Reactions Of Silver Research Articles

Infrared spectra and structures of the stable CuH(2)(-), AgH(2)(-), AuH(2)(-), and AuH(4)(-) anions and the AuH(2) molecule.

Gold is noble, but excited gold is reactive. Reactions of laser-ablated copper, silver, and gold with H(2) in excess argon, neon, and pure hydrogen during condensation at 3.5 K give the MH molecules and the (H(2))MH complexes as major products and the MH(2)(-) and AuH(4)(-) anions as minor products. These new molecular anions are identified from matrix infrared spectra with isotopic substitution (HD, D(2), and H(2) + D(2)) and comparison to frequencies calculated by density functional theory. The stable linear MH(2)(-) anions are unique in that their corresponding neutral MH(2) molecules are higher in energy than M + H(2) and thus unstable to M + H(2) decomposition. Infrared spectra are observed for the bending modes of AuH(2), AuHD, and AuD(2) in solid H(2), HD, and D(2), respectively. The observation of square-planar AuH(4)(-) attests the stability of the higher Au(III) oxidation state for gold. The synthesis of CuH(2)(-) in solid compounds has potential for use in hydrogen storage.

Matrix isolation infrared spectroscopic and density functional theoretical studies of the reactions of silver and gold atoms with carbon disulfide

The reactions of silver and gold atoms with carbon disulfide in solid argon have been investigated with infrared absorption spectroscopy. The ground state silver and gold atoms reacted with carbon disulfide to form the sulfur-bonded Ag-η1–SCS and Au-η1–SCS complexes spontaneously on annealing. The Ag-η1–SCS and Au-η1–SCS complexes underwent photochemical rearrangement to the inserted SAgCS and SAuCS molecules upon ultraviolet–visible irradiation. The product molecules were identified based on isotopic IR spectra and density functional theory calculations.

Chemical Equilibria Involving Reactions of Silver(I) Ions

Some overhead projector demonstrations on complex formation and solubility equilibria involving silver(I) ions are presented. The individual reactions can be arranged in such a way that after each addition silver(I) ions are shifted from one compound to a more stable compound.

Kinetic Study of the Reactions of Gas Phase Pd(aS0), Ag(5s 2S1/2), Au(6s 2S1/2), Cd(5s 1S0), and Hg(6s2 1S0) Atoms with Nitrous Oxide

The reactivity of gas-phase Pd(a1S0), Ag(5s 2S1/2), Au(6s 2S1/2), Cd(5s2 1S0), and Hg(6s2 1S0) with N2O as a function of temperature and pressure is reported. The transition metal atoms were produced by the photodissociation of an appropriate precursor molecule and detected by laser-induced fluorescence. The reaction of palladium with N2O is pressure dependent indicating adduct formation. The room-temperature limiting low-pressure third-order rate constant is (2.5 ± 0.8) × 10-30 molecule-2 cm6 s-1 in argon buffer. The limiting low-pressure third-order rate constant can be expressed as log k0(T) = −219.06 + 152(log T) − 30.5(log T)2 molecule-2 cm6 s-1 over the temperature range 294−523 K. The reactions of ground-state silver, gold, cadmium, and mercury with N2O are very slow, and only upper limits for the rate constants can be reported for these reactions.

Silver(I) and Silver(II) Complexes with Some Tetraazamacrocyclic Ligands in Aqueous Solutions

The reactions of silver(I) with isocyclam, scorpiand,trans-Me2[14]anN4, cis-Me6[14]anN4,(N-Me)Me2py[14]anN4 and py[12]anN4 were investigated.The stability constant of the Ag(I) complex with py[12]anN4 was determined. The aqueous solutions of the silver(II) complexes with the 14-membered ligands were obtained, and characterized by means of UV-VIS and CVA measurements. The Ag2+ ion does not form a five-coordinate complex with scorpiand. The formal potentials of the Ag(II)/Ag(I) system in the presence of scorpiand, trans-Me2[14]anN4, cis-Me6[14]anN4 and(N-Me)Me2py[14]anN4 were determined. The mechanism is also proposedfor the electroreduction of the silver(II) complexes with these compounds on a platinum electrode in aqueous solution.

