Showing papers on "Oxidation state published in 1997"
TL;DR: In this article, a comparison of the molecular structure and reactivity information of supported vanadium oxide catalysts is presented, which provides new fundamental insights into the catalytic properties of surface vanadia species during hydrocarbon oxidation reactions.
Abstract: Supported vanadium oxide catalysts, containing surface vanadia species on oxide supports, are extensively employed as catalysts for many hydrocarbon oxidation reactions. This paper discusses the current fundamental information available about the structure and reactivity of surface vanadia species on oxide supports: monolayer surface coverage, stability of the surface vanadia monolayer, oxidation state of the surface vanadia species, molecular structures of the surface vanadia species (as a function of environment and catalyst composition), acidity of the surface vanadia species and reactivity of the surface vanadia species. Comparison of the molecular structure and reactivity information provides new fundamental insights into the catalytic properties of surface vanadia species during hydrocarbon oxidation reactions: (1) the role of terminal VO, bridging VOV and bridging VO-support bonds, (2) the number of surface vanadia sites required, (3) the influence of metal oxide additives, (4) the influence of surface acidic and basic sites, (5) the influence of preparation methods and (6) the influence of the specific oxide support phase. The unique physical and chemical characteristics of supported vanadia catalysts, compared to other supported metal oxide catalysts, for hydrocarbon oxidation reactions are also discussed.
644 citations
TL;DR: In this article, the surface chemical composition, the crystalline structure, and the oxidation state of Co and Ni in the bulk as well as on the surface were characterized by X-ray diffraction (XRD), infrared spectroscopy (IRS).
Abstract: Films of general composition CoxNi1-xOy with x = 0, 11.1, 22.2, 33.3, 44.4, 55.6, 66.7, 77.8, 88.9, and 100 mol %, prepared by thermal decomposition of 2-propanol solutions of Ni and Co nitrates on Ni supports, have been characterized by X-ray diffraction (XRD), infrared spectroscopy (IRS), and X-ray photoelectron spectroscopy (XPS). These techniques have provided the surface chemical composition, the crystalline structure, and the oxidation state of Co and Ni in the bulk as well as on the surface. The results have revealed, in addition to previous work where NiO and NixCo2-xO4 solid solutions were found to be the predominant crystalline phases, that Ni and Co hydroxides interact in the surface layer of nanosized crystallites of the oxide phase. The interaction in the hydroxylated surface has a redox character and results in two oxidation states (+2 and +3) for both Ni and Co ions. This work has shown that Co hydroxide fragments are localized in the periphery of Ni hydroxide domains. The redox interaction...
303 citations
TL;DR: A tetranuclear ferric Keggin sandwich-type heteropolyanion has been synthesized by the reaction of the lacunary species Δ-Na8H[PW9O34] with FeCl2 followed by O2 oxidation in nonaqueous media.
Abstract: A tetranuclear ferric Keggin sandwich-type heteropolyanion has been synthesized by the reaction of the lacunary species Δ-Na8H[PW9O34] with FeCl2 followed by O2 oxidation in nonaqueous media. The structure of [(n-C4H9)4N]6[FeIII4(H2O)2(PW9O34)2]·4CH3CN·2CH2Cl2·2H2O (TBA-1) was determined by single-crystal X-ray diffraction (orthorhombic, Pbca; R = 0.0693 for 14 963 reflections with Fo > 4σ(Fo)). The compound was further characterized by infrared and UV−visible spectroscopy, electrochemistry, magnetic susceptibility, FAB mass spectrometry (FAB-MS), and elemental analyses. Five lines of evidence are consistent with the FeIII4 oxidation state: (i) valence sum calculations from the X-ray structure (ca. 2.86 ± 0.07 per Fe); (ii) the rest potential from cyclic voltammetry; (iii) charge balance requirements; (iv) titration with CeIV(SO4)2; and (v) oxidation by O2. In contrast to the tetranuclear ferric Wells−Dawson-derived sandwich complex, [FeIII4(H2O)2(P2W15O56)2]12-, TBA-1 can only be prepared from a ferrous...
