Mononuclear Gold Complexes Research Articles

Structures and luminescence of mononuclear and dinuclear base-stabilized gold(I) pyrazolate complexes

The mono- and dinuclear base-stabilized gold(I) pyrazolate complexes, (PPh 3)Au(μ-3,5-Ph 2pz)) ( 1), (TPA)Au(3,5-Ph 2pz), TPA=1,3,5-triaza-7-phophaadamantane ( 2), [(PPh 3) 2Au(μ-3,5-Ph 2pz)]NO 3 ( 3) and [(dppp)Au(μ-3,5-Ph 2pz)]NO 3, dppp=bis(diphenylphosphino)propane ( 4), have been synthesized and structurally characterized. The mononuclear gold(I) complexes 1 and 2 show intermolecular Au⋯Au interactions of 3.1540(6) and 3.092(6) Å, while the dinuclear gold(I) complexes 3 and 4 show an intramolecular Au⋯Au distances of 3.3519(7) and 3.109(2) Å, respectively, typical of an aurophilic attraction. Complexes 1– 4 exhibit luminescence at 77 K when excited with ca. 333 nm UV light with an emission maximum at ca. 454 nm. The emission has been assigned to ligand-to-metal charge transfer, LMCT, based upon the vibronic structure that is observed.

Reactions of Au(CH3)2(acac) on γ-Al2O3: Characterization of the Surface Organic, Organometallic, Metal Oxide, and Metallic Species

The reaction of Au(CH3)2(acac) with the partially dehydroxylated surface of γ-Al2O3 (calcined at 673 K) and the subsequent formation of supported gold clusters upon treatment of the supported species in He at various temperatures and 1 atm were investigated with infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectorscopies, and X-ray absorption near edge structure (XANES). The IR spectra show that Au(CH3)2(acac) reacts readily at room temperature with both surface OH groups and coordinatively unsaturated aluminum sites of the γ-Al2O3 surface, forming supported mononuclear gold complexes and {Al}−acac species (where the braces refer to surface Al sites). EXAFS data demonstrate the formation of mononuclear gold complexes as the predominant surface gold species, confirmed by the lack of Au−Au contributions in the EXAFS spectra. The mononuclear complex is represented as {AlO}2−AuIII(CH3)2, with the Au−O bonding distance being 2.15 Å. Treatment of {AlO}2−AuIII(CH3)2 in He at 323 K and 1 atm led to formation of supported Au(III) oxide in the form of highly dispersed clusters. Further treatment of the samples led to the formation of metallic gold clusters of increasing size, ultimately those with an average diameter of about 30 Å. The {Al}−acac groups were converted to {Al}−acetate groups upon treatment in He at 423 K; further treatment at increasing temperatures removed all the organic ligands from the surface. The results provide the first evidence of the reaction of a metal acetylacetonate complex with an oxide surface that is characterized by essentially all the resultant surface species.

Structure and reactivity of a mononuclear gold-complex catalyst supported on magnesium oxide.

A golden age of catalysis? A structural model of a MgO-supported complex [AuIII(CH3)2{OMg}2] (where the MgO ligands are part of the MgO support) has been established based on distances and coordination numbers determined by EXAFS spectroscopy (see picture). This compound is the precursor of a mononuclear gold complex that catalyzes ethene hydrogenation. For comparison, a family of supported gold clusters was also prepared.

Trifluoromethyl(triphenylphosphine)gold(I)

The title compound, [Au(CF 3 ){P(C 6 H 5 ) 3 )], is the first crystallographically characterized mononuclear gold(I) complex with an Au-CF 3 bond. The Au coordination is nearly linear with P-Au-C 178.56(11)°, Au-P 2.2859 (9) and Au-C 2.045 (4)A.