Silver(I) complexes of triazine derivatives having stepped π–π interactions and 2D sheets

Reactions of silver(I) perchlorate and triflate with the triazine ligands 2,4,6-trimethoxy-1,3,5-triazine (L 1) and 2,4,6-triphenyl-1,3,5-triazine (L 2) have provided three novel silver complexes: [Ag(L 1) 2](ClO 4) ( 1), [Ag(L 1) 2](CF 3SO 3) ( 2) and [Ag 2(L 2)(CF 3SO 3) 2] ( 3). The crystal structures of these complexes have been determined by single-crystal X-ray diffraction. Each complex exhibits distinct coordination behavior and different frameworks. Complex 1 has a 1D stepped framework in which one crystallographically independent metal center interacts with two L 1 molecules and strong π–π interactions between the triazine planes of two L 1 molecules exist. On the other hand, complex 2 has a herringbone-like molecular packing in which the triflate ions are arranged between mononuclear complex cations. In complex 3, L 2 molecules are suspended between two double chains of silver triflate through the coordination to silver(I) ions to form the 2D sheet network structure. The factors that influence the crystal structure and packing are discussed.

Silver(I) Complex Assemblies with Nonplanar Aromatic Compounds

Reactions of silver(I) perchlorate with the nonplanar aromatic compounds triptycene (L1), 9,9-bifluorenylidene (L2), (R)-(+)-1,1‘-bi-2-naphthol (L3), and 2,5-norbornadiene (L4) have isolated four novel hydrocarbon-bridged polymeric complexes: [Ag3(L1)3(ClO4)3]·2C6H5Me (1), [Ag2(L2)2(ClO4)2]·C6H4Me2 (2), [Ag2(L3)(C6H6)2(ClO4)2] (3), and [Ag(L4)(ClO4)] (4). Structural studies using single-crystal X-ray diffraction have shown that all compounds contain extended two- or three-dimensional structures based on cation−π interactions. While complex 1 in the solid state contains a three-dimensional architecture in which the triangular molecule triptycene exhibits an unprecedented μ-η2-η2 or μ-η2-η2-η1 coordination mode depending on the steric requirements of the network, 3 represents the first example of π coordination of naphthol-containing micropores in its metal complexes. Infinite chains consisting of alternating silver ions and hydrocarbon molecules observed in both 2 and 4 are linked together by perchlorates...

Reactions of laser-ablated silver and gold atoms with dioxygen and density functional theory calculations of product molecules

The major new molecule observed here is gold dioxide. Extensive DFT calculations are compared for several silver and gold–dioxygen complexes.

Coordination of silver(I) at the surface of carbon paste electrodes modified with 2,5,8-trithia[9]-m-cyclophane as studied by cyclic voltammetry

The electrochemical behaviour of silver(I) at carbon paste electrodes (CPE) modified by 2,5,8-trithia[9]- m -cyclophane (TTCP) were studied voltammetrically in aqueous solutions of sodium perchlorate. Up to three cathodic peaks and anodic currents were observed in the cyclic voltammograms at the modified CPE, in contrast to the voltammograms of Ag + at the unmodified CPE in the presence and in the absence of TTCP in the solution. In the voltammograms high cathodic currents are contrasted by low anodic currents, e.g. in the case of 1×10 −5 M or 2×10 −5 M Ag + cathodic currents in are the range from 10 to 30 μA, whereas anodic currents are lower than 2 μA. The electrode reactions of silver at the modified electrode are discussed. The peak potential and peak currents of the cathodic currents depend strongly on the preceding cycle. The appearance of two cathodic peaks is attributed to oxidative formation of surface complexes of Ag(I) at positive potentials after preceding cathodisation with deposition of Ag(0). The reduction potential and consequently the stability of the complexes formed depended on the upper reversal potential. Furthermore, the influence of potentiostatic pretreatment and pretreatment at open circuit is studied. After pretreatment at open circuit a cathodic peak with time-dependent peak current appeared in the second scan to negative potentials.

