Properties Of Rhodium Research Articles

Synthesis, Structure, and Properties of Rhodium(II) Acetate Complexes with 2H-Azirines

Synthesis, Structure, and Properties of Rhodium(II) Acetate Complexes with 2H-Azirines

Tuning the optoelectronic properties of hematite with rhodium doping for photoelectrochemical water splitting using density functional theory approach

Hematite (Fe2O3) is one of the best candidates for photoelectrochemical water splitting due to its abundance and suitable bandgap. However, its efficiency is mostly impeded due to the intrinsically low conductivity and poor light absorption. In this study, we targeted this intrinsic behavior to investigate the thermodynamic stability, photoconductivity and optical properties of rhodium doped hematite using density functional theory. The calculated formation energy of pristine and rhodium doped hematite was − 4.47 eV and − 5.34 eV respectively, suggesting that the doped material is thermodynamically more stable. The DFT results established that the bandgap of doped hematite narrowed down to the lower edge (1.61 eV) in the visible region which enhanced the optical absorption and photoconductivity of the material. Moreover, doped hematite has the ability to absorb a broad spectrum (250–800) nm. The enhanced optical absorption boosted the photocurrent and incident photon to current efficiency. The calculated results also showed that the incorporation of rhodium in hematite induced a redshift in optical properties.

Rhodium doped InGaAs: A superior ultrafast photoconductor

The properties of rhodium (Rh) as a deep-level dopant in InGaAs lattice matched to InP grown by molecular beam epitaxy are investigated. When InGaAs:Rh is used as an ultrafast photoconductor, carrier lifetimes as short as 100 fs for optically excited electrons are measured. Rh doping compensates free carriers so that a near intrinsic carrier concentration can be achieved. At the same time, InGaAs:Rh exhibits a large electron mobility of 1000 cm2/V s. Therefore, this material is a very promising candidate for application as a semi-insulating layer, THz antenna, or semiconductor saturable absorber mirror.

Solubility of rhodium in dore metal

The solubilities of rhodium (Rh) in a molten silver alloy in dore-smelting conditions for treating copper refinery slime at temperatures of 1,000 to 1,300°C were measured using a high-temperature equilibration-quenching technique and direct phase analysis by electron probe X-ray microanalysis. The results obtained indicate that the solubility of rhodium in molten silver is very limited: only 0.04 to 0.26 weight percent at 1,000 and 1,300°C, respectively. The thermodynamic properties of rhodium in molten silver were estimated from the solubility data. The compositions of the solid rhodium alloys in equilibrium with molten silver-rich dore metal were also measured in this study. The excess rhodium in the dore alloy will precipitate during the refining as solid, greater than 99 weight percent Rh.

Electrochemical properties of rhodium- and gold-containing polyaniline films

Graphite-supported polyaniline films (PANI) containing rhodium particles were obtained by two procedures: metal electrodeposition on a prepared PANI film and electropolymerization. The adsorption/desorption and electrowinning of hydrogen on these films were observed for both types of synthesized composite films. PANI/Au composites were synthesized using the PANI films deposited onto a gold electrode. High anode potentials were further applied to the electrode in the presence of chloride ions, leading to a dissolution of gold and its transfer to the films during subsequent electroreduction. The amounts of the chloride complexes of gold formed in this procedure were determined by cyclic voltammetry of their electroreduction.

Ethanol steam reforming over rhodium and cobalt-based catalysts: Effect of the support

The effect of support on the properties of rhodium and cobalt-based catalysts for ethanol steam reforming was studied in this work, by comparing the use of magnesia, alumina and Mg–Al oxide (obtained from hydrotalcite) as supports. It was found that metallic rhodium particles with around 2.4–2.6 nm were formed on all supports, but Mg–Al oxide led to the narrowest particles size distribution; cobalt was supposed to be located on the support, affecting its acidity. Rhodium interacts strongly with the support in the order: alumina> Mg–Al oxide > magnesia. The magnesium-containing catalysts showed low ethene selectivity and high hydrogen selectivity while the alumina-based ones showed high ethene selectivity, assigned to the Lewis sites of alumina. The Mg–Al oxide-supported rhodium and cobalt catalyst was the most promising sample to produce hydrogen by ethanol reforming, showing the highest hydrogen yield, low ethene selectivity and high specific surface area during reaction.

