Showing papers on "Oxidation state published in 1979"
TL;DR: In this article, the X-ray photoelectron spectra (X. p. s.) of Ti, V, Cr, Mn and Nb oxides with the metal ion in different oxidation states as well as of related series of mono-, sesqui- and di-oxides of the first row transi-tion metals have been investigated in detail.
Abstract: Systematics in the X-ray photoelectron spectra (X. p. e. s.) of Ti, V, Cr, Mn and Nb oxides with the metal ion in different oxidation states as well as of related series of mono-, sesqui- and di-oxides of the first row transition metals have been investigated in detail. Core level binding energies, spin-orbit splittings and exchange splittings are found to exhibit interesting variations with the oxidation state of the metal or the nuclear charge The 3d binding energies of the monoxides show a proportionality to Goodenough’s ( R — R c ). Other aspects of interest in the study are the satellite structure and final state effects in the X. p. e. s. of the oxides, and identification of different valence states in oxides of the general formulae M n O 2 n -1 and M 3 O 4 . The nature of changes in the 3d bands of oxides under-going metal-insulator transitions is also indicated.
138 citations
TL;DR: The conclusions are that the strength of this hydrogen bond in heme proteins is sensitive to both the oxidation state of the iron atom and to geometry changes on the order of those obtained from the x-ray coordinates.
Abstract: In all heme proteins for which crystal structures are available, the Ne of a histidyl residue is bonded to the heme iron and Nδ is hydrogen bonded to a carbonyl oxygen of the peptide backbone. We investigate here the possibility that a change in oxidation state of the iron or a change in the geometry of this hydrogen bond might change the hydrogen bond strength in a functionally significant way. Dimerization energies obtained from ab initio molecular orbital calculations on the hydrogen-bonded dimer of imidazole and planar formamide are used to represent the strength of this hydrogen bond in heme proteins. The effect of a change in iron oxidation state is modeled by varying the positive charge on imidazole. The effect of a change in hydrogen bond geometry is studied by employing x-ray coordinates for reduced and oxidized cytochrome c, deoxy- and metmyoglobin, and deoxy- and methemoglobin. Our conclusions are that the strength of this hydrogen bond in heme proteins is sensitive to both the oxidation state of the iron atom and to geometry changes on the order of those obtained from the x-ray coordinates. We speculate that the changes in oxidation state may be functionally coupled with changes in hydrogen bond geometry and that this hydrogen bond represents a feasible pathway to link protein conformation with redox potential or reactivity of the iron atom.
106 citations
102 citations
TL;DR: The method of direct electrochemical synthesis consists of oxidizing a metal anode in a non-aqueous solution containing a ligand (or ligand precursor) to produce the appropriate inorganic or organometallic compound as discussed by the authors.
Abstract: The method of direct electrochemical synthesis consists of oxidizing a metal anode in a non-aqueous solution containing a ligand (or ligand precursor) to produce the appropriate inorganic or organometallic compound. In many cases, the product precipitates directly in the cell, making for easy isolation, so that the technique is both direct and simple, and in addition the product yields are very high. One advantage of the technique is that the products are often derivatives of a low oxidation state of the metal; \examples of this include chromium(III) bromide, tin(II) and lead(II) diolates and thiolates, hexahalogenodigallate(II) anions, thorium diiodide, copper(I) thiolate complexes, and indium(I) derivatives of thiols, dithiols, and diols. In some systems, the low oxidation state compound undergoes subsequent reaction; for example, in the synthesis of RInX2 the reaction sequence involves the oxidation of indium metal to give InX, which then reacts with RX to give RInX2. Another possible post-electrolysis process is disproportionation. Examples of these various preparative routes will be discussed.
95 citations
TL;DR: In this paper, the results of a study of the interactions of Cl atoms and Cl2 with H2SO4 and H2O, the dominant components of stratospheric aerosols, at low temperature using X-ray photoelectron spectroscopy (XPS) were reported.