Assembly of Metal Complexes

The reactions of silver(I) hexafuluorophosphate with imino nitroxyl diradicals yield complexes of [Ag2(pyrd-im2)2](PF6)2·2CH3OH (1) and [Ag2(bpy-im2)2](PF6)2·CH3OH (2) (pyrd-im2 = 3,6-bis(l'-oxyl-4′,4′,5′,5′-tetramethyl-4′,5′-dihydro-1′H-imidazol-2′-yl)pyridazine) and bpy-im2 = 2,2′-bis(1′-oxyl-4′,4′,5′,5′-tetramethyl-4′,5′-dihydro-1′H-imidazol-2′-yl)bipyridine)). Compelxes 1 and 2 have four radicals being double-helically assembled by the coordination to the silver ions. Magnetic susceptibility measurements revealed a strong antiferromagnetic interaction (-70.8(7) cm with H=2JS 1·S2) in 1 being operative through the pyridazine group, which was understood by the spin polarization mechanism. The reaction of MnSO4·4H2O with K2CrO4 in water yielded highly crystalline black 3. X-ray crystal-lographic study revealed that 3 has the chemical formula K[Mn2(μ-CrO4)2(μ-OH)2], which implies that the manganese ions are mixed valent Mn(II,III). Magnetic susceptibility measurement reveals that the antiferromagnetic interactions are operative without antiferromagnetic ordering and the exchange coupling constant was estimated to be −1.4 cm−1

Gold-Based Autometallography

Abstract Gold labels such as Nanogold® and colloidal gold are enlarged and visualized in the electron microscope or optically by the selective deposition of silver onto their surfaces. This process, known as autometallography (AMG), silver amplification or silver enhancement, is initiated by exposing the particles to a solution containing silver (I) ions and a reducing agent such as hydroquinone or npropyl gallate. Particles may be enlarged to between 30 and 100 nm in diameter, giving a distinctive black, punctate staining in the light microscope. Nanogold® labeling with silver amplification is one of the most sensitive methods available for histopathology applications such as in situ hybridization. With Catalyzed Reporter Deposition (CARD; also called Tyramide Signal Amplification, or TSA® ; NEN Life Sciences, Boston MA), it has been used to detect as few as 1-2 copies of viral DNA or RNA per cell. However, its uses are restricted by reactions of silver (I) with halides and other elements in tissues. Also, after signal development, self-nucleation and non-specific background deposition begin quickly, which can make end-point selection difficult or prevent incorporation into automated procedures.

Study of Reactions of Silver and Sulfur Clusters

The reactions between silver and sulfur clusters are studied with a laser double ablation reactor. The main reaction products are [AgS4]+, [AgS8]+, [AgS12]+, and [AgS16]+, which have different compositions from those of Ag/S clusters produced from Ag/S mixed sample by laser ablation. The photolysis of the products with a 193 nm excimer laser indicates that [AgS12]+ and [AgS16]+ have a photodissociation efficiency much higher than that of [AgS4]+ and [AgS8]+. The structure of the products and the mechanism of the reactions to form products [AgS12]+ and [AgS16]+ are discussed.

Stability constants of copper(I) and silver(I) complexes with open-chain, macrocyclic and -bicyclic aza-ligands in acetonitrile and comparison with results in dimethylsulfoxide

Stability constants of copper(I) and silver(I) with butylamines, monoaza- and diaza-crown ethers and cryptands have been determined in acetonitrile (AN). The stability constants of the silver(I) complexes are markedly larger than those with copper(I), and the complexation behaviour of silver(I) is determined to a much larger extent by the tendency to form inclusion complexes involving interactions with both, oxygen and nitrogen donor atoms. Silver(I) forms only 1:1 inclusion complexes with macrobicylic cryptand ligands, for example, whereas copper(I) additionally forms 2:1 (Cu +:ligand) complexes in which the cryptands act as monodentate ligands. A comparison of the results in AN with those reported in dimethylsulfoxide (N. Heidari, A. Thaler, H. Schneider, B.G. Cox, Inorg. Chim. Acta 279 (1998) 186) shows that in cryptand complexes the cation is normally well shielded from interactions with the solvent, such that the free energies of transfer of the ligands and cryptates are very similar. All other complexes show evidence of residual interactions of the complexed cations with the solvent. The observed difference between the complexation reactions of silver(I) and copper(I) in AN and in the responses of their complex stabilities to solvent transfer, can be attributed to different preferences of the two cations for binding with nitrogen and oxygen atoms; copper(I) in particular shows a very strong preference for nitrogen donor atoms.

