Reactions of Dinitrogentrioxide with Rhodium(I) Complexes and with Rhodiumtrichloride trihydrate in presence of triphenylphosphine and triphenylarsine

Dinitrogen-trioxide reacts with rhodium(I) complexes and with rhodium trichloride trihydrated in presence of triphenylphosphine and triphenylarsine to give rhodium(III) nitrosylnitro complexes and rhodium(III) nitrosyl complexes which are characterized by ir spectra, magnetic measurement and elemental analyses.     

Study on the Interactions of Ruthenium(III), Rhodium(III) and Palladium(II) Ions with DNA

Fluorescence, absorption and circular dichroism spectra have been used in the interactions of ruthenium(III), rhodium(III) and palladium(II) ions with DNA with berberine as a probe (berberine, Scheme 1). The results are as follows: ruthenium(III) and rhodium(III) ions show different effects from that of the palladium(II) ion on the fluorescence spectra characteristics of berberine-DNA system. Quenching fluorescence is seen with palladium(II) ion addition, whereas increasing fluorescence is observed for ruthenium(III) and rhodium(III) ions. The addition of ruthenium(III), rhodium(III) and palladium(II) ions causes the increasing absorption of the DNA solution. The addition of ruthenium(III), rhodium(III) and palladium(II) ions to the DNA solution also causes the circular dichroism spectra to change. The above results suggest that different metal ions exhibit different affinity when binding to DNA, which could correlate well with the ions’ charge, structure and the ability to coordinate. There is a comparison between Pt(IV) and Pd(II) ions on the fluorescence of the berberine-DNA system.     

Reaction of nitrosyltribromide with rhodium(I) complexes and with rhodiumtrichloride trihydrate,in the presence of triphenylphosphine and triphenylarsine

Summary Nitrosyltribromide reacts with rhodium(I) complexes and with rhodiumtrichloride trihydrate in the presence of triphenylphosphine and triphenylarsine to give rhodium(III) nitrosyl complexes and rhodium(III) hyponitrite complexes which are characterized by i.r. spectra, magnetic measurements and by elemental analyses.     

Study of the Speciation of Rhodium(III) in a Hydrochloric Acid Solution by Capillary Electrophoresis

The possibility of studying the speciation of rhodium(III) by capillary electrophoresis was shown using a model solution of rhodium(III) in 0.1 M HCl as an example. The revealed rhodium species were identified by their absorption spectra. The effect of the pH, ionic strength, and metal (Me) cation in the HCl–MeCl supporting electrolyte on the migration parameters and the speciation of rhodium(III) in the solution was studied.     

Synthesis and reactions of rhodium compounds containing tellurium donor ligands

This paper describes the synthesis and characterization of a series of rhodium(I) and rhodium(III) complexes containing tellurium-rhodium bonds resulting from the coordination of diorgano telluride or organotelluro ligands. Oxidative addition, metathesis and substitution reactions of these compounds have been examined, and the resulting products are compared with those from the known reactions of rhodium(I) and rhodium(III) compounds containing phosphine ligands.     

Preparation of Colloidal Rhodium in Poly(vinyl Alcohol) by Reduction with Methanol

Refluxing of a solution of poly(vinyl alcohol) and rhodium(III) chloride in methanol-water gives a colloidal dispersion of rhodium which is an effective catalyst for hydrogenation of cyclohexene in methanol at 30°C under atmospheric hydrogen pressure. Formaldehyde is produced quantitatively with the reduction of rhodium(III) chloride to metallic rhodium. The rhodium particles in the colloidal dispersion are found to consist of two kinds of particles, about 8 and 40 Å in diameter by electron microscopy. The sizes of the small (8 Å) and large (40 Å) particles are almost constant during the course of refluxing. The number of small particles, which is the great majority of particles at the early stage of refluxing, gradually decreases; concurrently the number of large particle increases on prolonged refluxing. An absorption peak appears at 260 nm at the early stage of refluxing. The presence of the 260 nm peak, which indicates the coordination of poly(vinyl alcohol) to rhodium(III) ion, is indispensable for the formation of a homogeneous colloidal dispersion of rhodium. The addition of ethylenediamine inhibits the formation of colloidal rhodium in refluxing. The catalytic activity of colloidal dispersion of rhodium is dependent upon the concentration of rhodium(III) chloride charged and is independent of that of poly(vinyl alcohol). The formation mechanism of colloidal rhodium is discussed.     