Use of quantum-chemical methods in selecting catalysts for the removal of carbon and nitrogen oxides from exhaust gases

Carbon and nitrogen oxides contained in automobile exhaust gases are among the most hazardous air pollutants. Therefore, the search for new methods of the neutralization of noxious substances in exhaust gases is an urgent problem. Catalytic purification is among the most promising methods. The aim of this work is to show the applicability of quantum-chemical methods to the study of the mechanisms of NO x reduction and CO oxidation on the Rh-catalyst surface. A faujasite zeolite was used as the carrier. Calculations showed that the support enhances the electrophilic properties of rhodium and, thus, improves its catalytic activity.

Synthesis and Properties of Rhodium(III) Porphyrin Cyclic Tetramer and Cofacial Dimer

Rhodium(III) porphyrin complexes, [Rh(4-PyT(3)P)Cl](4) (1) and [Rh(2-PytB(3)P)Cl](2) (2) (4-PyT(3)P = 5-(4-pyridyl)-10,15,20-tritolylporphyrinato dianion, 2-PytB(3)P = 5-(2-pyridyl)-10,15,20-tri(4-tert-butyl)phenylporphyrinato dianion), were self-assembled and characterized by (1)H nuclear magnetic resonance spectroscopy, infrared spectroscopy, and electron spray ionization-mass spectroscopy methods. The spectroscopic results certified that the rhodium porphyrin complexes 1 and 2 have a cyclic tetrameric structure and a cofacial dimeric structure, respectively. The X-ray structure analysis of 1 confirmed the cyclic structure of the complex. The Soret bands of both oligomers were significantly broadened by excitonic interactions between the porphyrin units, compared to those observed for a corresponding analogue of Rh(TTP)(Py)Cl (TTP = 5,10,15,20-tetratolylporphyrinato dianion, Py = pyridine). Stepwise oxidation of the porphyrin rings in the oligomers was observed by cyclic voltammetry. The oligomers 1 and 2 are very stable in solution, and they slowly undergo reactions with pyridine to give corresponding monomer complexes only at high temperatures (approximately 80 degrees C).

Thermal properties of rhodium(III) chloride

Thermal decomposition of rhodium(III) chloride under inert, oxidative and reductive gas atmospheres was investigated in order to determine its thermal properties. Stoichiometries of the reactions occurring during heating are described. it is suggested that the chemical formula of soluble rhodium(III) chloride should be presented as RhCl3·HCL·xH2O. Cold crystallisation of anhydrous rhodium(III) chloride at a temperature of about 500°C was established. The procedure for quantitative determination of volatile matter (water and hydrochloric acid) content and rhodium content by thermogravimetry is given and discussed. The repeatability and reproducibility of the method are estimated.

Redox properties of rhodium(III) oxo-bridged carboxylate complexes

Chemical and electrochemical oxidation of rhodium (III) oxo-bridged carboxylate complexes was studied. The chemical [with O-3 and Ce(IV) salts] or electrochemical (at potentials of 1.00-1.20 V) oxi ...

Properties of rhodium (II) complexes having cytostatic activity

Dimeric rhodium (II) carboxylate complexes [Rh 2(OOCR) 4L 2], [Rh 2(OOCR) 2(NN) 2L 2] 2+ and [Rh 2Cl 2(RCOO) 2(NN) 2] (R  PhCH(OH), MeCH(OH), HOOCCH(OH)CH(OH), Me; NN  2,2′-bipyridine, 1,10-phenanthroline) have been synthesized and characterized using electronic, NMR, and IR spectra. Cytostatic activity of these complexes has been tested for human oral carcinoma KB cell line. Some complexes with hydroxycarboxylates and [Rh 2(RCOO) 2(NN) 2] 2+ compounds show higher cytostatic activity than [Rh 2(OOCCH 3) 4(H 2O) 2].

