- Synthesis and structure of MII[AuF4]2 (MII = Cd, Hg)
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Cd[AuF4]2 and the isotypic compound Hg[AuF4]2, both are yellow, crystallize tetragonal in the space-group P4/mcc-D24h (No. 124) with a = 575.0/575.6 pm, c = 1034.8/ 1042.3 pm and Z = 2. The single-crystals were obtained by solid-state reactions in goldtubes.
- Bialowons,Mueller
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- On the crystal structure of La[AuF4]3, the final link in the series M[AuF4]3-xFx (x = 0, 0.5 and 1)
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Yellow La(AuF4)3 was prepared for the first time in form of single crystals and investigated by X-ray methods. It crystallizes in space group R3c-D3d6 (Nr. 167) with a = 1056.2(2) pm, c = 1633.7(8) pm, Z = 6. Johann Ambrosius Barth 1996.
- Graudejus,Mueller
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- Improvement of photocatalytic activity of titanium (IV) oxide by dispersion of Au on TiO2
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The photocatalytic oxidation of organic compounds in an aqueous solution containing a suspension of titanium(IV) oxide is a comparatively new method for removing impurities from water. TiO2 samples were prepared by two procedures, and their catalytic activities in the degradation of 1,4-dichlorobenzene were compared to samples of commercial TiO2. It was found that the dispersion of gold onto the surface of the oxide powders greatly increased their photocatalytic activity.
- Gao, Y.-M.,Lee, W.,Trehan, R.,Kershaw, R.,Dwight, K.,Wold, A.
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- A green paramagnetic gold fluoride - Sn1-xAuxF4?
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Green single crystals were obtained by heating (Au-tube, 450°-500°C) a mixture of SnF2 and AuF3 (Sn:Au = 1:1) which correspond to the SnF4-type [2, 3] (two single crystals, A: 762 Io, R1 = 2.4%; B: 1591 Io, R1 = 1.2% (SHELXL=93); I4/mmm (No. 139); B: a = 404.8(1) pm, c = 796.4(1) pm, c/a = 1.97, zF2 = 0.2354). Due to atom absorption and Moessbauer measurements the crystals contain Au. The compound is paramagnetic and follows the Curie-Weiss law (14.7-251.3 K, θ = -12K, μ/μB = 1.55). ESR-experiments confirm that Au is surrounded by 6 F- according to Sn in SnF4 (2 short (187.5 pm) and 4 longer (202.4 pm) distances). The observed Moessbauer spectra could not be interpreted yet, but they don't correspond to any known. Johann Ambrosius Barth 1996.
- Bork,Hoppe,Hofstaetter,Scharmann,Wagner
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- Synthesis, crystal structure, and thermal properties of [Ir(NH 3)5Cl][AuCl4]Cl
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A double complex salt [Ir(NH3)5Cl][AuCl 4]Cl is synthesized and studied by X-ray diffraction. Its crystal data follows: a = 17.369(4) ?, b = 7.7990(16) ?, c = 11.218(2) ?, V = 1430.5(5) ?3, space group C2/m, Z = 4, ρ calcd = 3.19 g/cm3, R = 0.0447. Thermolysis in air, hydrogen, and helium is studied. Copyright
- Plyusnin,Baidina,Shubin,Korenev
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p. 1834 - 1840
(2008/10/09)
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- Synthesis and structure of Tetrafluoroaurates(III), TlF2[AuF4], M2F[AuF4]5 (M = Y, La, Bi), Sm[AuF4]3 with an appendix on Sm[AuF4]2
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In the system MF3/AuF3 the structures of several yellow Tetrafluoroaurates(III) have been determinated. TlF2[AuF4] crystallizes tetragonal, space group P41212 - D44 (Nr. 92) with a = 573.17(4) pm, c = 2780.4(3) pm, Z = 8; M2F[AuF4]5 (M = Bi, La) tetragonal, space group P41212 - D44 (Nr. 92) with a = 822.89(5) pm, c = 2557.1(3) pm, Z = 4 (Bi); with a = 836.80(3) pm, c = 2602.2(2) pm, Z = 4 (La); Y2F[AuF4]5 monoclin, space group P2/n - C2h4 (Nr. 13) with a = 1188.9(3) pm, b = 797.4(2) pm, c = 895.7(3) pm, β = 89.18(3), Z = 4 and Sm[AuF4]3 trigonal, space group R3c - D3d6 (Nr. 167) with a = 1034.5(1) pm, c = 1614.1(3) pm, Z = 6. All these yellow crystals have been obtained by solid state reactions in autoclaves or sealed goldtubes.