87 citations
TL;DR: In this article, the binding and activation of carbon monoxide, carbon dioxide, and nitric oxide by transition-metal complexes is discussed and the selected reactions of these molecules, which are catalyzed by metal complexes in solution.
Abstract: Publisher Summary This chapter discusses the binding and activation of carbon monoxide, carbon dioxide, and nitric oxide by transition-metal complexes and examines the selected reactions of these molecules, which are catalyzed by metal complexes in solution. These three simple oxides exhibit significantly different coordination chemistries and diverse reactivity patterns when bonded to transition-metal ions. The activation of each, thus poses different problems in the field of homogeneous catalysis. By considering these three simple inorganic oxides together, the chapter compares the similarities and differences apart from examining each independently. Homogeneously catalyzed reactions can be viewed as occurring in a sequence of steps, each of which involves a change in one or more of the following properties of the catalyst metal complex: coordination number, metal-ion oxidation state, and valence-electron count. Of these properties, the metal ion oxidation state seems most susceptible to confusion, especially with ligands, such as nitrosyl, π-bonded allyl, and bridging hydride.
86 citations
TL;DR: In this article, a series of platinum-tin catalysts with various platinum (0.35%) and tin contents have been effected at 450 °C and 23 °C using a microbalance.
76 citations
TL;DR: In this paper, the X-ray photoelectronic spectra of 2-mercaptobenzothiazole (LH) and its metal complexes have been measured and the coordination mode of the ligand and the oxidation state of the copper atom have been examined.
Abstract: The X-ray photoelectronic spectra of 2-mercaptobenzothiazole (LH) and its metal complexes have been measured. On the basis of the chemical shifts of the N(1s), S(2p), and Cu(2p3⁄2) electron binding energies, the coordination mode of the ligand and the oxidation state of the copper atom have been examined. It is suggested that, in HgL2, PbL2, AgL, and CuL3H2Cl complexes, the ligand is solely coordinated through the exocyclic sulfur atom, and that, in CuL, CuL2, PtL2, PdL2, NiL2, and CdL2 complexes, the ligand is coordinated through both the exocyclic sulfur and nitrogen atoms. In CuL2 and CuL3H2Cl, it was found that the copper was present in a (+1) oxidation state, and that part of the ligand molecules, bis(benzothiazol-2-yl) disulfide, resulted from oxidation of LH by the Cu2+ ion on complex formation.
58 citations
TL;DR: In this paper, the results of the present investigation indicate that the M(bqd)2I(0.50) materials, M = Ni, Pd, are best formulated as m(bqsd) 2I( 0.50), where S represents various amounts of the aromatic solvent employed for crystallization.
Abstract: : The results of the present investigation indicate that the M(bqd)2I(0.50) materials, M = Ni, Pd, are best formulated as M(bqd)2I(0.50).S materials where S represents various amounts of the aromatic solvent employed for crystallization. As deduced from resonance Raman, I-129 Mossbauer, and diffuse x-ray scattering measurements, the iodine is present as I3-, and thus the m(bqd)2I(0.50).S materials are indeed partially oxidized.
46 citations
TL;DR: The potential application of low-temperature radiolysis method to produce oneelectron-addition compounds of the oxygen-hemoprotein complexes in glassy matrices for spectroscopic analysis is demonstrated and the data show the differences in the pathway of oneElectron reduction of oxyperoxidase and oxymyoglobin, which can be correlated with basic functional properties of the hemoproteins.
41 citations
TL;DR: In this paper, the incorporation of Mo ions into a TiO 2 matrix has been studied as a function of preparation procedure and heat treatment conditions, using ESCA, UV and ESR spectroscopies.
TL;DR: Ahstraet-M6ssbauer spectra of 9 glauconite samples from Upper Cretaceous and Lower Tertiary strata in the South Island of New Zealand contain a broad shoulder due to low intensity absorption continuous between 1.0 and 2.5 mm/sec when the absorber is at room temperature as discussed by the authors.