Reactions of ruthenium(III), Rhodium(III) and Iridium(III) chlorides in molten nitrite eutectics

The reactions of ruthenium(III), rhodium(III) and iridium(III) chlorides in molten lithium nitrite—sodium nitrite, lithium nitrite—potassium nitrit and sodium nitrite—potassium nitrite eutectics were studied and compared with those of their first row congeners. Ruthenium(III) reacted to form hexanitroruthenate(II) with the evolution of nitrogen dioxide, whereas rhodium(III) and iridium(III) formed hexanitrorhodate(III) and hexanitroiridate(III), respectively. These complexes decomposed at higher temperatures to form ruthenium(IV), rhodium(III) and iridium(IV) oxides, respectively, with the evolution of nitrogen oxides. The stoichiometries of these reactions were established by thermogravimetry and the products were characterized by their IR, visible and UV spectra, and X-ray diffraction patterns.     

Extraction of rhodium(III) by 1,3-diamyl-2-imidazolidinethione from hydrochloric acid solutions

The extraction of rhodium(III) with 1,3-diamyl-2-imidazolidinethione from hydrochloric acid solutions was studied. Optimum conditions for rhodium(III) extraction were determined. It was found that rhodium(III) was extracted from a 0.5 M solution of HCl at a phase contact time of 3 h by a coordination mechanism. The composition of the extracted compound was determined using electronic, ¹H and ¹³C NMR, and IR spectroscopy and elemental analysis. It was demonstrated that the extracting agent coordinated to the rhodium(III) ion through the sulfur atom.     

Development of a Liquid‐liquid Extraction System for Rhodium(III) by 2‐octylaminopyridine from Weak Malonate Media

We have developed the extraction method of rhodium(III) from malonate media with 2‐octylaminopyridine (2‐OAP) in xylene at pH 8.0. The quantitative extraction of rhodium(III) with extractant was found by screening of different physicochemical parameters like malonate concentration, extractant concentration, pH, diluents, effect of temperature, aq: org phase ratio, loading capacity of 2‐OAP. The optimum condition was malonate=0.025 M, pH=8.0, 2‐OAP=0.05 M in xylene. The complete stripping of rhodium(III) from the loaded organic phase was carried out with 2 M HCl. Log‐log plot was investigated to determine the stoichiometry of the extracted species and it was found to be 1 : 2 : 1 (metal : acid :extractant). The versatility of the proposed method was checked for extraction and separation of rhodium(III) from binary, ternary mixture of associated metal ions as well as platinum group metals and from the synthetic solution of rhodium minerals and alloys.     

Extraction of rhodium(III) by a bisacylated diethylenetriamine derivative from hydrochloric acid solutions

The extraction of rhodium(III) with a bisacylated diethylenetriamine derivative from hydrochloric acid solutions was studied. Optimum conditions for rhodium(III) extraction were determined. It was found that, at a contact time to 10 min, the extraction occurred by an ion-association mechanism. At a contact time longer than 10 min, rhodium(III) was extracted by a mixed mechanism with the insertion of an extractant molecule into the inner coordination sphere of the rhodium(III) ion. The composition of the extracted compound was determined using electronic, ¹H and ¹³C NMR, and IR spectroscopy and elemental analysis, and the structure of this compound was proposed.     

