactive) 10 (Pd, Pt) or 9 (Rh), respectively, are found experimentally. The vibrational assignments are supported by DFT calculations, which provide in addition to band positions also intensities of IR bands and Raman signals as well as internal force constants for the cations. 13C NMR measurements complete the characterization of the square planar metal carbonyl cations. The extensive characterization of [M(CO)4] [Sb2F11]2, M = Pd, Pt, reported here, allows a comparison to linear and octahedral [M(CO)n][Sb2F11]2 salts [M = Hg (n = 2); Fe, Ru, Os (n = 6)] and their derivatives, which permit a deeper understanding of M-CO bonding in the solid state for superelectrophilic cations with [Sb2F11]- or [SbF6]- as anions.
- Willner,Bodenbinder,Broechler,Hwang,Rettig,Trotter,Von Ahsen,Westphal,Jonas,Thiel,Aubke
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p. 588 - 602
(2007/10/03)
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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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- Preparations and the crystal structure of SbF3*4SbF5
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3SbF3*4SbF5 has been prepared from the reaction of SbF3 with a large excess of SbF5 anf from the reaction of WF5 with SbF5 in Genetron 113.An X-ray structure determination has shown that the compound crystallizes in the monoclinic space group P21/c with a = 8.547(10), b = 13.521(8), c = 19.551(12) angstroem, β = 100.3(1) deg, Z = 4 with the final residual indices of R = 0.0486 and Rw = 0.0526 for 4274 unique reflections.If only Sb-F distances of less than 2.1 angstroem are considered the structure can be viewed in terms of the arrangement (SbF2+)(SbF2+)2(SbF6-)4.A Raman spectrum from single crystals of the compound is reported.Key words: X-ray structure, antimony, fluoride, Raman.
- Fawcett, John,Holloway, John H.,Russell, David R.,Edwards, Anthony J.,Khallow, Khalaf I.
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p. 2041 - 2046
(2007/10/02)
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- Preparations and Spectroscopic Characterization of Fluoro(trifluoromethylsulfenyl)phosphonium Salts, CF3SPH2F(+)MF6(-) (M = As, Sb)
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The preparations of the title compounds are reported.The species have been characterized by multinuclear (1H, 13C, 19F, 31P) NMR techniques.Their decomposition, leading mainly to PH2F2(+)MF6(-), was also studied.The Raman spectrum of CF3SPH2F(+)AsF6(-) is presented. - Keywords: Fluoro(trifluoromethylsulfenyl)phosphonium Salts, NMR Spectra, Raman Spectra
- Minkwitz, Rolf,Liedtke, Andreas
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p. 1263 - 1267
(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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- Preparation and Characterization of the Uranyl Fluoride-Antimony Pentafluoride Adduct, UF2O2*4SbF5
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When UF4O*2SbF5 is treated with anhydrous hydrogen fluoride a slow reaction in solution takes place.Investigation of this reaction and those of UF4O-SbF5-HF solutions on standing have shown that, in both cases, UF6 and a new uranyl fluoride derivative, UF2O2*4SbF5, are produced.
- Holloway, John H.,Laycock, David,Bougon, Roland
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p. 1635 - 1636
(2007/10/02)
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- Gas-Phase Chemiionization Reactions of Antimony Pentafluoride
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Using crossed molecular beams, we have studied the reactions of SbF5 and its polymers with organic halides (RX).Monomer SbF5 reacts with some RX species to produce R(1+) + SbF5X(1-).Dimer reacts with a wider variety of RX species to produce R(1+) + SbF6(1-) + SbF4X.Unless R(1+) is particularly subject to cleavage, only the parent R(1+) is observed; this indicates that the product is formed with only a small amount of internal energy.
- Lee, L.,Russel, J.A.,Su, R.T.M.,Cross, R.J.,Saunders, M.
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p. 5031 - 5034
(2007/10/02)
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