(Triphenylarsine)gold(I) Complexes: Synthesis of an Oxonium Salt and Redistribution of the Arsine Ligands

The reaction of [(Ph3As)AuCl] with Ag2O in the presence of NaBF4 in tetrahydrofuran affords three products, identified as [(Ph3As)4Au]BF4 (40.3%), [(Ph3As)2Au]BF4 (16.4%) and {[(Ph3As)Au]3O}BF4 (17.3%). The properties of the main product agree well with recent literature data. The other two compounds are new and have been identified by their analytical, spectroscopic, and crystallographic data. The structures are isomorphous with those of the analogous Ph3P complexes. Variations in the stabilities are discussed in terms of kinetic and thermodynamic effects.

Preparation and Structure of Poly(gold)telluronium Salts

Tris[(triphenylphosphine)gold(I)]telluronium tetrafluoroborate (1) was prepared from the corresponding oxonium salt and bis(t-butyldimethylsilyl)tellurium in dichloromethane at -78°C. The product forms yellow crystals, thermally stable to 125°C. It was identified by standard analytical and spectroscopic techniques, including a single crystal X-ray diffraction study. In the crystal lattice, the cations form tellurium-capped triangles of gold, which are associated into dimers through short intermolecular Au -Au contacts, resembling those in the corresponding sulfur and selenium compounds. - The reaction of (t-BuMe2Si)2Te with four equivalents of [(Ph3P)Au]BF4 in tetrahydrofuran at -78°C gives a tetranuclear compound, {[(Ph3P)Au]4Te}2+ 2 BF4- (2) which differs from 1 in its analytical and spectroscopic data. Its structure could not be determined, but it is assumed that the dications have a square pyramidal geometry

Zum System Wasser—Fluorwasserstoff: Phasenverhalten und Kristallstruktur von 2 D2O• 3 DF, einer deuterierten Verbindung ohne protoniertes Analogon / Concerning the System Water—Hydrogen Fluoride: Phase Behaviour and Crystal Structure of 2 D2O· 3 DF, a Deuterated Compound Lacking the Protonated Analogue

The melting diagram of the quasibinary system D2O— DF was determined by low-temperature DTA and X-ray powder diffraction. It was found to be largely similar to that of the corresponding non-deuterated system H2O—HF with the striking exception of an additional phase with a composition of its own, 2D2O· 3 DF, and stable between ca. —78 and —71°C. Its structure, determined from single-crystal MoKā diffractometer data at —150°C, is rhombohedral (space group R3c, Z = 6, a = 769.9, c = 1242.1 pm) and strongly related to that of NH, · 4 HF or NH4[F(HF)3] with also seven H (as to be compared to D) and five non-H (non-D) atoms per formula unit. But with the O atom involved in four hydrogen bonds, one O · · · O and three O · · · F. at distances of 273.9 and 259.5 pm, respectively, the compound appears to be a molecular adduct rather than an oxonium salt. The D atoms in the hydrogen bonds are distributed over two positions each. — The remaining intermediary phases of the deuterated system, i. e. D2O · DF, D2O· 2 DF and D2O · 4 DF, are isotypic to their protonated counterparts of known crystal structure. For D2O · DF and D2O-2 DF these results from powder patterns were confirmed by two more single-crystal studies. The ionic structures — D3OF and D3O[F(DF)], respectively — show no distinctive effect of the H/D substitution even on details of the interatomic geometries.

Fluoride und Fluorosäuren, VII [1]. Kristallstrukturen von Säurehydraten und Oxoniumsalzen, XXII [2]. Hydratbildung der Trifluoressigsäure sowie Strukturen eines Monohydrats und eines Tetrahydrats [3]. / Fluorides and Fluoro Acids, VII [1] Crystal Structures of Acid Hydrates and Oxonium Salts, XXII [2]. Hydrate Formation of Trifluoroacetic Acid and Structures of a Monohydrate and a Tetrahydrate [3]

The liquidus and solidus lines of the quasi binary system CF3COOH-H2O were determined by low temperature difference thermal analysis and the resulting phase relations controlled by X-ray powder diffraction. Formation of a monohydrate and a tetrahydrate, melting congruently at -43 and -16 °C, respectively, is confirmed. In addition a metastable form of the monohydrate and a low temperature form of the tetrahydrate, stable below -47 °C, are indicated. The crystal structures of the stable high temperature forms were determined. From these the monohydrate (tetragonal, space group I42d, Z = 16) is a true acid hydrate, CF3COOH-H2O, and the tetrahydrate (triclinic, P1̅, Z = 2) a hydrated oxonium salt, (H5O2)+[H(CF3COO)2]- · 6H2O.