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Cyclic Trinuclear Gold(I) Compounds: Synthesis, Structures, and Supramolecular Acid- Base pi-Stacks
No full textMixed-Metal Triangular Trinuclear Complexes: Dimers of Gold-Silver Mixed-Metal Complexes from Gold(I) Carbeniates and Silver(I) 3,5-Diphenylpyrazolates.
No full textHeterobimetallic molecular species can produce unique optical, catalytic, and electronic properties. For example, gold-silver clusters have been synthesized and found to be highly efficient optical materials which possess enhanced Non-Linear Optical activity (NLO) over that of the pure silver and gold complexes. This paper describes a successful approach to the synthesis of organic solvent soluble mixed-metal gold-silver compounds with 2:1 and 1:2 Au:Ag ratios.
Trinuclear mixed-metal gold-silver compounds are obtained by the reaction of gold(I) carbeniate [Au(μ-C(OEt)=NC6H4-p-CH3)]3, TR(carb), with silver(I) pyrazolate [Ag(μ-3,5-Ph2pz)]3. The crystalline products are mixed-ligand, mixed-metal dimeric products [Au(carb)Ag2(μ-3,5-Ph2pz)2], [Au2(carb)2Ag(μ-3,5-Ph2pz)]•CH2Cl2. They have been characterized by elemental analysis and 1H NMR and mass spectrometry. The X-ray structure of [Au(carb)Ag2(μ-3,5-Ph2pz)2] shows it to be a dimer with two Ag•••Au contacts between the trinuclear units of 3.083(2) and 3.310(2) Å and with average intramolecular Ag•••Ag and Au•••Ag distances of ~ 3.3 and 3.2 Å, respectively. The structure of [Au2(carb)2Ag(μ-3,5-Ph2pz)]•CH2Cl2 is a dimer with one intermolecular Au•••Au attraction of 3.3354(10) Å and a short Ag•••Au distance of ~3.42 Å and intramolecular Ag•••Au and Au•••Au contacts of ~3.2 and ~ 3.3 Å, respectively. Packing diagrams of both complexes show that the dimeric units are independent, similar to their parent molecules. The white powders of these mixed-metal gold-silver compounds show a strong green luminescence under UV excitation at room temperature and a yellow luminescence at 77 K, a luminescence thermochromism
Mono and Tetranuclear Gold(I) Complexes of Tris(1-benzylimidazole-2-yl)-phosphine.
No full textThe reaction of tris(1-benzylimidazole-2-yl)phosphine, (Bzim)3P, 1, with Ph3AsAuCl in 1:1 stoichiometric ratio produced (Bzim)3PAuCl, 2. The reaction of (Bzim)3PAuCl with NaAuCl4 in 1:1 stoichiometry in dichloromethane gives an orange-yellow crystalline tetranuclear gold(I) cluster [{μ-N,N’-(Bzim)3PAuCl}2Au2][AuCl2][AuCl4], 3. Complex [{μ-N,N’-(Bzim)3PAuCl}2Au2][AuCl2]2, 4, is formed when the reaction stoichiometry of (Bzim)3PAuCl and NaAuCl4 is 2:1. The crystal structure of 3 shows the formation of a 12-membered macrocycle with Au•••Au distances of ∼3.0 A°. The structures of (Bzim)3PAuCl and 3 show Au•••H-C interactions ranging from 2.57 to 2.95A°.
The interest in tetranuclear gold clusters is due to their potential application as precursors for CO and olefin oxidation, their structural features and the presence of short Au•••Au interactions possibly influencing the optoelectronic properties observed in various polynuclear Au(I) compounds
Gold(I) and Silver(I) Mixed-Metal Trinuclear Complexes: Dimeric Products from the Reaction of Gold(I) Carbeniates or Benzylimidazolates with Silver(I) 3,5-Diphenylpyrazolate.