151 citations
TL;DR: In this article, a combined electron spin resonance and diffuse reflectance spectroscopies were used to characterize the manganese oxides for the selective catalytic reduction of NO, and it was shown that this anchoring reaction proceeds at a Mn/OH = 1/2 ratio up to 4.5 wt % Mn loading, leading to a highly dispersed oxidic manganized layer.
Abstract: Alumina-supported manganese oxides, used as catalysts for the selective catalytic reduction of NO, were characterized by combined electron spin resonance and diffuse reflectance spectroscopies. Upon impregnation of the acetate precursor solution, the [Mn(H2O)6]2+ complex interacts strongly with surface hydroxyls of the γ-Al2O3. Evidence was obtained that this anchoring reaction proceeds at a Mn/OH = 1/2 ratio up to 4.5 wt % Mn loading, leading to a highly dispersed oxidic manganese layer. At higher loadings, the precursor complex is deposited on the surface concurrently. Upon drying at 383 K, part of the manganese is oxidized to higher oxidation states (Mn3+ and Mn4+), while a further increase in (average) oxidation state takes place upon calcination at 573 K. After calcination, the manganese species are present as a mixture of Mn2+, Mn3+, and Mn4+. At low loadings (<1 wt %), approximately equal amounts of these three oxidation states are present, whereas Mn3+ becomes the predominant species at higher loa...
133 citations
89 citations
TL;DR: In this paper, a XANES, EXAFS and visible-NIR study on the local copper environment in CuI-Y prepared by an original gas-phase reaction of H-Y with CuCl and in CuII-Y pre-processed by conventional ion exchange with an aqueous cupric salt is presented.
84 citations
TL;DR: In this paper, an extensive investigation on vanadium−dinitrogen complexes containing the [V(μ-N2)V]n+ skeleton with a variable oxidation state of the metal and reduction degree of dinitrogen, n varying from 6 → 5 → 4.
Abstract: This report details an extensive investigation on vanadium−dinitrogen complexes containing the [V(μ-N2)V]n+ skeleton with a variable oxidation state of the metal and reduction degree of dinitrogen, n varying from 6 → 5 → 4. This skeleton can be associated to alkali cations in ion-separated or ion-pair tight forms. The reaction of [(Mes)3V(thf)], 1 [Mes = 2,4,6-Me3C6H2], with Lewis acids [AlPh3, B(C6F5)3] removed the THF molecule leading under nitrogen to the formation of the diamagnetic complex [(Mes)3V(μ-N2)V(Mes)3], 4. The reaction of 1 with N2 also occurs under reducing conditions using Na or K metals. As supported by the electrochemical study, the preliminary stage is in both cases the formation of the vanadium(II) desolvated form [V(Mes)3]-, 5. The reaction of 5 with N2 in the case of potassium and in the presence of 1 leads to the compound {[(Mes)3V(μ-N2)V(Mes)3]-[K(digly)3]+}, 11, which, depending on the reaction conditions, undergoes a further reduction to [{K(digly)3(μ-Mes)2(Mes)V}2(μ-N2)], 12 [d...
74 citations
TL;DR: In this article, it is suggested that the reaction rates in propane and propene total oxidation can be influenced by the rate of oxidation of adsorbed======acetate and acrylate intermediates, respectively.
Abstract: Oxidation of the C
3
organic compounds propane, propene,
acrolein, propan-2-ol and acetone has been investigated over three
transition-metal oxide catalysts, Co
3
O
4
,
MgCr
2
O
4
and CuO, in a flow reactor and using
FTIR spectroscopy to study the adsorbed species.
Co
3
O
4
and MgCr
2
O
4
are very
active in propane and propene catalytic combustion. FTIR studies
suggest that adsorbed isopropoxide species and adsorbed acetone and
acetates are intermediates in propane oxidation while adsorbed
acrolein and acrylates are intermediates in propene oxidation. Flow
reactor studies support these hypotheses. It is suggested that the
reaction rates in propane and propene total oxidation can be
influenced, at low temperature, by the rate of oxidation of adsorbed
acetate and acrylate intermediates, respectively.