Abstract: Ahstraet--M6ssbauer spectra of 9 glauconite samples from Upper Cretaceous and Lower Tertiary strata in the South Island of New Zealand contain a broad shoulder due to low intensity absorption continuous between 1.0 and 2.5 mm/sec when the absorber is at room temperature; the shoulder is absent, and sharp peaks are apparent in spectra taken with the absorber at 80~ The data suggest that electron transfer occurs between adjacent Fe 3+ and Fe z+ ions at room temperature. The low temperature spectra indicate that all Fe in the glauconites is in octahedral coordination. Fe z+ and Fe z+ ions occur in both cis and trans sites; Fe z+ shows a strong preference for cis sites whereas Fe 2+ shows an even stronger preference for trans sites. The partially variable oxidation state of Fe in glauconite is interpreted in terms of a geochemical model for glauconitization of a degraded or incomplete progenitor phyllosilicate. The model involves exchange of Fe ~+ for other cations which temporarily stabilize the progenitor, followed by FeZ§ 3+ charge transfer reactions. Each reaction results from the system's tendency towards equilibrium. The model is supported by the observation that artificially leached glauconite increases both its Fe z+ and its Fe z+ content when placed in a solution containing Fe 2+ as the only Fe ion present.
Patent•
10 Dec 1979TL;DR: In this article, the same inorganic metal/oxygen composition can be employed as a catalyst or as a combination catalyst/oxide gas carrier for the dehydrocoupling reaction when oxygen or an oxygencon- taining gas is heated with the toluene.
Abstract: Toluene dehydrocoupled products are produced by heating toluene in the vapor phase with an inorganic metal/oxygen composition which functions as an oxygen carrier and has an empirical formula selected from:
where M 1 is at least one element selected from silver, zinc, gallium, indium, thallium, germanium, phosphorus, arsenic, thorium, the lanthanides, Groups 1 a, 2a, 3b, 4b, and 8 of the Periodic Table of the Elements and mixtures thereof, and M 2 is an element selected from bismuth and antimony, and wherein a is 0.01 to 10, b is 0 to 10, and x is a number taken to satisfy the average valences of lead, M 1 and M 2 in the oxidation states in which they exist in the composition, with the proviso that when M 2 is bismuth, M 1 cannot be gallium or thallium; and when M 2 is antimony, M 1 cannot be indium, thallium, germanium, phosphorus, or thorium; and
where M 3 is at least one element selected from zinc, germanium, thorium, the lanthanides, Groups 1a, 3b, 4b, and 8 of the Periodic Table of the Elements and mixtures thereof, and M 4 is at least one element selected from indium, silver, Group 2a of the Periodic Table of the Elements, and mixtures thereof, and wherein a is 0.01 to 10, b is 0 to 10, and x is a number taken to satisfy the average valences of bismuth, M 3 , and M 4 in the oxidation state in which they exist in the composition to yield the toluene dehydrocoupled toluene product. Alternatively, the same inorganic metal/oxygen composition can be employed as a catalyst or as a combination catalyst/oxygen carrier for the dehydrocoupling reaction when oxygen or an oxygencon- taining gas is heated with the toluene.
TL;DR: The absorption spectrum and magnetic susceptibility vs temperature of β-alumina doped with Mn, Co, and Ni were measured in this paper, where the bands in the absorption spectrum for each metal were assigned and Dq, B, and C were calculated where possible.
Patent•
19 Jun 1979
TL;DR: Clean etchings at high rates are obtained using a solution containing sulfuric acid, hydrogen peroxide, a catalytic amount of a selenium compound of a +4 oxidation state and a secondary or tertiary alcohol as discussed by the authors.
Abstract: Clean etchings at high rates are obtained using a solution containing sulfuric acid, hydrogen peroxide, a catalytic amount of a selenium compound of a +4 oxidation state and a secondary or tertiary alcohol.