No full textTrinuclear mixed-metal gold-silver compounds are obtained by the reaction of gold(I) carbeniate [Au(μ-C(OEt)=NC6H4-p-CH3)]3, TR(carb), or gold(I) imidazolate [Au-μ-C,N-1-benzyl-2 imidazolate]3, TR(bzim), with silver(I) pyrazolate [Ag(μ-3,5-Ph2pz)]3. The crystalline products are mixed-ligand, mixed-metal dimeric products [Au(carb)Ag2(μ-3,5-Ph2pz)2], [Au2(carb)2Ag(μ-3,5-Ph2pz)]•CH2Cl2, [Au(bzim)2Ag2(μ-3,5-Ph2pz)], and [Au2(bzim)2Ag(μ-3,5-Ph2pz)]. They have been characterized by elemental analysis and 1H NMR and mass spectrometry. The X-ray structure of [Au-(carb)Ag2(μ-3,5-Ph2pz)2] shows it to be a dimer with two Ag•••Au contacts between the trinuclear units of 3.083(2) and 3.310(2) Å and with average intramolecular Ag•••Ag and Au•••Ag distances of ~3.3 and 3.2 Å, respectively.The structure of [Au2(carb)2Ag(μ-3,5-Ph2pz)]•CH2Cl2 is a dimer with one intermolecular Au•••Au attraction of 3.3354-(10) Å and a short Ag•••Au distance of ~3.42 Å and intramolecular Ag•••Au and Au•••Au contacts of ~3.2 and ~3.3 Å, respectively. Packing diagrams of both complexes show that the dimeric units are independent, similar to their parent molecules
Chemistry and Optoelectronic Properties of Stacked Supramolecular Entities of Trinuclear Gold(I) Complexes Sandwiching Small Organic Acids
No full textSelf-assembly of a High-Nuclearity Chloride-Centered Copper(II) Cluster. Structure and Magnetic Properties of [Au(PPh3)2][trans-Cu6(m-OH)6{m-(3,5-CF3)2pz}6Cl.
No full textA chloride-centered hexanuclear copper(II) pyrazolate [Au(PPh3)2]-[trans-Cu6(μ-OH)6{μ-(3,5-CF3)2pz}6Cl] is isolated from the reaction of the trinuclear copper(I) pyrazolate [Cu3{μ-(CF3)2pz}3] with PPh3AuCl and Ph3P in moist air. The six copper atoms are bridged by pyrazolate and hydroxyl ligands, above and below the copper plane. The chloride anion exists at the center of the planar cavity formed by the copper atoms with Cu-Cl distances of 3.02-3.13 Å. The magnetic susceptibility measurements show a strong antiferromagnetic coupling between the copper centers with an estimated exchange constant of J ~ 650 cm-1
Halide and Nitrite Recognizing Hexanuclear Metallacycle Copper(II) Pyrazolate.
No full textHalide-centered hexanuclear, anionic copper(II) pyrazolate complexes [trans-Cu6((3,5-CF3)2pz)6(OH)6X]-, X = Cl, Br, I are isolated in a good yield from the redox reaction of the trinuclear copper(I) pyrazolate complex [μ-Cu3((3,5-CF3)2pz)3] with a halide source such as PPh3AuCl or [Bu4N]X, X = Cl, Br, or I, in air. X-ray structures of the anioncentered hexanuclear complexes show that the six copper atoms are bridged by bis(3,5-trifluoromethyl)pyrazolate and hydroxyl ligands above and below the six copper atom plane. The anions are located at the center of the cavity and weakly bound to the six copper atoms in a μ6-arrangement, Cu-X =∼3.1A°. A nitrite-centered hexanuclear copper(II) pyrazolate complex [trans-Cu6((3,5-CF3)2pz)6(OH)6(NO2)]- was obtained when a solution of [PPN]NO2 in CH3CN was added dropwise to the trinuclear copper(I) pyrazolate complex [μ-Cu3((3,5-CF3)2pz)3] dissolved in CH3CN, in air. Blue crystals are produced by slow evaporation of the acetonitrile solvent. The X-ray structure of [PPN][trans-Cu6((3,5-CF3)2pz)6(OH)6(NO2)] complex shows the nitrite anion sits in the hexanuclear cavity and is perpendicular to the copper plane with a O-N-O angle of 118.3(7). The 19F and 1H NMR of the pyrazolate ring atoms are sensitive to the anion present in the ring. Anion exchange of the NO2- by Cl- can be observed easily by 1H NMR
Supramolecular Chain Assemblies Formed by Interaction of a p Molecular Acid Complex ofMercury with p-Base Trinuclear Gold Complexes
No full textLuminescent Chains Formed from Neutral, Triangular Gold Complexes Sandwiching TlI and AgI. Structures of {Ag([Au(m-C2,N3-bzim)]3)2}BF4 CH2Cl2, {Tl([Au(m-C2,N3-bzim)]3)2}PF6 0.5 THF (bzim ) 1-Benzylimidazolate), and {Tl([Au(m-C(OEt)dNC6H4CH3)]3)2}PF6 THF, with MAu6 (M ) Ag+, Tl+) Cluster Cores
No full textStructures and properties of gold(I) complexes of interest in biochemical applications.
No full textGold(I) compounds have several potential roles in biologically related chemistry. The relatively low toxicity
of gold and its lability allows human consumption of drugs formed with this element. Trinuclear
and tetranuclear clusters look particularly interesting because of the strong basicity of the gold(I) centers
in these molecules. Future studies are expected to lead to interesting new bio-related observations.
The ability of gold(I) compounds to interact with themselves aurophilically and with other heavy element
ions has produced spectroscopic properties which are sensitive to volatile organic compounds (VOCs) and
other molecular interactions. Thus bio-applicability for sensing toxic components appears reasonable
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