Co
3
O
4
and MgCr
2
O
4
are also
active and quite selective catalysts for the oxy-dehydrogenation of
propan-2-ol to acetone at low conversion, suggesting that the same
oxygen species are involved in total and partial oxidation of organic
compounds. CuO, as such, is not active in the adsorption and oxidation
of C
3
hydrocarbons and oxygenates, at low temperature. At
higher temperatures the reactants reduce the catalyst and catalytic
activity starts. The oxidation state of the CuO
x
catalyst can be evaluated by IR studying the transmittance of the
radiation upon different treatments.
71 citations
TL;DR: In this paper, the role of the surface oxides of a polycrystalline surface of a Pt polysilicon surface in the electrocatalytic oxidation of C1 to C4 primary alcohols has been investigated.
70 citations
TL;DR: In this paper, the synthesis and characterization of a redox-switchable hemilabile ligand (RHL), (η5-C5H5)Fe(η 5-C 5H4C6H4OCH2CH2PPh2) (1), are reported.
Abstract: The synthesis and characterization of a phosphinoalkylarene, redox-switchable hemilabile ligand (RHL), (η5-C5H5)Fe(η5-C5H4C6H4OCH2CH2PPh2) (1), are reported. This ligand, which incorporates a redox-active ferrocenyl group, exhibits oxidation-state-dependent bonding properties and, hence, affords electrochemical control over the electronic and steric environments of bound transition metal centers. Two equivalents of 1 complex to Rh(I) to yield a bis(phosphine), η6-arene complex [(η1:η6-(η5-C5H5)Fe(η5-C5H4C6H4OCH2CH2PPh2))(η1-(η5-C5H5)Fe(η5-C5H4C6H4OCH2CH2PPh2))Rh]+BF4- (2). Single-crystal X-ray diffraction studies of 2·1.25CH2Cl2, as well as solution spectroscopic data of 2, are consistent with this formulated piano-stool geometry. Foremost, the properties of 2 as a function of bound RHL state-of-charge are extensively investigated. Interestingly, 2D 1H NMR exchange spectroscopy (EXSY) studies demonstrate significantly faster intramolecular η6-arene, free arene exchange rates only upon oxidation of the lig...
70 citations
TL;DR: In this paper, the catalytic behavior of a chromium-doped alumina pillared clay (ACrPA) and a series of chromia-pillared clay materials (XSCr) for the deep oxidation of methylene chloride has been studied.
Abstract: The catalytic behavior of a chromium-doped alumina pillared clay (ACrPA) and a series of chromia-pillared clay materials (XSCr) for the deep oxidation of methylene chloride has been studied. Both types of catalysts showed a high activity (conversion > 80%) at T > 350°C. The ACrPA sample showed a virtually constant catalytic activity (conversion > 99%) in the 300–400°C temperature range while the activity of the XSCr samples markedly increased with the temperature reaching an almost total conversion at 400°C. XPS (X-ray photoelectron spectroscopy) and temperature programmed reduction (TPR) studies demonstrated that ACrPA is a Cr(VI) Cr(III) mixed valence catalyst, whereas XSCr samples contain only chromium(III) ion. The high activity shown by ACrPA at low temperatures was attributed to the presence of highly dispersed Cr(VI) species, which exhibited an unusually high stability. The metal oxidation state of the two chromium based systems seemed to be important in determining the catalytic activity. The increase of the activity with the Cr content in XSCr samples suggested that the acid sites in these catalysts were located on the chromia pillars.
TL;DR: An analysis of 250 MnOn fragments retrieved from the Cambridge Structural Database was used to derive a oxidation state independent R0 value of 1.754 A for Mn−O bonds that can be used to reproduce the oxidation state using the bond valence sum (BVS) method.
Abstract: An analysis of 250 MnOn fragments retrieved from the Cambridge Structural Database was used to derive the oxidation state independent R0 value of 1.754 A for Mn−O bonds that can be used to reproduce the oxidation state using the bond valence sum (BVS) method. The coordination numbers varied from 3 to 8 and the oxidation states from 2 through 7. Deviations of the BVS from an integer value are discussed. An analysis of the 1360 Mn−O bond distances used suggests that the BVS is more significant in discussing Mn−O structures than a comparison of bond distances.
