Insertion Of Transition Metals Research Articles

Synthesis of Green Brucite [NixMg1−x(OH)2] by Incorporation of Nickel Ions in the Periclase Phase (MgO) Applied as Pigments

Magnesium oxide is typically white and can be colorized with transition metal insertion by doping. We present the preparation of a green-colored hydroxide by the exchange of Mg2+ on the crystalline lattice with Ni2+ in MgO, using three nickel salts. MgOst was prepared by the colloidal starch suspension method, using cassava starch. The oxides and hydroxides, before and after, were characterized by X-ray diffraction (XRD), and show that a phase change occurs: a transition from periclase (MgO) to brucite (Mg(OH)2) due to the incorporation of nickel ions from different salts (acetate, chloride, and nitrate), resulting in the solid solution [NixMg1−x(OH)2]. The FTIR spectrum corroborates the crystallographic structure identified through XRD patterns, confirming the formation of a crystal structure resembling brucite. The new samples present a green color, indicative of the incorporation of the Ni2+ ions. The antimicrobial activity of products resulting from the doping of magnesium oxide with nickel and the precursor MgOst was assessed through the minimum inhibitory concentration (MIC) test. The evaluation included three bacterial strains: Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Salmonella gallinarum (ATCC 9184), and a yeast strain, Candida albicans (ATCC 10231). The obtained results were promising; the tested samples exhibited antimicrobial activity, with a MIC ranging from 0.312 to 0.625 μg.μL−1. The nickel compound, derived from the precursor chloride salt, demonstrated superior MIC activity. Notably, all tested samples displayed bactericidal activity against the S. aureus strain and exhibited a broad spectrum of inhibition, encompassing both Gram-positive and Gram-negative strains. Only the nickel compounds derived from precursors with acetate and nitrate anions demonstrated antimicrobial activity against C. albicans, exhibiting a fungistatic behavior. Based on the conducted studies, [NixMg1−x(OH)2] has emerged as a promising antimicrobial agent, suitable for applications requiring the delay or inhibition of bacterial growth.

Effects of transition metal doping on CsGeBr3 perovskite: First-principles study

Metal halide perovskites have shown the most promising results as the light-harvesting section of photovoltaics and opto-electronic devices. Among the non-toxic halide perovskites, CsGeBr3 was found to be the best candidate for opto-electronic applications; however, it is understood that the efficiency of CsGeBr3 can be further increased with the insertion of transition metals as dopants. In this article, the first-principles density functional theory calculations are used to predict the mechanical, structural, electronic, and optical properties of pristine, Ni-doped, Mn-doped, and Fe-doped CsGeBr3 with 12.5% of doping concentration. All the doped materials are found to be ferromagnetic and mechanically stable. They have finite magnetization values. The optical absorption edge in all the doped materials shows that they have additional peaks within the large emission range of solar radiation, which makes them more suitable than the pristine material for photovoltaics and opto-electronic applications. Among the doped materials, Mn-doped and Fe-doped CsGeBr3 have comparably higher absorption peaks and are almost identical in shape. The electronic bandgap is smaller than the pristine structure in the case of Fe-doped CsGeBr3 and larger for Ni and Mn-doped CsGeBr3. These combinational analyses lead to the decision that, among the non-toxic, inorganic perovskite materials, Fe-doped CsGeBr3 is better suited for the use in opto-electronic applications.

Bifunctional P-Intercalated and Doped Metallic (1T)-Copper Molybdenum Sulfide Ultrathin 2D-Nanosheets with Enlarged Interlayers for Efficient Overall Water Splitting.

Metallic (1T) molybdenum disulfide (MoS2) is a much better electrocatalyst than the semiconducting (2H) MoS2 because of its superior conductivity, presence of active basal planes, and bulky interlayers. However, the lack of thermodynamic stability has hindered its practical uses. The insertion of transition metals and nonmetals in the interlayers and the crystal is known to improve both the thermodynamic stability and the catalytic efficacy of 1T-MoS2. In this study, for the first time we have developed an electrocatalyst for water splitting based on metallic copper molybdenum sulfide (1T-CMS). The present catalyst, P-doped and intercalated 1T-CMS ultrathin 2D nanosheets on carbon cloth (P-1T-CMS@CC), demonstrates excellent catalytic efficacy for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). It required an overpotential of 95 mV for HER and of 284 mV for OER at a current density of 10 mA cm-2. The P-1T-CMS@CC(+ -) device also shows excellent performance, requiring a cell voltage of only 1.51 V at a current density of 10 mA cm-2.

Diphosphoniodiphosphene Formation by Transition Metal Insertion into a Triphosphenium Zwitterion.

Treatment of two equivalents of the triphosphenium zwitterion L with sources of Ni0 and Pd0 form the mononuclear η2 -diphosphoniodiphosphene complexes 1 and 2. The reaction between L and [FeCp(CO)2 ]2 results in the binuclear μ-η1 :η1 -diphosphoniodiphosphene iron complex 3, which features an alternative bonding motif of the diphosphoniodiphosphene unit. The formation of these species has been confirmed by spectroscopic methods and single-crystal X-ray diffraction analysis, and their electronic structures have been elucidated using computational methods.