Synthesis and catalytic properties of rhodium(I) complexes with anionic chelate nitrogen-oxygen ligands

Dicarbonyl complexes of rhodium(I) [Rh(CO)2(LL′)], where LL′ = salicylaldoximate, 8-oxyquinolinate, glycinate, leucinate, aminophenolate or pyridine carboxylate and [Rh(COD)(LL′)], where COD = 1,5-cyclooctadiene, were prepared and characterized by elemental analysis, and i.r. and n.m.r. spectra. Their activity to catalytic hydroformylation of styrene has been evaluated at atmospheric pressure of CO∶H2(1∶1).

Preparation and Properties of Rhodium(III) Complexes with the Tetradentate Ligand N,N'-Bis(2'-pyridinecarboxamide)-1,8-naphthalene

Abstract Synthetic procedures are described that allow access to a number of new Rh(III) complexes with the tetradentate bis-amide ligand N,N'-bis(2'-pyridinecarboxamide)-1,8-naphthalene (LH2). These complexes have the formulae Rh(LH2)Cl3, Na[RhLX2] • H2O (X = Cl, CN) and [RhLA2]ClO4 (A = pyridine, 1-methylbenzotriazole). The compounds have been characterized by elemental analyses, conductivity measurements, X-ray powder patterns, spectroscopic (IR, UV/VIS, 1H NMR) studies and electrochemical methods. The neutral amide behaves as a bis-bidentate ligand in the oligomeric or polymeric, octahedral complex Rh(LH2,)Cl3. Monomeric, trans octahedral structures are assigned for the complexes of L2− in the solid state; the doubly deprotonated ligand acts as a tetradentate chelating agent with the four nitrogens as ligating atoms.

Synthesis and properties of rhodium(I) chloranilate and 2,5-dihydroxy-1,4-benzoquinonate complexes. Crystal structures of the binuclear [Rh2(.mu.-CA)(cod)2] and tetranuclear [Rh4(.mu.-CA)2(cod)4] complexes (CA = chloranilate anion)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and properties of rhodium(I) chloranilate and 2,5-dihydroxy-1,4-benzoquinonate complexes. Crystal structures of the binuclear [Rh2(.mu.-CA)(cod)2] and tetranuclear [Rh4(.mu.-CA)2(cod)4] complexes (CA = chloranilate anion)Miguel A. Calvo, Anna Maria Manotti Lanfredi, Luis A. Oro, M. Teresa Pinillos, Cristina Tejel, Antonio Tiripicchio, and Franco UgozzoliCite this: Inorg. Chem. 1993, 32, 7, 1147–1152Publication Date (Print):March 1, 1993Publication History Published online1 May 2002Published inissue 1 March 1993https://doi.org/10.1021/ic00059a021RIGHTS & PERMISSIONSArticle Views250Altmetric-Citations43LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (787 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Particle size, precursor, and support effects in the hydrogenolysis of alkanes over supported rhodium catalysts

A series of Rh catalysts of widely varying dispersion has been prepared using γ-alumina as support and Rh acetylacetonate (Rh(acac) 3) as precursor. The hydrogenolyses of n-hexane ( nH), methylcyclopentane (MCP), and 2,2,3,3-tetramethylbutane (TeMB) were investigated as model reactions. Clear dependence of turnover frequency on Rh particle size is observed for nH and MCP hydrogenolysis, but only slight changes of selectivities occur with these alkanes. By contrast, large modifications of both specific activity and selectivity appear when TeMB is reacted. TeMB hydrogenolysis is thus a reliable tool for studying modifications of the surface structure of rhodium particles. This probe was used to investigate the effects of precursor and support on rhodium catalysts. The effect of chlorine is appreciable and shifts the selectivity of TeMB hydrogenolysis toward that of large particles. This is attributed to a different morphology of the rhodium particles. When the effect of dispersion of the metal is taken into account, no support effect is observed when SiO 2 or ZrO 2 is used as support. The different properties of rhodium on MgO can also be attributed to a different morphology of the particles. For Rh/TiO 2 prepared from RhCl 3 · 3H 2O, the catalytic properties are similar to those of Rh/Al 2O 3 of moderate dispersion whatever temperature is used for reduction. Rh/TiO 2 prepared from Rh(acac) 3 and reduced at 573 and 773 K simulates the catalytic properties of particles smaller than indeed observed. This effect can be interpreted by a partial coverage of the Rh surface by TiO x species (SMSI). This SMSI effect disappears upon eduction at 873 K.