- Fitz,Mueller
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p. 126 - 132
(2008/10/08)
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- Rh2Cl2(CO)4 adsorbed and tethered on gold powder: IR spectroscopic characterization and olefin hydrogenation activity
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Catalysts were prepared by adsorbing Rh2Cl2(CO)4 directly on gold powder or on gold that contained the tethered ligands 2-(diphenylphosphino)ethane-1-thiol (DPET) or methyl 2-mercaptonicotinate (MMNT). Infrared (IR) studies (diffuse reflectance infrared Fourier transform (DRIFT)) of the catalyst Rh-Au prepared by adsorbing Rh2Cl2(CO)4 directly on Au indicate that a RhI(CO)2 species is present. IR studies of Rh-DPET-Au suggest that tethered cis-Rh(DPET)(CO)2Cl is the major species at relatively high Rh2Cl2(CO)4 loadings, but trans-Rh(DPET)2(CO)Cl is observable at low Rh2Cl2(CO)4 loadings. Spectral investigations of the catalyst Rh-MMNT-Au prepared by adsorbing Rh2Cl2(CO)4 on MMNT-Au suggest that tethered [cis-Rh(MMNT)2(CO)2]+Cl- and (or) Rh(MMNT)(CO)2Cl are the major species at low Rh2Cl2(CO)4 loadings, while a new unidentified species predominates at high Rh2Cl2(CO)4 loadings. All three catalysts are active 1-hexene hydrogenation catalysts under the mild conditions of 40°C and 1 atm of H2; they are much more active than Au powder or Rh2Cl2(CO)4 in solution. Of the three catalysts, Rh-Au is the most active with a maximum turnover frequency (TOF) of 800 mol H2 per mol Rh per min while its turnover (TO) is 29 600 mol H2 per mol Rh during a 2-hour run. Under the conditions of 1-hexene hydrogenation, the catalysts lose their CO ligands. Thus, it appears that a form of Rh metal on Au is the catalytically active species.
- Gao,Angelici
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p. 578 - 586
(2007/10/03)
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- Synthesis and structure of MII[AuF4]2 with MII = Ni, Pd
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Yellow Ni[AuF4]2, obtained as single crystals by solvothermal synthesis in anhydrous HF crystallizes monoclinic, isotypic to M[AuF4]2 (M = Mg, Zn) [1], space group P21/c-C52h (No. 14) with a = 550.4, b = 546.0, c = 1083.1 pm and β = 109.47°. In order to get better comparison to Pd[AuF4]2 it will be described in the space group P21/n with a = 550.4 pm, b = 546.0 pm, c= 1038.2 pm, β = 100.47° and Z = 2. Green Pd[AuF4]2, prepared by heating a mixture of PdF2 and AuF3 in sealed Au-tubes crystallizes also monoclinic, space group P21/c (setting P21/n with a = 519.79 pm, b = 1095.7 pm, c = 555.7 pm, β = 89.93° and Z = 2), but it is not isotypic to Ni[AuF4]2.
- Bialowons,Mueller
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p. 434 - 438
(2008/10/09)
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- Lewis-acid-base-reactions of gold trihalides with bismuth trihalides - Synthesis and structures of AuBiX6 (X = Cl, Br)
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Gold trihalides AuX3 (X = Cl, Br) react with bismuth trihalides in sealed glass ampoules to the 1:1 adducts AuBiX6 (X = Cl, Br). AuBiCl6 is obtained by a chemical transport reaction at 220 °C, whereas AuBiBr6 was synthesized by solvothermal reaction in SiBr4 at 1.50 °C. Both compounds crystallize triclinic, space group P1?, Z = 4, AuBiCl6: a = 698.3(4) pm; b = 1009.3(5) pm; c = 1381(1) pm; α = 104.98(5)○; β = 94.73(5)○; γ = 110.06(3)○; V = 867(1) · 106 pm3. AuBiBr6: a = 735.7(4) pm; b = 1055.7(5) pm; c = 1445(1) pm; α = 104.88(5)○; β = 94.25(5)○; γ = 110.18(4)○; V = 1001(1) · 106 pm3. The structures are build formally of square-planar [AuX4]- and chains of edge-connected ([BiX4/2]+)n units. Since each Bi ion is surrounded by eight halogenide ions in a square-antiprismatic form, the structure can alternatively be described as consisting of chains of edge sharing ([BiX4X4/2]3-)n antiprisms connected by Au3+ ions.
