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An expedient Rh(III)-catalytic method has been described to synthesis of 2-nitro-2 H -azirine derivatives from easily accessible β -nitrooxime ethers via sp3 C–H activation process. This protocol features of low catalyst loading, very mild reaction conditions, and tolerating a diverse of functionalities in good yields. A possible reaction pathway is proposed involving [RhCp*Cl2 ]2-catalyzed sp3 C–H bond activation and pivalic acid elimination steps. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rh(III)(>80%) can be extracted at high acidity by using [C 8 DABCO][NTf 2 ]. • The system avoids the use of organic solvents and SnCl 2. • The extraction mechanism was illustrated. • The system has very high selectivity to extract Rh from the multi-metal solution. • The single-stage stripping efficiency is as high as 88%. Rhodium, as a rare precious metal, has always been a challenge for the chemical industry to efficiently recover rhodium by extraction due to the complex existing situation in hydrochloric acid medium. Herein, a strongly hydrophobic DABCO-based ionic liquid (IL) [C 8 DABCO][NTf 2 ] was designed and synthesized to construct a solvent-free extraction system of Rh(III) from high-concentration hydrochloric acid medium. At first, the effects of some important parameters on Rh(III) extraction were studied, such as equilibrium time, IL dosage, hydrochloric acid concentration, and initial Rh(III) concentration, the results showed that 81.54% Rh(III) can be extracted under the optimum extraction conditions. Based on the experimental run results, a quadratic model equation was established by using the response surface method (RSM), which can be used to calculate the amount that [C 8 DABCO][NTf 2 ] will be offered at various HCl concentrations during the actual extraction of Rh(III). Then, using Job's method, the Ultraviolet visible spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FT-IR), Energy-dispersive X-ray spectroscopy (EDS), and Electrostatic potential (ESP) prove that the extraction mechanism is an anion exchange mechanism. Finally, in the mixed solution of multi-metals, the extraction efficiency of [C 8 DABCO][NTf 2 ] for Rh(III) is not disturbed, and the extraction efficiency for other metals is less than 1%. And the single-stage stripping efficiency of Rh(III) was up to 88% through HCl stripping, which solved the problem of difficult stripping of Rh(III) solution and realized the recycling of IL. The study provides a reliable and efficient way for recovering Rh(III) from high-concentrations HCl solutions. [ABSTRACT FROM AUTHOR]

In this work, the aqueous speciation of Rh(III) in chloride medium was investigated by UV-vis spectroscopy for ligand to metal ratios R = (Cl−)/(Rh) ranging from 300 to 5000, at fixed Rh concentration (2.4 × 10−3 M). Under the chemical conditions of this work, no time evolution was observed, which allows for the fitting of the UV-vis data by Principal Component Analysis (PCA) and Multi-Curve Resolution (MCR). From this, and by comparison with literature data, the three independent species [RhCl4]−, [RhCl5]2− and [RhCl6]3− were identified, their individual absorption spectra derived and their respective contribution to the collected experimental UV-vis spectra calculated. Then, extraction of Rh(III) towards the ionic liquid trihexyltetradecylphosphonium chloride was performed. Comparison with the speciation data gives insight into the extraction mechanism and the extracted species.

Spectral (H NMR and IR), optical, and voltammetry parameters of Pd(II), Pt(II), Rh(III), and Ir(III) complexes with ethylenediamine and metallated azole luminophors [2-phenylbenzoxazole, 2-phenylbenzothiazole, 2,5-diphenyloxazole, 2-(1,1'-biphenyl)-4-yl]-5-phenyloxazole, and 2-(naphthalene-l-yl)benzothiazole] have been studied. The variation in spectroscopic parameters of the complexes is related to the increase in the efficiency of donor-acceptor interaction of Pt(II) and Ir(III) with the ligands as compared to Pd(II) and Rh(III). The correlation between the energy of the metal-ligand charge transfer bands and the difference between the single-electron oxidation and reduction potentials of the complexes is observed. Quenching of the fluorescence of metallated azoles and phosphorescence of the complexes in the visible region from the metal-modified intraligand excited state are related with the increase in the efficiency of the singlettriplet conversion due to the spin-orbital interaction in platinum metals. [ABSTRACT FROM AUTHOR]

A series of octahedral Ru(III), Rh(III) and Ir(III) complexes have been prepared with tetradentate Schiff bases derived by condensing isatin with 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,2-diaminobenzene and 1,3-diaminobenzene. The obtained complexes were characterized on the basis of their elemental analyses, magnetic moment, conductance, IR, electronic, 1HNMR and FAB mass spectra, as well as thermal analyses. The Ru(III) complexes are low spin paramagnetic, while Rh(III) and Ir(III) behave as diamagnetic complexes. The IR spectral data revealed that all the Schiff bases behave as tetradentate and are coordinated to Ru(III), Rh(III) and Ir(III) via nitrogen and oxygen. Antifungal studies of the ligands as well as their complexes were carried out by the agar plate method.