Studies on optimization of conditions for separating rhodium and platinum by cation-exchange

It has been established that, owing to the amphoteric properties of rhodium(III) hydroxide, by making a rhodium chloride solution alkaline (pH approximately 13) with sodium hydroxide and then acidifying to pH 2 with nitric acid it is possible to convert at least 99% of the rhodium into cationic forms. This fact is utilized for separation of rhodium(III) and platinum(IV) from chloride solutions on a sulphonic acid cation-exchanger in hydrogen form. Loss of rhodium in the separation process is < 1%. Platinum elution is complete. This method is suitable for separation of mixtures of rhodium and platinum (present in molar ratio between 1:200 and 20:1).     

Chloride‐Bridged Dinuclear Rhodium(III) Complexes Bearing Chiral Diphosphine Ligands: Catalyst Precursors for Asymmetric Hydrogenation of Simple Olefins

Efficient rhodium(III) catalysts were developed for asymmetric hydrogenation of simple olefins. A new series of chloride‐bridged dinuclear rhodium(III) complexes 1 were synthesized from the rhodium(I) precursor [RhCl(cod)]₂, chiral diphosphine ligands, and hydrochloric acid. Complexes from the series acted as efficient catalysts for asymmetric hydrogenation of (E)‐prop‐1‐ene‐1,2‐diyldibenzene and its derivatives without any directing groups, in sharp contrast to widely used rhodium(I) catalytic systems that require a directing group for high enantioselectivity. The catalytic system was applied to asymmetric hydrogenation of allylic alcohols, alkenylboranes, and unsaturated cyclic sulfones. Control experiments support the superiority of dinuclear rhodium(III) complexes 1 over typical rhodium(I) catalytic systems.     

Differential catalytic determination of iridium(IV) and rhodium(III) based on the oxidation of N-methyldiphenylamine-4-sulfonic acid

The kinetics of the oxidation of N-methyldiphenylamine-4-sulfonic acid with periodate ions was studied in weakly acidic solutions in the presence of iridium(IV), rhodium(III), and their mixtures. Oxidation rate constants were determined in the presence of individual catalysts and their mixtures. The synergetic effect of iridium(IV) and rhodium(III) on the rate of the indicator reaction was estimated; the range of catalyst ratios for the simultaneous determination of analytes was determined. The effect of some factors (oxidant nature and concentration, temperature, the ionic strength of solution, and interfering ions) on the rate of the indicator reaction in the presence of iridium(IV) and rhodium(III) mixtures was assessed. A procedure for the differential catalytic determination of iridium(IV) and rhodium(III) was proposed and tested in the analysis of artificial mixtures and a platinum concentrate of complex composition (KP-5).     

Effect of ring methylation on the photophysical, photochemical and photobiological properties of cis-dichlorobis(1,10-phenanthroline)rhodium(III)Chloride

Methylated analogues of cis-dichlorobis(1,10-phenanthroline)rhodium(III)chloride (BISPHEN) have been prepared in order to increase the hydrophobicity of the parent compound, and thus create octahedral rhodium (III) complexes suitable for use as anticancer and antiviral agents that can be photoactivated. The parent complex has been shown in earlier work to be unable to cross through cell membranes. Octamethylation, as in the case of cis-dichlorobis(3,4,7,8-tetramethyl-1,10-phenanthroline)rhodium(III)chloride (OCTBP), provides enough hydrophobicity to be taken up by KB tumor cells. It also provides a higher level of ground-state association with double-stranded DNA and increases the quantum efficiency of photoaquation by greater than 10-fold, relative to BISPHEN. OCTBP forms covalent bonds to deoxyguanosine when irradiated with the nucleoside, as has been seen with the parent complex. Irradiation of OCTBP in the presence of the KB or M109 tumor cell lines using narrow-band UVB (lambda = 311 nm) irradiation initiates a considerable amount of phototoxicity. There is evidence that OCTBP acts as a prodrug (i.e. after passing through the cell membrane the metal complex is photolyzed to cis-chloro aquo OCTBP, which may be the active phototoxic agent). OCTBP and the tetramethyl analogue cis-dichlorobis(4,7-dimethyl-1,10-phenanthroline)rhodium(III)chloride (47TMBP) also show photoaquation upon excitation with visible light (lambda > 500 nm), and indeed, some phototoxicity of KB cells is observed at these wavelengths as well. This is attributed to direct population of photoactive triplet-excited states. These results, together with our earlier studies of cis-dichloro[dipyrido(3,2-a: 2',3'-c)phenazine (1,10-phenanthroline)rhodium(III)chloride (DPPZPHEN) demonstrate that such octahedral rhodium complexes are viable "photo-cisplatin" reagents.     