TL;DR: In this article, an active chromium trioxide is enriched in the solution by the application of an electrolytic current and the yield of intercalated substance is increased from 10% to more than 90%, referred to the added CrO3.
TL;DR: In this article, the tetrakis(trimethylphosphine oxide) copper(II) complexes located in the supercages of the Y zeolite lattice were investigated and it was suggested that this complex possesses pseudotetrahedral symmetry.
TL;DR: Mossbauer data has been obtained on six new, distinct tin intercalates which in addition to three others already reported in the literature comprise three distinct groups of compounds as discussed by the authors.
TL;DR: The microsymmetry of the cobalt complex species (Co2+ surrounded by oxygens) was found to change from octahedral, Oh, at low metal oxide concentrations to tetrahedral, Td, at high oxide concentrations as discussed by the authors.
TL;DR: The structure described by circular dichroism as unordered in metallothioneins was characterized using 270 MHz proton magnetic resonance spectroscopy and the oxidation-reduction properties of yeast Cu-thionein were studied by electron paramagnetic resonanceSpectroscopy.
Abstract: In an approach to elucidate the conformation of metallothioneins, far-ultraviolet circular dichroism was measured. Using 270 MHz proton magnetic resonance spectroscopy it was expected to characterize further the structure described by circular dichroism as unordered. In addition, the oxidation-reduction properties of yeast Cu-thionein were studied by electron paramagnetic resonance spectroscopy. The biological implications of the oxidation state of copper in Cu-thionein are discussed.
TL;DR: In this paper, the most probable ground-state electronic configuration of iridium has been suggested and the ligand field properties favorable to each oxidation state are discussed, and the presence of highly electron-attracting groups in the co-ordination sphere keeps Ir in the oxidation state III.
Abstract: Reactions of [IrH3(AsPh3)2(CNC6H4Me-p)] with chelating ligands yield substitution products having the metal in various oxidation states depending on the nature of the ligand Carboxylic acids, pentane-2,4-dione, and quadridentate Schiff bases give iridium(II) monomeric paramagnetic complexes; amino- and hydroxy-acids and o-amino- and o-hydroxy-phenols give paramagnetic iridium(IV) products The presence of highly electron-attracting groups in the co-ordination sphere keeps Ir in the oxidation state III All the complexes have been characterised by their vibrational, electronic, and magnetic properties, and in some cases the most probable ground-state electronic configuration of Ir has been suggested Ligand-field properties favourable to each oxidation state are discussed
TL;DR: It is suggested that the electrons of the metal-sulfur chromophore in blue copper proteins are delocalized and that an equilibrium: RS--Cu(II) in equilibrium or formed from RS.
TL;DR: In this paper, the stochastic properties of tetra-( p -sulfonatophenyl)-porphinatomanganese(II) and bisimidazole tetra( p -Sulfon atophenyl) porphinato-iron (II) complexes were studied in aqueous solutions at neutral pH.
01 Jan 1979
TL;DR: In this paper, the electron-attracting groups in the co-ordination sphere keep Ir in the oxidation state III, and the most probable ground-state electronic configuration of Ir has been suggested.
Abstract: Reactions of [IrH3(AsPh3)2(CNC6H4Me-p)] with chelating ligands yield substitution products having the metal in various oxidation states depending on the nature of the ligand. Carboxylic acids, pentane-2,4-dione, and quadridentate Schiff bases give iridium(II) monomeric paramagnetic complexes; amino- and hydroxy-acids and o-amino- and o-hydroxy-phenols give paramagnetic iridium(IV) products. The presence of highly electron-attracting groups in the co-ordination sphere keeps Ir in the oxidation state III. All the complexes have been characterised by their vibrational, electronic, and magnetic properties, and in some cases the most probable ground-state electronic configuration of Ir has been suggested. Ligand-field properties favourable to each oxidation state are discussed.