The influence of tin (II) chloride additives on sorption of Rh(III) on the Purolite S920 ion exchange resin with isothiouronium groups, the Purolite S985 weak base anion exchange resin, and the Purolite A500 strong base anion exchange resin is investigated. It is established that the introduction of SnCl leads to a substantial increase in selectivity of all tested ion exchange resins to Rh(III) and in the sorption rate of Rh(III) on S985 and S920 ion exchange resins. The optimal dosage of SnCl (0.01 mol/L) at which the distribution coefficients of Rh(III) during sorption for all tested ion exchange resins reach maximal values is determined. It is shown that almost quantitative recovery of Rh(III) is attained when passing the multicomponent chloride solution of the composition (g/L) 0.2 Rh(III), 72.9 HCl, 53.5 NHCl, 2.7 Al(III), 1.23 Fe(III) and 5.9 Sn(IV) with the SnCl additive through the Purolite S920 ion exchange resin with isothiouronium groups. Desorption of Rh(III) from the Purolite S920 saturated ionite with the acidified thiourea solution is incomplete, no greater than 60%. [ABSTRACT FROM AUTHOR]

The novel cyclometalated Rh(III) complex, [Rh(phpy) 2 (SˆS)], Where phpy is 2-phenylpyridine and (SˆS) is diethyldithiocarbamate, has been prepared and characterized by elemental analysis, IR, 13 C and 1 H NMR, electronic absorption and Fluorescence spectroscopies, cyclic voltammetry, and X-ray crystallography. The crystal structure of [Rh(phpy) 2 (SˆS)] shows that the coordination geometry around the Rh(III) is a distorted octahedron, with bite angles of 71.19–81.04° for all three bidentate ligands. Electrochemical analysis by cyclic voltammetry reveals irreversible redox behavior of the rhodium centre. Antibacterial activity of the complex has also been studied by agar disc diffusion method against three Gram-negative bacteria (Pseudomonas aeroginosa, Salmonella typhi and Escherichia coli ) and two Gram-positive bacteria ( Staphylococcus aureus and Corynebacterium renale). [ABSTRACT FROM AUTHOR]

A series of octahedral Ru(III), Rh(III) and Ir(III) complexes have been prepared with tetradentate Schiff bases derived by condensing isatin with 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,2-diaminobenzene and 1,3-diaminobenzene. The obtained complexes were characterized on the basis of their elemental analyses, magnetic moment, conductance, IR electronic, 1HNMR and FAB mass spectra, as well as thermal analyses. The Ru(III) complexes are low spin paramagnetic, while Rh(III) and Ir(III) behave as diamagnetic complexes. The IR spectral data revealed that all the Schiff bases behave as tetradentate and are coordinated to Ru(III), Rh(III) and Ir(III) via nitrogen and oxygen. Antifungal studies of the ligands as well as their complexes were carried out by the agar plate method.

Highlights: [•] 2,2′-Bisoxazoline complexes of Rh(III). [•] Binding of aminoalcohol to Rh(III). [•] Acid dissociation of coordinated alcohol. [•] Solution conductance. [•] pKa. [ABSTRACT FROM AUTHOR]

A novel Rh(III)-imprinted amino-functionalised silica gel sorbent was prepared by a surface imprinting technique for preconcentration and separation of Rh(III) prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Compared with the traditional solid sorbents and non-imprinted polymer particles, the ion-imprinted polymers (IIPs) had higher adsorption capacity and selectivity for Rh(III). The maximum static adsorption capacity of the imprinted and non-imprinted sorbent for Rh(III) was 29.86 mg g-1 and 11.23 mg g-1, respectively. The imprinted Rh(III) was removed with 2 mL of 3% thiourea + 2 mol L-1 HCl. The obtained imprinted particles exhibited excellent selectivity and rapid kinetics process for Rh(III). The relatively selective factor (αr) values of Rh(III)/Ru(III), Rh(III)/Au(III), Rh(III)/Pt(IV), Rh(III)/Ir(IV), Rh(III)/Pd(II) were 26.7, 39.0 29.2, 28.1, 43.7, respectively, which were greater than 1. The detection limit (3σ) of the method was 0.26 µg L-1. The relative standard deviation of the method was 1.79% for eight replicate determination of 10 µg of Rh3+ in 200 mL water sample. The method was validated by analysing standard reference material (GBW 07293), the results obtained is in good agreement with standard values. The developed method was also successfully applied to the determination of trace rhodium(III) in geological samples with satisfactory results. [ABSTRACT FROM AUTHOR]