- Beck,Wagner
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p. 1810 - 1814
(2008/10/09)
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- Valence of Au in AuTe2 and AuSe studied by x-ray absorption spectroscopy
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The gold compounds AuTe2 and AuSe contain Au atoms in two different chemical surroundings. In the literature these different coordinations have been associated with a difference in valency of the Au atoms. In this paper the occupation of the 5d shell in AuSe and AuTe2 is deduced from a study of the 4f → 5d X-ray absorption edge. A comparison is made with the absorption edges of Au, AuCl and AuCl3. The results show that only AuCl3 has Au atoms in a valence state of III, and that the Au atoms in AuTe2 and AuSe are all in the same monovalent state I, independent of their chemical environment.
- Ettema, A. R. H. F.,Stegink, T. A.,Haas, C.
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p. 211 - 214
(2008/10/08)
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- Bis(carbonyl)gold(I) undecafluorodiantimonate(V), [Au(CO)2][Sb2F11]: Synthesis, vibrational and13C NMR study, and the molecular structure of Bis(acetonitrile)gold(I) hexafluoroantimonate(V), [Au(NCCH3)2][SbF6]
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The synthesis of the bis(carbonyl)gold(I) salt, [Au(CO)2][Sb2F11], is achieved in a two-step procedure: The reduction of gold(III) fluorosulfate, Au(SO3F)3, in HSO3 F to give Au(CO)SO3F as an intermediate, followed by solvolysis in liquid antimony(V) fluoride in the presence of carbon monoxide. The use of 13CO or C18O permits the synthesis of the corresponding isotopically labeled salts. The compound is thermally stable up to 130 °C. The cation has D∞h symmetry, and all seven fundamentals, three Raman and four IR active modes, are observed. A normal coordinate analysis (NCA) and general valence force-field (GVFF) calculations are carried out and allow comparison to the isoelectronic and isosteric molecular species Hg(CN)2 and [Au(CN)2]. The near absence of gold to carbon π-back donation in [Au(CO)2+ is manifested in strong carbon-oxygen bonds and consequently rather weak gold-carbon bonds, reflected in the highest CO-stretching frequencies so far observed for a metal carbonyl derivative with 254 (v1) and 2217 (v3) cm-1 and a stretching force constant of 20.1 × 102 Nm-1. In the 13C NMR spectrum a single-line resonance at 174 ppm is attributed to [Au(CO)2]+, while the [Au]+ and The coalescence temkperature is solvent dependent, 325 K in HSO3 F and 395 K in the more dilute HSO3F/SbF5 mixture. Attempts to recrystallize [Au(CO)2][Sb2F11] From acetonitrile resullt in the formation of single crystals of [Au(NCCH3)2] [SbF6] instead. The compound crystallizes in a cubic unit cell, space group Pa3?, with a = 10.250 (2) A? and A = 4. The structure was determined by Pattersn and Fourier methods and refined by least-squares techniques to R = 0.023 and Rw = 0.024 for 147 reflections with 1> 3σ(I). The crystal contains linear [Au(NCCH2]+ cations and octahedral [SbF6- anions, with normal dimensions.