Composition of Kaew Angwa by X-Ray Fluorescence Spectroscopy (XRF)

The ancient glass, “Kaew Angwa” is a kind of materials used in decorative art work with colored glass casted on metal. The common Kaew ANgwa can be found in green, blue, colorless and yellow. Brown and red Kaew Angwa are rather scarce. Thin sheet of colored glass is tightly bonded to the metal which cracks when it is bent but still stays intact. Kaew Angwa can reflect lights to the colors of the colored glasses beautifully. Kaew Angwa can be cut with scissors which make it’s easiness for ornament.In this presentation, composition of Kaew Angwa will be examined by X-Ray Fluorescence Spectroscopy (XRF). The colored glass will be identified and shown that the insertion of transition metals (iron, manganese, and copper) into the crystal structure of silica causes Kaew Angwa to be colored.There is no known method to fabricate Kaew Angwa to be exactly like the ancient one. The results from this work will give the general idea on the composition of colored glasses. Several trials have been performed on how to bond colored glass and metal, for example silver mirroring on cover glass and sealed with epoxy for protection. Further experiments will be performed on thin colored glass

Improvement in hydrogen desorption from β- and γ-MgH2 upon transition-metal doping.

A thorough study of the structural, electronic, and hydrogen-desorption properties of β- and γ-MgH2 phases substituted by selected transition metals (TMs) is performed through first-principles calculations based on density functional theory (DFT). The TMs considered herein include Sc, V, Fe, Co, Ni, Cu, Y, Zr, and Nb, which substitute for Mg at a doping concentration of 3.125 % in both the hydrides. This insertion of TMs causes a variation in the cell volumes of β- and γ-MgH2 . The majority of the TM dopants decrease the lattice constants, with Ni resulting in the largest reduction. From the formation-energy calculations, it is predicted that except for Cu and Ni, the mixing of all the selected TM dopants with the MgH2 phases is exothermic. The selected TMs also influence the stability of both β- and γ-MgH2 and cause destabilization by weakening the MgH bonds. Our results show that doping with certain TMs can facilitate desorption of hydrogen from β- and γ-MgH2 at much lower temperatures than from their pure forms. The hydrogen adsorption strengths are also studied by density-of-states analysis.

ChemInform Abstract: Transition‐Metal Mediated Carbon—Sulfur Bond Activation and Transformations

AbstractReview: 207 refs.

Transition-metal mediated carbon–sulfur bond activation and transformations

C-S bond activation, cleavage and transformations by means of transition metal compounds have recently become more and more important in the petroleum industry and synthetic chemistry. Homogeneous transition metal compounds have been investigated in order to provide the fundamental insight into the C-S bond cleavage in problematic organosulfur compounds such as thiophene, benzo- and dibenzothiophene derivatives. Rendering transition-metal mediated reactions with organosulfur compounds catalytic may provide promising routes to deep hydrodesulfurization of petroleum feedstocks, and offer potentially useful synthetic protocols for cross-couplings and biomimetic organic synthesis. During the last few decades increasing work was documented on C-S bond activation and transformations by means of transition metal compounds. This review summarizes the recent advances in C-S bond cleavage via the insertion of transition metals into the inert C-S bonds of these problematic organosulfur compounds, and transition-metal mediated C-S bond transformations via C-S activation through cross-couplings of thioesters, ketene dithioacetals, sulfonyl chlorides, and other diverse organosulfur compounds.

Exhaust gas recirculation for on-board hydrogen production by isooctane reforming: Comparison of performances of metal/ceria–zirconia based catalysts prepared through pseudo sol–gel or impregnation methods

Isooctane reforming under conditions which are set by exhaust gas can be used to generate hydrogen on-board. Isooctane reforming reactivity tests have been performed with bimetallic catalysts Co-noble metal/ceria–zirconia, prepared either by insertion of transition metal in a ceria–zirconia matrix, either by their impregnation on ceria–zirconia. The influence of the preparation procedure on the activity of the noble metal-doped catalysts is discussed.

Electrochemical and theoretical investigation on the reaction of transition metals with Li 3N

The electrochemical reactivity of Li 3N with transition metals (M = Mn, Fe, Co, Ni) is examined by discharge/charge, cyclic voltammetry, X-ray diffraction and X-ray photoelectron spectroscopy measurements. An attempt is made to understand this reversible electrochemical reaction of transition metals with Li 3N from the chemical reactions point of view. Density functional theoretical calculation results suggest that a stable complex MNLi 3 could be formed by the insertion of transition metal in Li 3N with exothermic as an intermediate, subsequent the decomposition process of these insertion compounds should make a main contribution to release Li.