Cathodic and Anodic Deposition of Mercury and Silver at Boron‐Doped Diamond Electrodes

The mechanisms of silver and mercury metal deposition on boron‐doped diamond electrodes were investigated using a prior model of three‐dimensional diffusion controlled nucleation/growth to interpret the data. The mechanism of nucleation depends upon the nucleation overpotential and metal ion concentration. At low overpotentials, instantaneous nucleation can be observed and, at high overpotentials or concentrations, the process becomes progressive. No underpotential phenomena are observed, consistent with exceptionally weak interaction between the deposited metal and the diamond surface. Active sites corresponding to a low density of surface sites on the electrode which act as critical nuclei during the electrodeposition. Anodic reactions of silver were also investigated. It was found that the resulting product depends on the silver concentration in the solution. Soluble Ag (II) forms only at low concentration . Increasing concentration leads to formation of sparingly soluble oxysalts of formula , where X is or , with voltammetric characteristics and adhesion similar to these found for cathodic metal deposits. © 1999 The Electrochemical Society. All rights reserved.

Kinetics of electrochemical processes in the system: silver/cyanide solutions

The kinetics and mechanism of electrode reactions of silver in cyanide solutions have been studied. The results of these studies have been compared with the data on cyanide ion adsorption on silver. The values of derivatives of the current with respect to the concentrations of cyanide ions and silver have been obtained both from the direct measurements and on the basis of model calculations taking account of the influence of cyanide and complex ion adsorption and the structure of electric double layers on the rate of electrochemical reaction. Candidates for the limiting stage have been considered.

Ag+ als Substituent eines Alkalimetalls in Ag2SrMnV2O8 / Ag+ As Substituent Of An Alkaline Metal In Ag2SrMnV2O8

Abstract Single crystals of Ag2 SrMnV2O8 have been prepared by reactions of metallic silver and a mixture of SrCO3, MnCO3 · H2O and V2O5. X-Ray investigations showed monoclinic symmetry, space group C6 2h -C2/c, a = 9.7022(9), b = 5.5882(5), c = 13.894(1), β = 90.41(1)°, Z = 4. The crystal structure is isotypic to Na2BaCuV2O8 and includes VO4 tetrahedra, MnO6 octahedra as well as irregular AgO8 and SrO10 polyhedra. Ag2SrMnV2O8 is characterized by a [MnV2O8] network incorporating Ag+ and Sr2+ or a [Ag2V28] frame incorporating Mn2+ and Sr2+ ions. Ag+ is able to replace an alkali ion in the cationic part of the crystal structure.

Zur Kristallchemie der Silber-Mangan-Oxovanadate Ag2BaMnV2O8 und (AgCa2)Mn2(VO4)3 / On the Crystal Chemistry of the Silver Manganese Oxovanadates Ag2BaMnV2O8 and (AgCa2)Mn2(VO4)3

Abstract Single crystals of Ag2BaMnV2O8 (I) and (AgCa2)Mn2(VO4)3 (II) have been prepared by reactions of metallic silver and mixtures of MnCO3H2O , V2O5 and L/II; BaCO3/CaCO3. Crystal structure investigations by X-ray methods led to I: trigonal symmetry, C1 3i-P3̅, a = 5.5693(4), c = 7.2706(6) A, Z = 1 and II: cubic symmetry, O10 h-Ia3̅d, a = 12.6084(9) Å, Z = 8 . Despite of different symmetry compound I is strongly related to the monoclinic compounds Ag2SrCuV2O8 and Na2BaCuV2O8, respectively. II belongs to the garnets. Compound I is characterized by [BaOg] nets with incorporated V5+ and Ag+ ions. The [BaOg] nets are connected by Mn2+ ions. A discussion of structural details of I with respect to Ag2SrMnV2O8, Na2BaCuV2O8 and the two modifications of K3Na(CrO4 )2 is given.