Abstract: A novel tetradentate macrocyclic ligand viz. 1,5,8,13-tetraaza-2,9-dimethyl-4,11-diphenylcyclotetradeca-2,4,9,11-tetraene (L) and its complexes with PdII, PtII, RhIII and IrIII metal ions were synthesized. These complexes were characterized by elemental analysis, molar conductance, magnetic susceptibility measurements, IR and electronic spectral studies. On the basis of molar conductance and elemental analyses the general stoichiometries of the complexes were found to be [M(L)]Cl2 and [M′(L)Cl2]Cl, where M=Pd(II), Pt(II) and M′=Rh(III), Ir(III). The spectral studies reveal the four coordinated square planar geometry for PdII and PtII complexes and six coordinated octahedral geometry for RhIII and IrIII complexes. In vitro the synthesized ligand and its metal complexes have been screened for bactericidal and fungicidal activities using disc diffusion and food poison technique, respectively, at different concentrations. The organisms used in antibacterial investigation included Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and for antifungal investigation Aspergillus-niger, Aspergillus-glaucus, Fusarium odum. The antimicrobial data reveal that the metal complexes act more as bactericidal and fungicidal agents as compared to the uncomplexed ligand and the metal salts from which they derive. [ABSTRACT FROM AUTHOR]

Abstract: It was found that Rh, Pd and Pt contained in the spent ceramic automotive catalysts could be effectively extracted by dry chlorination with chlorine. In order to concentrate Rh(III) ions contained in the chloride solutions obtained, thermodynamic and kinetics studies for adsorption of Rh(III) complexes from the chloride solutions on an anionic exchange resin Diaion WA21J were carried out. Rh, Pd, Pt, Al, Fe, Si, Zn and Pb from the chloride solution could be adsorbed on the resin. The distribution coefficients (K d) of Rh(III) decreased with the increase in initial Rh(III) concentration or in adsorption temperature. The isothermal adsorption of Rh(III) was found to fit Langmuir, Freundlich and Dubinin–Kaganer–Radushkevich models under the adsorption conditions. The maximum monolayer adsorption capacities Q max based on Langmuir adsorption isotherms were 6.39, 6.61 and 5.81mg/g for temperatures 18, 28 and 40°C, respectively. The apparent adsorption energy of Rh was about −7.6kJ/mol and thus Rh(III) adsorption was a physical type. The experimental data obtained could be better simulated by pseudo-first-order kinetic model and the activation energy obtained was 6.54J/mol. The adsorption rate of Rh(III) was controlled by intraparticle diffusion in most of time of adsorption process. [Copyright &y& Elsevier]

The crystal structures of the Rh[(EtO)2PS2]3 (I) and Co[(PhO)2PS2]3 (II) chelate compounds were determined from X-ray diffraction (XRD) data (CAD-4 diffractometer, Mo K β radiation, 1193 F hkl , R = 0.0516 for I and 513 F hkl , R = 0.0305 for II). Crystals I are monoclinic: a = 14.233(3) Å, b = 13.570(3) Å, c = 14.272(3) Å; β = 90.66(3)°, V = 2756.3(10) Å3, Z = 4, ρcalc = 1.587 g/cm3, space group C2/ c. Crystals II are trigonal: a = 15.149(2) Å, c = 30.306(6) Å; V = 6023.2(16) Å3, Z = 6, ρcalc = 1.493 g/cm3, space group R3¯. Structures I and II consist of discrete mononuclear molecules. The coordination polyhedra of the M atoms (M = Rh, Co) are distorted octahedra formed by six sulfur atoms of three cyclic bidentate (RO)2 PS ligands. [ABSTRACT FROM AUTHOR]

The reaction of 2-(arylazo) aniline, 1 (HL-NH2) [where HL-NH2 is 2-(ArN=N)C6H4–NH2; Ar = C6H5 (for HL1-NH2), p-MeC6H4(for HL2-NH2) and p-ClC6H4(for HL3-NH2). H of HL stands for dissociable proton of Ar due to orthometallation], with Rh(PPh3)3Cl (Wilkinson’s catalyst) furnished the cyclometallated azoimine complexes of composition (L-NH)Rh(PPh3)2Cl (2). All the complexes were characterized by spectroscopic technique and confirmed by X-ray structure determination of (L3-NH)Rh(PPh3)2Cl as a representative one. The azoimine chelate ring size of 2 is five membered where the phenyl ring adjacent to the chelate ring is distorted with four longer and two shorter bonds. This structural feature has been attributed to the delocalization of negative charge of the anionic ligands that formed in situ from the precursor (HL-NH2) due to dissociation of an amino proton. The (L-NH)Rh(PPh3)2Cl complexes display an one electron oxidative response in the range of 0.331 to 0.436 V vs. SCE. [Copyright &y& Elsevier]