TL;DR: In this paper, the authors used the characteristic line shapes of cerium to determine its oxidation state in alkali borosilicate glasses that are being developed for immobilization of plutonium, and they found that the redox state of Cerium doped to 7 wt% could be varied by a suitable choice of alkali elements in the glass formula.
TL;DR: In this paper, the role of the electrons and holes at the surface of semiconductor compounds in photocatalysis has been investigated in aqueous media for the reactions involving the series of compounds: nitrobenzene, nitrosobenzenes, n-nitrosophenol, phenylhydroxylamine, aniline, and p-benzoquinone.
Abstract: The role of the electrons and holes at the surface of semiconductor
oxides (TiO
2
and WO
3
) in heterogeneous
photocatalysis has been investigated in aqueous media for the
reactions involving the series: nitrobenzene, nitrosobenzene,
phenylhydroxylamine, aniline, and the related compound,
4-nitrosophenol. Qualitative and quantitative evaluation of most
intermediates and their time evolution suggest that the reductive
pathways are important and even predominant under a variety of
experimental conditions. This aspect is not only true at the beginning
of the process or for the readily reducible structures, but also
during the entire degradation process.
Each compound of the series is converted to all the others, even
though in widely different amounts. In the early part of the
photocatalytic process, with nitrosobenzene and with
phenylhydroxylamine, even in the presence of oxygen, the nitrogen
substituent undergoes simultaneous oxidation and reduction at
comparable rates, so that very little change in the mean oxidation
state of the system is observed. This suggests that photogenerated
electrons have a controlling role, particularly for some compounds in
the early steps of the photocatalytic transformation. For
4-nitrosophenol and p-benzoquinone, in the early steps of
degradation the reductive pathways represent the main route, even in
the presence of oxygen. As a consequence, for some compounds the
presence of an excess of oxygen in the reacting atmosphere decreases
the degradation rate, instead of promoting it, as is commonly observed
in photocatalysis. It is also remarkable that, for some compounds
examined, the redox reactions at the nitrogen-containing substituent
have a comparable or even more important role than the hydroxylation
of the aromatic ring, which was the predominant degradation pathway
for most of the other aromatic compounds.
TL;DR: In this paper, the surface chemistry of silicon nitride is strongly influenced by the processing environment, and the effect of mixing conditions on surface oxidation has also been analyzed on the green cast and pressed bodies prepared by dry and wet mixing using both water and alcohol as mixing vehicles.
Abstract: The surface chemistry of silicon nitride is strongly influenced by the processing environment. Mixing and forming steps can modify the oxidation state at the surface of the particle. The aim of the present investigation is to determine the possible changes and interactions on the surface of the particle induced during processing by different techniques of formation, such as isostatic pressing and slip casting. The effect of mixing conditions on surface oxidation have also been analysed on the green cast and pressed bodies prepared by dry and wet mixing using both water and alcohol as the mixing vehicles. X-ray photoelectron spectroscopy (XPS) has been used to characterize surface oxidation of the silicon nitride taking into account the Si2p, N1s and O1s binding energies, as well as the corresponding photoelectron line intensities. All processing treatments result in some surface oxidation. The Si2p peaks have two components in all studied conditions (due to nitride and oxynitride species) whereas N1s peaks are doublets for slip-cast samples and singlets in the pressed samples, thus suggesting a displacement of oxidized species by silica. In the case of slip-cast samples, the dispersant tetramethylammonium hydroxide (TMAH) seems to form a protective screen on the particles preventing further oxidation.
TL;DR: The oxidation of 2-aminothiazole by W191G represents an example of how the oxidative capacity inherent in the heme prosthetic group and the specific binding behavior of artificial protein cavities can be harnessed and redirected toward the oxidation of organic substrates.