The development and functions of silver in water purification and disease control

The use of silver to control putrefaction of liquids and as a mitigate to the incursion and spread of disease can be traced to ancient times. In recent decades, studies have revealed the biochemical reactions of ionic silver that result in the inactivation of bacteria, fungi, protozoa, spirochetes, viruses, etc. not protected by proteinaceous membranes. The unique chemisorption of atomic oxygen on the surface of silver in both gaseous and aqueous media combined with freedom of movement of oxygen throughout the crystal lattice of the silver provides a reservoir of oxygen and thus sets silver apart in its catalytic activity. Studies have revealed that bulk silver in an oxygen-charged aqueous media will catalyze the complete destructive oxidation of microorganisms. However, the broad use of silver as a powerful clinical tool is still in the future because its full range of activity remains to be elucidated.

Coordination modes of the cyanoacetate ion; silver(I) and bis(η-cyclopentadineyl)tatinium(IV) cyanoacetates. X-ray crystal structures of [Ag(NCCH 2CO 2)] and [TiCp 2(NCCH 2CO 2) 2

Polymeric silver(I) cyanoacetate contains the classical bis(carboxylato- O, O′) bridged metal dimer arrays in which each pair of adjacent metal atoms is doubly bridged by co-planar carboxylate groups in the syn-syn conformation. These dimeric units are extended into a polymeric chain by terminal linkage of all cyano-nitrogen atoms to silver atoms of adjacent dimer units. In this manner, an individual cyanoacetate anion is O, O′, N-bonded to three different silver centres. EHMO calculations suggest weak direct metal-metal interactions can result from the mixing of metal s and p orbitals into the d 10 shells. Reactions of silver(I) or sodium cyanoacetates with [(η-C 5H 5) 2TiCl 2] afford the bis(cyanoacetato) complex [(η-C 5H 5) 2Ti(O 2CCH 2CN) 2] which has a solid state structure involving O-unidentate carboxylate groups, the cyano-nitrogen atoms not being bonded to a metal. This compound can also be prepared from [(η-C 5H 5) 2Ti(CH 3) 2] and cyanoacetic acid.

Structural studies of molecular-based nanoporous materials. Novel networks of silver(I) cations assembled with the polydentate N-donor bases hexamethylenetetramine and 1,3,5-triazine

Novel polymeric materials have been isolated from the reactions of silver(i) salts of poorly coordinating anions with the polydentate bases hexamethylenetetramine (hmt) and 1,3,5-triazine (trz), the one-dimensional polymer[Ag(hmt)] SbF 6 H 2 O 1, and the three-dimensional networked compounds [Ag 11 (hmt) 6 ][PF 6 ] 11 14H 2 O 2 and [Ag 6 (trz) 8 ][BF 4 ] 6 H 2 O 3, characterized by single-crystal X-ray analysis. Compound 1is monoclinic, space groupP2 1 /n, a=14.252(4), b=11.061(8), c=16.450(8) A, β=90.17(3)°. The structure contains a novel type of ribbon formed by hexagonal meshes of alternate Ag I ions and hmt molecules. The water molecules coordinated to the silver ions form hydrogen bonds which generate a three-dimensional network of unprecedented topology. Crystals of 2 are monoclinic, space group I2, a=19.552(6), b=10.856(6), c=25.749(11) A, β=92.83(3)°. It consists of an open three-dimensional network of complex topology with all the hmt molecules tetraconnected. Out of the eleven independent Ag I ions per formula unit, nine are biconnnected and two triconnected to the hmt bases. The large channels in the network contain many water molecules. Compound 3 is monoclinic, space group P2 1 /c, a=12.535(8), b=29.517(8), c=14.704(6) A, β=93.95(4)°. The structure contains six independent Ag ions and eight independent triazine molecules, which display varied connectivities to give a puzzling three-dimensional network.