An alternative way was put forward to separate Ir(IV) and Rh(III) ions from a mixed chloride solution by extraction of rhodium with tri-butyl phosphate (TBP). Stannous chloride was added to the original solution containing RhCl63− and IrCl62− ions before extraction; IrCl62− was reduced to IrCl63−, which cannot be extracted by TBP, and RhCl63− was reduced to Rh(I), which was further complexed with SnCl3−, forming a bi-nuclei bridged complex anions of the form [Rh2Cl6−n(SnCl3)n]4− (n=2–4) and were extracted by TBP simultaneously. A mixed solution of HCl and NaClO3 in which the strong oxidant chlorine was produced, was used for stripping the rhodium. During the stripping process, both Rh(I) and SnCl3− in the complex anions were oxidized to Rh(III) and Sn(IV) destroying the structure of the [Rh2Cl6−n(SnCl3)n]4− (n=2–4) anions; Rh(III) was stripped into the aqueous solution while IrCl62− remained in the organic phase experiencing no change in the strong oxidative environment. Because of their high percent extraction by TBP, the SnCl3− and SnCl62− anions are always kept in the organic phase whether in the process of extraction or stripping the rhodium. The rhodium was selectively stripped with iridium and tin. Finally, all of the tin was stripped by sodium hydroxide and reclaimed, meanwhile, the TBP was regenerated. The effect of Sn/Rh and Sn/Ir molar ratios on the percent extraction was studied. The results show that separation of the two ions can be realized only when the two molar ratios are both at least equal to 4. Two groups of separation tests were conducted: one with the solution containing identical quantities of Rh(III) and Ir(IV), the other with the solution containing very low Rh(III)/Ir(IV) ionic concentration ratio. Both of the separation results proved to be very effective. [Copyright &y& Elsevier]

New In(III), Re(III), Re(V), Pd(II) and Rh(III) Complexes of Toluene-3,4-Dithiol with 2:1 ligand : metal ratio have been prepared and characterized in the solid state. Microanalytical data of the investigated complexes correspond to the general formula [M(TDT)x (H2O)m] where M refers to the metal ion, x, m are the numbers of the coordinated TDT= and H2O respectively. The solid complexes have been characterized using conventional chemical and physical methods of analysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • A cyclometalated Rh(III) complex was synthesized. • It was characterized by CHN analysis, UV–Vis, FT-IR and NMR spectra. • Its molecular structure was confirmed by X-ray crystallography. • The comparison of the experimental and calculated data (DFT) was carried out. • Compound exhibited significant antibacterial activity. • Phosphorescent emissions were observed at 508 and 538 nm in solvent and solid state, respectively. In this work, structural and spectroscopic properties of the cyclometalated Rh(III) complex, [Rh(ppy) 2 (Mdtc)]·H 2 O with ppy = 2-phenylpyridine and Mdtc = morpholine-4-dithiocarbamate were studied by X-ray crystallography and IR, 1H and 13C NMR, electronic absorption and Fluorescence spectroscopy. The title complex crystallized in triclinic, space group P-1 , Z = 2, a = 9.7173(19) Å, b = 11.399(2) Å, c = 12.398(3) Å and α = 107.63(3)˚, β = 100.76 (3)°, γ = 90.84(3)˚. Electronic spectrum of the complex show that ligand-centered (LCT) transitions and ligand-to-metal charge transfer (LMCT). Geometric structure, frontier orbital and electronic absorption spectrum property of the compound were investigated by using density functional theory (DFT) and compared with the experimental data. Calculated geometric parameters agree with the experimental data. Then the agar disc diffusion method was used to determine the antibacterial activity of the ligands and complex on the growth profile of Four Gram-negative bacteria, i.e., Pseudomunas aeroginosa , Salmonella typhai , Proteus mirabilis and Yersinia enterocolitica and two Gram-positive bacteria, i.e., Staphylococcus aureus and Enterococcus faecalis. The activity of the Rh (III) complex against bacteria was considerably stronger than the ligands. [ABSTRACT FROM AUTHOR]

In this work, the aqueous speciation of Rh(III) in chloride medium was investigated by UV-vis spectroscopy for ligand to metal ratios R = (Cl−)/(Rh) ranging from 300 to 5000, at fixed Rh concentration (2.4 × 10−3 M). Under the chemical conditions of this work, no time evolution was observed, which allows for the fitting of the UV-vis data by Principal Component Analysis (PCA) and Multi-Curve Resolution (MCR). From this, and by comparison with literature data, the three independent species [RhCl4]−, [RhCl5]2− and [RhCl6]3− were identified, their individual absorption spectra derived and their respective contribution to the collected experimental UV-vis spectra calculated. Then, extraction of Rh(III) towards the ionic liquid trihexyltetradecylphosphonium chloride was performed. Comparison with the speciation data gives insight into the extraction mechanism and the extracted species. [ABSTRACT FROM AUTHOR]