Abstract: The binding and oxidation of an artificial substrate, 2-aminothiazole, by an engineered cavity of cytochrome c peroxidase is described. The W191G mutant has been shown to create a buried cavity into which a number of small heterocyclic compounds will bind [Fitzgerald, M. M., Churchill, M. J., McRee, D. E., & Goodin, D. B. (1994) Biochemistry 33, 3807-3818], providing a specific site near the heme from which substrates might be oxidized. In this study, we show by titration calorimetry that 2-aminothiazole binds to W191G with a Kd of 0.028 mM at pH 6. A crystal structure at 2.3 A resolution of W191G in the presence of 2-aminothiazole reveals the occupation of this compound in the cavity, and indicates that it is in van der Waals contact with the heme. The WT enzyme reacts with H2O2 to form Compound ES, in which both the iron center and the Trp-191 side chain are reversibly oxidized. For the W191F (and perhaps the W191G) mutants, the iron is still oxidized, but the second equivalent exists transiently as a radical on the porphyrin before migrating to an alternate protein radical site [Erman, J. E., Vitello, L. B., Mauro, J. M., & Kraut, J. (1989) Biochemistry 28, 7992-7995]. Two separate reactions are observed between 2-aminothiazole and the oxidized centers of W191G. In the one reaction, optical and EPR spectra of the heme are used to show that 2-aminothiazole acts as an electron donor to the ferryl (Fe4+dO) center of W191G to reduce it to the ferric oxidation state. This reaction occurs from within the cavity, as it is not observed for variants that lack this artificial binding site. A second reaction between 2-aminothiazole and peroxide-oxidized W191G, which is much less efficient, results in the specific covalent modification of Tyr-236. Electrospray mass spectra of the W191G after incubation in 2-aminothiazole and H2O2 show a modification of the protein indicative of covalent binding of 2-aminothiazole. The site of modification was determined to be Tyr-236 by CNBr peptide mapping and automated peptide sequencing. The covalent modification is only observed for W191G and W191F which form the alternate radical center. This observation provides an unanticipated assignment of this free radical species to Tyr-236, which is consistent with previous proposals that it is a tyrosine. The oxidation of 2-aminothiazole by W191G represents an example of how the oxidative capacity inherent in the heme prosthetic group and the specific binding behavior of artificial protein cavities can be harnessed and redirected toward the oxidation of organic substrates.
TL;DR: In this article, a new expression was devised empirically to accommodate zero and some negative oxidation states in the bond-valence sum approach for homoleptic copper and nickel complexes of various coordinating atoms in several oxidation states.
Abstract: A new expression is devised empirically to accommodate zero and some negative oxidation states in the bond-valence sum approach. The method is worked out in detail for a number of homoleptic copper and nickel complexes of various coordinating atoms in several oxidation states of the metals. An implication of the expression is a linear variation between 1/req and 1/rax in octahedral MX6 moieties, where req and rax are, respectively, the average equatorial and axial bond lengths. This is verified in Cu2+X6 chromophores for X = F, O, N and S. The usefulness of the new expression in assessing the compatibility of a coordination sphere with an oxidation state of a metal ion is demonstrated by exemplary applications to some inorganic complexes, azurin and urease.
TL;DR: In this article, an ab initio cluster approach was used to evaluate the thermodynamics and reaction mechanisms of the adsorption and reduction of gold on galena surfaces, and the reaction energies were calculated for the adaption of AuCl4− from solution and for the stepwise reduction from Au(III) to Au(0) by using an ABINI cluster approach.
Patent•
01 Aug 1997
TL;DR: In this article, a method of dissolving in an ionic liquid a metal in an initial oxidation state below its maximum oxidation state, characterised in that the Ionic liquid reacts with the metal and oxidises it to a higher oxidation state.
Abstract: A method of dissolving in an ionic liquid a metal in an initial oxidation state below its maximum oxidation state, characterised in that the ionic liquid reacts with the metal and oxidises it to a higher oxidation state. The initial metal may be in the form of a compound thereof and may be irradiated nuclear fuel comprising UO2 and/or PuO2 as well as fission products. The ionic liquid typically is nitrate-based, for example a pyridinium or substituted imidazolium nitrate, and contains a Bronstead or Franklin acid to increase the oxidising power of the nitrate. Suitable acids are HNO3, H2SO4 and [NO+]. Imidazolium nitrates and certain pyridinium nitrates form one aspect of the invention.