Metal complexes of isonicotinic acid hydrazide

Complexes of platinum(IV), ruthenium(III), rhodium(III), iridium(III), gold(III), dioxouranium(II), zinc(II), cadmium(II), mercury(II) and manganese(II) with isonicotinic acid hydrazide were prepared and characterized on the basis of analytical, conductometric, magnetic susceptibility and spectral data. Platinum(IV) ruthenium(III), rhodium(III), iridium(III), dioxouranium(II) and manganese(II) form six-coordinate complexes while gold(III), zinc(II), cadmium(II) and mercury(II) form four coordinate complexes.     

Efficient electrochemical conversion of carbon monoxide by rhodium octaethylporphyrin adsorbed on carbon black

We have found efficient electrocatalytic removal of CO by rhodium octaethylporphyrin on carbon black at a wide potential range. Using carbon-supported rhodium octaethylporphyrin, we have separated the Rh(II) state participating reaction and the Rh(III) state participating reaction with CO. We have clearly demonstrated electrocatalytic CO oxidation by rhodium(III) porphyrin. The onset potential for CO oxidation is much lower than that for CO oxidation by conventional Pt/Ru catalysts and cobalt porphyrin.     

Activation of aliphatic carbon-carbon bonds of esters and amides by rhodium(II) porphyrin

Aliphatic carbon-carbon bonds of esters and amides were activated successfully with rhodium(II) porphyrin radical to give rhodium(III) porphyrin alkyls in moderate yields.     

Polyurethane foams as selective sorbents for noble metals : Quantitative extraction and separation of rhodium from iridium in hydrochloric acid containing tin(II) chloride

The distribution of rhodium(III) between polyether-type polyurethane foam and 0.5–5.0 mol dm^?3 hydrochloric acid in the presence of small amounts of tin(II) chloride is described. The distribution of rhodium is affected by the extraction temperature, acid concentration and the Sn(II):Rh ratio. The capacity of the polyurethane foam for rhodium is in excess of 0.5 mmol g^?1. Rhodium is presumably sorbed in the form of a chloro(trichlorostannato)rhodium(III/I) complex anion. Iridium is not extracted by the foam under corresponding conditions and can be separated quantitatively from rhodium.     

Solvent extraction separation of rhodium(III) with N-n-octylaniline as an extractant

Solvent extraction separation method for the determination of rhodium(III) has been described. Selective and quantitative extraction of rhodium(III) by N-n-octylaniline, a high molecular weight amine (HMWA) into xylene takes place from aqueous sodium malonate medium. The effect of concentration of malonate, N-n-octylaniline, role of various diluents, stripping agents and foreign ions on the extraction of rhodium(III) has been studied. The procedure offers distinct improvements in need of real sample analysis and environmental safety as the extraction procedure carried out in weak organic acid media.     

Liquid-liquid extraction of rhodium(III) from hydrochloric acid solutions with 1,2,4-triazole derivative

Liquid-liquid extraction of rhodium(III) from hydrochloric acid solutions with a 1,2,4-triazole derivative was studied. Optimal conditions for its recovery were found. Rhodium(III) was shown to be recovered in extraction system by ion-exchange reaction at the time of phase contact not longer than 5 min. When phase contact time increased, rhodium(III) is extracted by a mixed mechanism with simultaneous insertion of two extractant molecules into the inner coordination sphere of rhodium(III) ion. Composition of coordination species of recovered compounds was established by electronic, IR, ¹H and ¹³C NMR spectroscopy and functional analysis, the structure of the coordination species is proposed.