- Willner,Schaebs,Hwang,Mistry,Jones,Trotter,Aubke
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p. 8972 - 8980
(2007/10/02)
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- Relativistic effects in gold chemistry. 4. Gold(III) and gold(V) compounds
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Hartree-Fock (HF) calculations of the electronic structure and bonding in gold(III) and gold(V) compounds (AuH3, AuF3, AuCl3, AuH4-, AuF4-, AuCl4-, AuBr4-, AuI4-, AuF6-, Au2H6, Au2F6, Au2Cl6) have been carried out. Non-relativistic and relativistic pseudopotentials were applied using a [Xe4f14]-core definition for the gold atom, however, including the 5s and 5p electrons in the valence space. All bond distances and angles were optimized. M?ller-Plesset (MP2-4) calculations on the stability of gold(III) halide complexes were carried out to study the effects of electron correlation at the nonrelativistic and relativistic level of the theory. The relativistic effects in the Au-L bond are analyzed. Relativistic changes in Au(III)-ligand bond distances are calculated to be small compared to those in Au(I) compounds. However, relativistic changes in Au(III)-ligand stretching force constants are very large and of comparable magnitude to that in Au(I) compounds. The preference of the oxidation state III in gold is found to be influenced considerably by relativistic effects and is dependent on the electronegativity of the ligand. The conclusions drawn from previously published HF results (J. Am. Chem. Soc. 1989, 111, 7261) on the stability of AuL4- (L = F, Cl, Br, I) are confirmed by MP2-4 calculations; i.e., the decomposition AuL4- → AuL2- + L2 occurs less easily relativistically than nonrelativistically. Relativistic effects also contribute to the facile decomposition of AuF into Au and AuF3. All calculated AuL3 compounds (L = H, F, Cl) show T-shaped structures as a result of a first-order Jahn-Teller symmetry breaking of the D3h trigonal planar structure into the C2υ, arrangement. A rationalization for the polymeric helix structure of AuF3 is provided. The stability and structure of gold(III) hydride is examined in detail. Multiple scattering Xα calculations were carried out on AuF4-, AuCl4-, AuBr4-, and AuI4- to determine relativistic effects in the nuclear quadrupole coupling constant for 197Au. Au2Cl6 was prepared, and a single-crystal X-ray analysis was carried out to compare with data obtained by the MP2 method (monoclinic, space group P21/c with a = 6.5906 (9) A?, b = 11.007 (2) A?, c = 6.442 (3) A?, Z = 4, 873 reflections, and R = 0.0561).
- Schwerdtfeger, Peter,Boyd, Peter D. W.,Brienne, Stephane,Burrell, Anthony K.
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p. 3411 - 3422
(2008/10/08)
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- Vaporization and vapor complexation in the gold(III) chloride-aluminum(III) chloride system
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The vapors over solid gold(III) chloride and the vapor-phase equilibria of the gold(III) chloride-alummum(III) chloride binary system have been investigated spectrophotometrically. The thermodynamic functions of the sublimation 2AuCl3(s) = Au2Cl6(g) were determined: ΔHS° = 114.2 ± 1.8 kJ mol-1 and ΔSS° = 160.5 ± 3.3 J mol-1 K-1 (480 3(s) + 1/2Al2Cl6(g) = AuAlCl6(g) with ΔHR° = 59.9 ± 0.8 kJ mol-1 and ΔSR° = 91.5 ± 1.6 J mol-1 K-1 (470 2Cl6(g) pressure the volatility enhancement of AuCl3 is ～300. The electronic absorption spectra of the Au2Cl6(g) and AuAlCl6(g) molecules were interpreted in terms of a distorted square planar geometry of Au(III). Bridged and terminal ligand-to-metal charge-transfer bands were indentified in the spectra.
- Nalbandian,Boghosian,Papatheodorou
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p. 1769 - 1773
(2008/10/08)
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- Studies on gold(II) complexes with hard and soft donor ligands. 3. Complexes with N-(2-pyridylmethyl)-2-mercaptoaniline
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The synthesis and characterization of gold(II) complexes with N-(2-pyridylmethyl)-2-mercaptoaniline (Hpma) are reported. Both mononuclear and dinuclear complexes are isolated by using different synthetic procedures. The solution EPR spectra of the mononuclear complexes Au(pma)X (X = Cl, Br) (1a,b) are identical and consist of four hyperfine lines of equal intensity due to the interaction of the unpaired electron with one 197Au nucleus (I = 3/2). The solution EPR spectra of the dinuclear complexes Au2(pma)X4 (1c,d) exhibiting unsymmetrical seven-line pattern with varying intensities show that the unpaired electron is interacting with two inequivalent 197Au nuclei. A spontaneous dissociation of these mixed-valent Au(II)/Au(III) compounds occurs in nitrobenzene solution, and ultimately a four-line EPR pattern is obtained. The Au(4f) ESCA spectrum of 1c clearly shows the presence of the Au(II) and Au(III) centers. Another dimeric compound [Au(pma)Cl]2 (1e) exhibits only a broad EPR signal in solution. Though the stoichiometries of compounds 1a and 1e are found to be identical, their structural differences are clearly reflected in their solution EPR spectra and cyclic voltammetric results. The electronic spectra of compounds 1a-e exhibit low-energy ligand field transitions in the red and near-infrared (near-IR) regions followed by intense LMCT bands in the visible region. The very small hyperfine coupling originating from the gold in these complexes is strongly indicative of the low metal character of the highest occupied molecular orbital. The large delocalization of the unpaired electron largely accounts for the experimentally observed g values.
- Koley,Nirmala,Prasad,Ghosh,Manoharan
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p. 1764 - 1769
(2008/10/08)
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