TL;DR: The reaction of [2-PyLi] with [Cp2Pb] produces [Pb(2-py)3Li·THF] (1), containing the first example of a low oxidation state group 14 tris(pyridyl) ligand as mentioned in this paper.
TL;DR: In this article, a series of new "magic number" metal oxide clusters are described for the group V metals antimony and bismuth, and localized covalent bonding schemes are suggested for these clusters, and polyhedral cage structures are proposed.
Abstract: A series of new “magic number” metal oxide clusters are described for the group V metals antimony and bismuth. Specific nonstatistical stoichiometries of MxOy cation and anion clusters are formed preferentially in the gas phase when oxidized metal is vaporized or when metal is vaporized and combined with gas phase oxygen (e.g., Bi7O10+, Bi9O14+). Essentially the same stoichiometries are seen for antimony and bismuth analogues. The species produced in cluster growth are also produced preferentially by photodissociation of larger clusters. Localized covalent bonding schemes are suggested for these clusters, and polyhedral cage structures are proposed. The stoichiometries observed require a 3+ metal oxidation state in the small clusters, which shifts over to one or more 5+ metal atoms in larger clusters.
TL;DR: The reaction of ammonium and iminium tetraphenylborate salts with transition-metal systems in a low oxidation state has been investigated in this article, where the NH bond activation was shown to be very selective.
TL;DR: In this article, the surface and bulk characteristics of U oxides were investigated by x-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), which indicated that the U cations in U3O8 are composed of +5/+6 (2/1) or +4/+6 ǫ(1/2) oxidation states.
Abstract: The reactions of acetone were investigated on α U3O8 (stoichiometric and H2 reduced) by temperature programmed desorption. The surface and bulk characteristics of U oxides were investigated by x-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD). The comparison between the XPS U 4f7/2 binding energy of β UO3, α U3O8, and UO2 indicated that the U cations in U3O8 are composed of +5/+6 (2/1) or +4/+6 (1/2) oxidation states. XPS of H2 reduced α U3O8 (at 800 K) indicated a shift of the U 4f7/2 binding energy from 381.6 (unreduced) to 380.5 eV (reduced) as well as the appearance of two satellites at 387.0 and 397.4 eV. These new XPS lines’ positions are characteristic of U+4 cations of UO2. Similar results were observed upon Ar-ion sputtering of α U3O8. Ar-ion sputtering of β UO3 also results in the reduction of U+6 cations to U+4 cations. XRD of H2 reduced α U3O8 indicated that all of the α U3O8 phase was transformed to the UO2 phase. A considerable difference between the reactivity of the surfaces of U3O8 and UO2 towards acetone was observed. A carbon–carbon bond formation reaction giving isobutene was observed only on the α U3O8 surface indicating its structure-sensitive nature and/or its sensitivity towards changing the oxidation state of U cations. This reaction has not been observed on the surfaces of actinide oxides before. On the other hand, acetone reacted on UO2 to give mainly propene. This latter reaction (which is a C–O bond dissociation) is most likely due to the capacity of UO2 to accommodate large numbers of atomic oxygen in interstitial positions while maintaining its structure intact.
TL;DR: X-ray photoelectron spectroscopy was applied for Ziegler-Natta catalysts and the oxidation state of titanium chloride was studied from the analysis of the Ti 2 p 3 2 peak.
Abstract: X-ray photoelectron spectroscopy was applied for Ziegler-Natta catalysts and the oxidation state of titanium chloride was studied from the analysis of the Ti 2 p 3 2 peak. It was observed that the state of titanium chloride on the catalysts was changed by the reaction with the co-catalyst.
TL;DR: Experimental and calculated cluster geometries agree satisfactorily, and the formal oxidation states of the gold atoms could be confirmed, but for the In centers no interpretable differences of the Mulliken charges were found.