Synthesis and characterisation of mono- and di-nuclear mixed phosphathia complexes of gold(I): crystal structures of [Au(RSC2H4SR)]PF6, [Au(RSC3H6SR)]PF6and [Au2(RSC2H4SR)2]Cl2·4CH2Cl2(R = Ph2PC2H4)

Mononuclear gold(I) complexes of two linear P2S2 donor ligands, [AuL]PF6[L = RSC2H4SR or RSC3H6SR (R = Ph2PC2H4)] have been prepared by reaction of [AuCl(tht)](tht = tetrahydrothiophene) with L and TIPF6 in MeCN solution. The crystal structure of [Au(RSC2H4SR)]+ shows a primary P2-donor set with additional long-range thioether interactions giving a distorted linear geometry around AuI in the solid state; Au–P 2.284(7), 2.302(7), Au⋯S 2.899(6), 3.190(7)A. The structure of [Au(RSC3H6SR)]+ shows a very similar aggangement; Au–P 2.279(6), 2.287(6), A, Au⋯S 3.097(5), 3.101(6)A. The non-conducting binuclear species [Au2Cl2L] were obtained by reaction of [AuCl(tht)] with L in a 2 : 1 molar ratio in CH2Cl2 solution, while a 1 : 1 [AuCl(tht)]: RSC2H4SR ratio yielded the unusual species [Au2(RSC2H4SR)2]Cl2, the crystal structure of which shows a linear P2-donor set at each Au, giving a helical cavity which contains a Cl– anion. All complexes have been characterised by IR, 1H and 31P NMR spectroscopies, FAB mass spectrometry and microanalyses.

Preparation of supported gold catalysts from gold complexes and their catalytic activities for CO oxidation

A phosphine-stabilized mononuclear gold complex Au(PPh3)(NO3) (1) and a phosphine-stabilized gold cluster [Aug(PPh3)8](NO3)3 (2) were used as precursors for preparation of supported gold catalysts. Both complexes 1 and 2 supported on inorganic oxides such as α-Fe2O3, TiO2, and SiO2 were inactive for CO oxidation, whereas the 1 or 2/ oxides treated under air or CO or 5% h2/Ar atmosphere were found to be active for CO oxidation. The catalytic activity depended on not only the treatment conditions but also the kinds of the precursor and the supports used. The catalysts derived from 1 showed higher activity than those derived from 2. α-Fe2O3 and TiO2 were much more efficient supports than SiO2 for the gold particles which were characterized by XRD and EXAFS.

A novel mononuclear gold(I) complex: Synthesis and x‐ray structure of [Au{P(C6H5)3}3][SiF5] · 1.5 CH2Cl2

AbstractTris(triphenylphosphine)gold(I)‐pentafluorosilicate(IV) ([Au{P(C6H5)3}3][SiF5]) was prepared and the structure was determined by single crystal x‐ray diffraction. The complex crystallizes in the triclinic space group P1 (No. 2). The lattice constants are a = 14.634(2) Å, b = 17.180(2) Å, c = 22.212(3) Å, α = 86.48(1)°, β = 78.95(1)°, γ = 83.99(1)°. Number of molecules per cell: Z = 4. The gold atoms are coordinated to three triphenylphosphine ligands to form the trigonal planar cation [Au{P(C6H5)3}3]+. Separated from the cation is the [SiF5]− anion which is regular trigonal bipyramidal coordinated. No interactions between the fluorine atoms and the gold atoms were observed.

A mononuclear gold(I) complex containing a covalently bound ylide ligand. The structure of chloro[methyl(methylene)diphenylphosphoranyl-C]gold(I)

A mononuclear gold(I) complex containing a covalently bound ylide ligand. The structure of chloro[methyl(methylene)diphenylphosphoranyl-C]gold(I)

Structure of a mononuclear gold(I) complex containing a covalently bound ylide ligand

Etude du bromo [methyl(methylene) diphenylphosphoranyl-C] or (I); affinement jusqu'a R=0,0477

Neutral and Anionic Single-Bridged Binuclear Complexes of Gold(I) and Gold(III)

Abstract The reaction between mononuclear gold complexes, containing a poorly coordinating anionic (OClO3 −) or neutral (tetrahydrothiophen or dimethylsulphide) ligand, and pseudohalide gold complexes leads to binuclear neutral or anionic derivatives of the types (C6F5)AuXAuPPh3, (C6F5)AuXAu(C6F5)2PPh3, (C6F5)3 AuXAuPPh3, (C6F5)3AuXAu(C6F5)2PPh3 or Ph3BzP[(C6F5) AuXAu(C6F5)] (X being SCN or N3). The (2:l) reaction of Q[(C6F5)AuX] or Q[(C6F5)3AuX] with AgClO4 leads also to anionic binuclear complexes of the types Q[(C6F5)AuXAu(C6F5)] or Q(C6F5)AuXAu (C6F5)3] (Q being Ph3BzP or μ-nitrido-bis(triphenylphosphorus); X being SCN or N3).