Electrochemical and quantum chemical studies of the reactions of transition metals M (M = Co, Fe and Ni) with LiF and Li 2O

It has been a puzzle that transition metals can unexpectedly react with lithium-based matrixes of LiF and Li 2O in the potential versus Li/Li + range from 0.01 to 3.5 V at room temperature. The electrochemical and theoretical investigations on the reactions of transition metals M (M = Co, Fe and Ni) with LiF and Li 2O were carried out. The electrochemical reactivity of metal cobalt with LiF and Li 2O has been examined by the discharge and charge, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements. Density functional theoretical calculation results suggested that the stable compounds MLiF and MLi 2O could be formed by the insertion of transition metal (M) in lithium-based matrixes with exothermic as an intermediate. The theoretical calculations provide an understanding in chemical reaction of M with LiF and Li 2O. The small molecular or clusters reaction may play an important role in the electrochemical reaction of metal with transition Li 2O or LiF, which could be used to explain for the unexpectedly reaction of transition metal with LiF and Li 2O.

Selectivity of gas phase adsorption of propene and propane onto mesoporous silica materials derivatised with Ag(I) and Cu(II) at low surface coverages: comparison between equilibrium adsorption and flow microcalorimetry studies

Adsorption selectivity for propene over propane of mesoporous aluminosilicate monoliths derivatised with Ag(I) and Cu(II) has been studied from the gas phase at low surface coverages at 298 K. The insertion of transition metals was achieved by ion exchange, incipient wetness impregnation or direct incorporation during the synthesis stage. The overall transition metal content in the samples ranged between 2 and 20 wt.%. Two-cycle adsorption of each gas measured at pressures up to 300 mbar was used to determine the reversible and irreversible contributions to the amount adsorbed under equilibrium conditions. Flow microcalorimetry measurements allowed estimates of the reversible and irreversible enthalpy components to be made under flow conditions. Adsorption selectivity of the derivatised aluminosilicates changes when passing from one adsorption system to another. Both Ag(I) and Cu(II) can give selective adsorption of propene over propane under experimental conditions close to the adsorption equilibrium, whereas only Ag-containing samples are selective under flow conditions.

Activation of a carbon–carbon bond in solution by transition-metal insertion

CLEAVAGE of carbon–carbon bonds by transition-metal-containing heterogeneous catalysts forms the basis of one of the most important industrial processes, the refining of petroleum to chemicals and fuels1. But the generally low product selectivity observed with heterogeneous systems is a significant drawback. For this reason, much effort has been devoted to developing transition-metal complexes that can be inserted into C–C bonds in homogeneous media, as such catalysts can operate under mild, easily controlled conditions and might offer high selectivity and reactivity. Metal insertion into C–H bonds is well known2,3–5, but, except in a few special cases2,6–12, C–C bonds are generally unreactive towards insertion of transition metals in solution. Here we report the selective activation of a simple C–C bond by a mononuclear rhodium complex in a neutral homogeneous medium (tetrahydrofuran solution). We are able to effect Rh insertion into a C–C bond in a diphosphinoxylene, in which this bond is favourably oriented towards the transition-metal centre. The competing reaction of insertion into C–H is suppressed by the use of an overpressure of H2. We suggest that this approach might lead to a general strategy for C–C activation in homogeneous systems.

Insertion of transition metals into the phosphorus-phosphorus bond of 1,2-dihydro-1,2-diphosphetes: toward the phosphorus analogs of metal dithiolene complexes

The insertion of NiL 2 (L=phosphine) into the P-P bond of 1,2,3,4-tetraphenyl-1,2-dihydro-1,2-diphosphete has been achieved via two methods. In the first, the P-P bond is initially cleaved with lithium and the derivatized dianion allowed to react with [NiCl 2 L 2 ]. The yields primarily a nickeladiphospholene with a distorted square-planar geometry.

ChemInform Abstract: A New Class of Inorganic Heterocycles from Insertion of Transition Metals into the Cyclophosphazene Skeleton. Synthesis and Characterization of Six‐Membered Rings with Vanadium, Tungsten, and Rhenium in High Oxidation States.

AbstractThe cyclometallaphosphazenes (Ia)‐(Id) are prepared from the linear phosphazene salt (III) and the corresponding metal halides (II), (IV), and (V).

A new class of inorganic heterocycles from insertion of transition metals into the cyclophosphazene skeleton - synthesis and characterization of six-membered rings with vanadium, tungsten, and rhenium in high oxidation states

Le sel [H 2 NPPh 2 NPPh 2 NH 2 ] + Cl − reagit avec VCl 4 , WBr 4 , WF 6 et ReCl 5 forme des cyclometallaphosphazenes. Etude de la reaction, d'echange d'halogene sur le cyclotungstaphosphazene. Donnees RMN de 19 F, 31 P et 51 V

Transition-metal insertion into naked metal cluster polyanions

Transition-metal insertion into naked metal cluster polyanions