Abstract: The insertion of InBr into the Au−Br bond of [(Ph3P)AuBr] in tetrahydrofuran (thf) in the presence of [(CH2PPh2)2] (dppe) leads to the formation of an orange complex [(dppe)2Au]+[(dppe)2Au3In3Br7(thf)]-, 2. Analytical, spectroscopic, and X-ray structural investigations showed that this product is an anionic analogue of a neutral chloride complex [(dppe)2Au3In3Cl6(thf)3], 1, prepared recently. Both complexes have an Au3In3 cluster core of approximate C2v symmetry with one extremely short Au−Au bond [Au1−Au3 2.575(1) A] as part of a quasi-linear array P1−Au1−Au3−P4, suggesting the presence of a bis(phosphine) complex of the neutral Au2 molecule as part of the cluster. The third gold atom (Au2) is then assigned oxidation state +1. To gain deeper insight into the structure and bonding of this novel class of gold cluster compounds, regarding mainly the peculiar cluster geometry, the charge distribution, and the oxidation states, a series of scalar relativistic all-electron density functional (DF) calculations ...
TL;DR: In this paper, the synthesis of mineral phases of iron formed under hydrolytic conditions have been studied using ambient and hydrothermal methods in the presence and absence of the oxalate (ox) template.
Abstract: The syntheses of mineral phases of iron formed under hydrolytic conditions have been studied using ambient and hydrothermal methods in the presence and absence of the oxalate (ox) template. A systematic survey of experimental parameters revealed how the oxolate template can influence crystal morphology, iron oxidation state and the nature of the phase formed. In addition to observing biomimetic control over crystal morphology of magnetite, two iron(II) hydrolytic oxalate phases were observed, humboldtine, FeII(ox)(H2O)2, and the new phase, FeII2(ox)(OH)2, which was identified by single-crystal X-ray diffraction.
TL;DR: The adsorption of C60 in sub-monolayer and monolayer coverages on Cs-precovered Au(110) has been investigated by photoemission and high-resolution electron-energy-loss spectroscopy as mentioned in this paper.
Abstract: The adsorption of C60 in submonolayer and monolayer coverages on Cs-precovered Au(110) has been investigated by photoemission and high-resolution electron-energy-loss spectroscopy Complete fullerene monolayers display discrete molecular oxidation states of approximately -3, -4, and -6 in the presence of Cs The oxidation states were determined by a comparison of monolayer electronic structure and vibrational mode frequencies with those of the bulk fullerides There is no evidence for oxidation states of -2 and -5 Surface-specific measurements on bulk vacuum distilled alkali-fulleride samples showed a strong similarity between the properties of the single-layer films and the surface layers of the bulk material Annealing experiments demonstrated that it was possible to produce a well-ordered, close-packed monolayer of C60 with an oxidation state of -3, which may be a useful precursor in producing a metastable fcc Cs3C60 film by epitaxial growth Bonding with the substrate stabilized this film with respect to bulk samples leading to desorption only at temperatures >900 K Electron-energy-loss spectroscopy of submonolayer C60 in the presence of multilayers of Cs indicates that filling of the lowest unoccupied molecular orbital (LUMO)+1 states occurs Completion of the monolayer results in extra charge occupying the LUMO band only However, LUMO+1 occupation can also be brought about by sandwiching complete fullerene monolayers between Cs layers
Patent•
16 Dec 1997TL;DR: In this paper, a process for oxidizing volatile organic compounds to carbon dioxide and water with the minimal addition of energy is described, where a mixture of the volatile organic compound and an oxidizing agent is exposed to a catalyst which includes a noble metal dispersed on a metal oxide which possesses more than one oxidation state.
Abstract: Disclosed is a process for oxidizing volatile organic compounds to carbon dioxide and water with the minimal addition of energy. A mixture of the volatile organic compound and an oxidizing agent (e.g. ambient air containing the volatile organic compound) is exposed to a catalyst which includes a noble metal dispersed on a metal oxide which possesses more than one oxidation state. Especially good results are obtained when the noble metal is platinum, and the metal oxide which possesses more than one oxidation state is tin oxide. A promoter (i.e., a small amount of an oxide of a transition series metal) may be used in association with the tin oxide to provide very beneficial results.
TL;DR: The heterometallic complexes (C5Me5)W(O)2Ru4(CO)10(μ4-PPh)(CCPh) as discussed by the authors, which contain examples of oxo-bridged tungsten−ruthenium bonds, have been prepared by condensation of Ru4(C7H8)13(μ3PPh) and Ru5(C6H8).