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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]

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]

[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]