Rhodium(I) complexes with pyridazine, 4,6-dimethyl-pyrimidine, 4,6-bis(3,5-dimethylpyrazol-1-yl)pyrimidine, 3,6-bis(3,5-dimethylpyrazol-1-yl)pyridazine and 3-(3,5-dimethylpyrazol-1-yl)-6-chloropyridazine

The synthesis and properties of rhodium(I) complexes of formulae [“RhCl(diolefin)” 2(L)] (or [Rh(Cl(diolefin)(L)]), and [Rh(diolefin)(L)] n (ClO 4) n are reported. These complexes react with carbon monoxide to yield the related carbonyl derivatives. Ligands used were pyridazine, 4,6-dimethyl-pyrimidine, 4,6-bis(3,5-dimethylpyrazol-1-yl)pyrimidine, 3,6-bis(3,5-dimethylpyrazol-1-yl)pyridazine and 3-(3,5-dimethyl-pyrazol-1-yl)-6-chloropyridazine. Related iridium(I) and gold(I) compounds are also reported.

Hydrocarbon conversion on promoted rhodium/Al2O3 catalysts

In (E+Rh)/Al2O3 catalysts (E=Sn, Pb, Mo and W) the catalytic properties of rhodium in benzene hydrogenation, propane hydrogenolysis and n-hexane conversion change drastically. For modified rhodium the decrease in the hydrogenolysis rate of C−C bonds in paraffins leads to an increased yield of the products of non-destructive conversion of n-hexane.

A knudsen cell study of molten sulfides: Thermodynamics of the Rh-S system

A Knudsen cell method for determining sulfur pressures in liquid matte systems is described which allows a range of compositions to be studied in a short time. The change in weight with time of the cell due to effusion of sulfur is used to follow the composition of the matte and determine the sulfur pressure at the same time. The method has been tested using Ni-S mattes and then applied to the Rh-S system. From the results the standard free energy of formation, ΔT0, of Rh17S15 was found to be − 300200 + 154.75T J/mole S2 (1213 to 1363 K). Partial molar properties of rhodium and sulfur have also been derived. Liquidus temperatures determined from the Knudsen effusion experiments compare favorably with results from DTA, and a phase diagram for the Rh-S system is presented.

Modification of catalytic properties of silica-supported rhodium

A sharp change in the catalytic properties of rhodium in benzene hydrogenation, propane hydrogenolysis and n-hexane conversion has been found for catalysts prepared via interaction between Rh(CO)2Cl2 and silica modified by Sn, Pb, Mo and W ions.

Preparation and properties of rhodium(I) complexes of phosphinated poly(methylsiloxanes)

A series of poly(methylsiloxanes) that contain carbon-functional diphenylphosphine groups were prepared and subsequently treated with RhCl(CO)(PPh 3) 2 to produce polymer-attached chlorocarbonylrhodium(I) complexes. The materials are soluble in a variety of organic solvents, and are easily precipitated from solution by the addition of excess methanol. The polymer complex A derived from a phosphinated silicone polymer containing one PPh2 group per 60 siloxy units has a molecular weight of 21000 daltons and contains 0.8% Rh. In accord with its formulation, the polymer shows a ν(CO) at 1970 cm -1 and an ultraviolet absorption at 3625 Å. Similar rhodium(I) complexes derived from phosphinated silicones containing one PPh 2 group per 20 (complex B) and 8 (complex C) siloxy units were also investigated. Complexes A and B catalyze the hydroformylation of hex-1-ene at 100°C, 1000 psi CO/H 2 pressure yielding the linear/branched heptaldehyde in a ratio of 0.9 with 95% selectivity and an overall conversion of 97% to products in 3 h. Although the hydroformylation conditions do not lead to depolymerization, both Rh and P are lost from the polymers and the actual catalyst appears to be a free rhodium carbonyl species. Complex C is a less active hydroformylation catalyst (14% aldehyde conversion, normal/branched ratio 1.7) and the polymer undergoes extensive degradation in the reaction.