[en] Electron microprobe analyses and the refinement of the crystal structure indicate, that sylvanite, AuAgTe₄, from Baia de Aries (=Offenbanya), Romania, has a stoichiometric composition and an ordered crystal structure (a-8.95(1) A, b=4.478(5) A, c=14.62(2) A; β=145.35(5)supo; Z-2; space group P2/c-Csub(2h)⁴). The Au atom is surrounded by six Te atoms in a [4+2] coordination as characteristic for oxidation state III. Around the Ag atom (oxidation state I) are also six Te atoms, but arranged in a [2+2+2] coordination. Via common edges the AuTe₆ and AgTe₆ polyhedra build up 'sheets' parallel to (100). These 'sheets' are combined to a network of Te₂ dumbbells (Te-Te=2.82 A). (Author)

[en] The crystal structure redetermination of krennerite (a=16.58, b=8.849, c=4.464 A; Z=8; space group: Pma 2-Csub(2v)⁴) with 1063 X-ray data yielded an R-value of 5.8%. Within the structure, there are three crystallographically different noble metal positions. Two of them are statistically occupied by Au and Ag atoms (ratios of 75:25 and 50:50, respectively) and one position by Au atoms only. The (Au, Ag) atoms are surrounded by six Te atoms with a [2+2+2] coordination. The Au atom has a [4+2] coordination built up by six Te atoms. These three different coordination polyhedra are linked via common Te-Te edges to rugged 'sheets' parallel to (010). These 'sheets' are connected to a framework by four crystallographically different Te atoms - combined to one Te₃ group and two Te₂ dumbbells (with Te-Te,2.9 A). A fifth Te atom is only surrounded by (Au, Ag) and Au atoms. According to these different structural elements the crystal chemical formula may be written as (Ausub(2-x)Agsub(x))Ausubx[Te₃][Te₂]₂[Te]; x nearly equal to 0.8. (Author)

[en] We report herein the synthesis of the first vinylogous BDT-TTP, DTEDT, which contains one 2,2'-ethanediylidenebis(1,3-dithiole). Furthermore, we have found that the present donor produces a superconducting Au(CN)₂ salt, as well as many metallic cation radical salts stable to liquid helium temperature. (orig.)

[en] The fundamental study Au recovery from potassium gold cyanide(PGC) solution was conducted using photochemical reaction on TiO2. The reduction-adsorption rate of Au(III) on TiO2 in standard Au(III) solution was slower than that of Ag(I) in standard Ag(I) standard solution at same condition. The removal reaction of cyanide in PGC solution was carried out using the radical reaction of H2O2 and S2O8 2-. The H2O2 process, whose removal rate is rather slower, is simpler than S2O8 2- process. Adsorption rate was much improved by adding methanol as a hole scavenger at the photochemical reaction of Au(III) with TiO2 in PGC solution. The pH effect on reduction-adsorption rate of Au(III) ions on TiO2 by photochemical reaction in PGC solution was faster in basic solution

[en] 11 new alkalichalcogenoaurates(I) and (III) were found and their crystal structures determined from single crystal X-ray data measured on a four-circle diffractometer (MoKα-radiation). Na₃AuSe₂ (Pccn, Z=4, 1045.6(2) pm, b=805.80) pm, c=728.20) pm) is of a new structure type characterized by dumbbell shaped complex anions (Se-Au-Se)^3-. K₃AuSe₂ (R3-bar c, Z=6, a=890.30 pm, c=1809(2) pm) is characterized by the formation of linear complex anions (Se-Au-Se)^3-. RbAuSe (Cmcm, Z=4, a=678.2(3) pm, b=833.2(2) pm, c=674.4(2) pm) is characterized by infinite anionic zig-zag chains. The polyselenoaurate(I) Cs₂Au₂Se₃ (C2/c, Z=4, a=976.9(5) pm, b=1344(1) pm, c=717.8(3) pm, β =90.69(2) degree ) is characterized by infinite anionic chains (Au₂Se₃)^2-. A different chaintype involving triselenide chains is found in CsAuSe₃ (C2/c, Z=4, a=646.60 pm, b=1375(1) pm, c=762.4(5) pm, β=112.16(2) degree , characterized by infinite anionic chains, (AuSe₃)^-. CsAu₃S₂, RbAu₃Se₂and CsAu₃Se₂ (P3-bar m1, Z=1, CsAu₃S₂: a=619.2(1) pm, c=508.0(2) pm; RbAu₃Se₂: a=611.2(4) pm, c=522.4(6) pm; CsAu₃Se₂: a=628.1(1) pm, c=520.5(1) pm) are isostructural and are characterized by the formation of corrugated chalcogenoaurate layers (Au₃X-2)^-. Another structure type which is built up by corrugated layers is represented by Cs₄Au₆S₅ (P3m1, Z=1, a=1024.3(3) pm, c = 529.0(2) pm). These (Au₆S₅)^4- layers are consisted of condensed Au₁₂S₁₂-rings. Rb₄Au₆S₅ (P6-bar2c, Z=2, a=998.3(6) pm, c=995.0(7) pm) contains discrete anionic clusters (Au₆S₅)^4- of trigonal bipyramidal shape. Na₅Au(III)Se₁2 (P2₁, Z=2, a=714.5(1) pm, b=1679.0(6) pm, c=829.1(1) pm, β=107.13(1) degree is characterized by the formation of discrete polyanionic moieties [Au(III)Se₁2]^5-. (author)

[en] Aurocyanides of the following metal cations have been prepared: Ag, Hg(II), Ga, Fe(III), Tl(I), Bi, Pb, Mn(II), Ni, Zn, Cu(II), Cd, In, and Co(II). Most of the aurocyanides are of the type M[Au(CN)₂]_x where M is the metal cation and x its valence. However, under some conditions mixed aurocyanides containing K may be formed, such as KCo[Au(CN)₂]₃. Only Ag and Hg(II) form aurocyanides which are sufficiently insoluble for the potentiometric determination of the aurocyanide anion. The diffraction patterns of the various aurocyanides are reported. 12 refs., 16 tabs

[en] We measured XPS and UPS spectra of gold clusters with 55 atoms, embedded in an electrically isolating phosphine matrix, and of gold-phosphine, from which the clusters were chemically derived. Compared to the spectra of bulk gold the valence band spectrum and the core level spectra of the clusters showed shifts of the peaks and the fermi level to higher binding energies. The shift of the peaks could qualitatively be interpreted by a final state effect. We succeeded in a separation of bulk and surface contributions to the core level spectra and in a reasonable quantitative analysis of the valence band spectrum of the clusters. The Au 4f core level spectrum of gold-phosphine showed two peaks at 1.5 eV higher binding energies than the corresponding peaks of the clusters. (orig.)

[en] Moessbauer effect spectroscopy has been applied to the study of three polynuclear gold cluster compounds. The resulting information on the local vibrational density of states has been compared to several models which take the finite size of the particles into consideration. 188 refs.; 34 figs.; 103 schemes; 8 tabs

[en] Bis naphthyl based thiol stabilized gold nanoparticles were synthesized by the chemical reduction of corresponding precursor, obtained from Au(III) salt with thiol ligand 4. The organo thiol ligand 4 were prepared from 1,1/sup '/-binaphth-2,2/sup '/-ol in three steps. Furthermore, the photophysical activity of these Au-NPs was also determined. (author)

[en] The observed energy shifts of the Mn 3p core-level in the surface compounds of c(2x2)MnCu and c(2x2)MnAu is larger than the ones calculated by theoretical models. This additional shift is a hint for magnetic behaviour in the two studied systems