Comparison of extraction properties of macrocyclic calix[4,6]arenethiaethers (CATE) with their acyclic analogs R 2 S (R = C 6 H 13 , C 8 H 17 ) for the recovery of [Rh(NO 2 ) 3 (H 2 O) 3 ] 0 rhodium form from nitric acid solutions was carried out. Rhodium recovery with CATE (0.05 M) in the absence of accelerating additives under optimal conditions exceeds 90% at 5–10-fold preconcentration and is only 1–3% for R 2 S (1 M). Extraction kinetics was studied and hypothesis on the mechanism of multiple acceleration of rhodium recovery was proposed for CATE extraction, the mechanism includes the formation of intermediate product of colloidal- chemical nature on account of the surface activity of the macrocycle and its reaction with rhodium accompanied by rhodium chelation to the sulfur atoms of neighboring fragments of the macrocycle. The obtained results are of interest for the development of methods for the isolation of fission rhodium from nitrate–nitrite nitric acid solutions.

Проведено количественное сопоставление экстракции палладия и серебра n-трет.-бутил-тиакаликс[4]ареном (ТКА) из азотнокислых, карбонатных, аммиачно-карбонатных и аммиачных растворов. Показано, что в оптимальных условиях ТКА может быть использован для совместного извлечения палладия и серебра из карбонатных систем карбэкс-процесса, селективного извлечения палладия в азотнокислых растворах и селективного извлечения серебра в аммиачно-карбонатных растворах. Коэффициенты распределения металлов и эффективные константы экстракции уменьшаются с ростом комплексообразующих свойств водной фазы (Na2CO3 > NH4HCO3). В случае серебра определяющим фактором является аммиачная закомплексованность катиона Ag+, для палладия определенную роль играет также рН растворов за счет образования гидроксокомплексов.

A quantitative comparison of palladium and silver extraction with p-tert-butylthiacalix[4]arene (TCA) from nitric acid, carbonate, ammonia-carbonate, and ammonia solutions was carried out. It was shown that TCA under optimal conditions can be used for concurrent extraction of palladium and silver from carbonate systems of CARBEX process, selective recovery of palladium from nitric acid solutions, and selective silver extraction from ammonia-carbonate solutions. Metal distribution ratios and effective extraction constants decrease when the complex-forming ability of aqueous phase rises (Na2CO3 > NH4HCO3). The ammonia complexation of Ag+ is determining factor for silver, solution pH plays a certain role for palladium due to formation of hydroxo complexes.

Показано, что основные закономерности экстракционного извлечения рутения нейтральными фосфорорганическими соединениями (L) в виде гетерометаллических комплексов [RuNO(NO2)4MLn] (M = Zn, Cu, Co, Ni; n = 2–3) сохраняются при переходе к сорбционному извлечению импрегнированными L сорбентами. Сорбент на основе разнорадикального фосфиноксида может быть использован для хроматографического выделения рутения, при этом степень сквозного извлечения рутения на стадиях сорбции–десорбции (90–94%) сохраняется после семи циклов.

It is shown that the main features of ruthenium extractive recovery with neutral organophosphorus compounds (L) as [RuNO(NO2)4ML n ] (M = Zn, Cu, Co, Ni; n = 2–3) heterometallic complexes are retained on the sorption recovery with sorbents impregnated with L. The sorbent based on mixed trialkylphosphine oxide can be used for the chromatographic recovery of ruthenium, the extent of total ruthenium recovery at sorption-desorption stages (90–94%) retains after seven cycles.

A comparison was made for extraction systems based on the mixtures of calix[ n ]arenes phosphorylated at the upper and lower rims (PCA, n = 4 and 6) with dioctyl sulfide (DOS) for recovery of rhodium in the form of [Rh(H 2 O) 3 (NO 2 ) 3 ] 0 from acid nitrate-nitrite media. Because of inertness of rhodium compounds, the main attention was devoted to extraction kinetics. The kinetic efficiency of DOS + PCA systems was found to be much higher than that for DOS alone, whereas the components of the mixtures do not extract rhodium. Alkyl(ethyl)calixphosphine oxides are the most promising, they behave as accelerating additives in extractant mixtures. Extraction kinetics of [Rh(H 2 O) 3 (NO 2 ) 3 ] 0 species was studied and extraction systems were selected to develop method for the recovery of fission rhodium.

The state of ruthenium in conjugated phases upon extraction of trans-[Ru(15NO)(15NO2)4(OH)]2− complex with tri-n-octylphosphine oxide (TOPO) in the presence of Zn2+ and subsequent back extraction with H15NO3 and NH3(concd.) solutions was studied by 15N NMR. Binuclear complexes [Ru(NO)(NO2)5−n (μ-NO2) n−1(μ-OH)Zn(TOPO) n ] and [Ru(NO)(NO2)4−n (ONO)(μ-NO2) n−1(μ-OH)Zn(TOPO) n ], where n = 2, 3, are predominant forms in extract. Kinetic restrictions for ruthenium extraction with TOPO solution in hexane and its back extraction with aqueous solutions of nitric acid and ammonia are eliminated in the absence of direct coordination of extractant to ruthenium. fac-Dinitronitrosyl forms [Ru(NO)(H2O)3(NO2)2]+, [Ru(NO)(H2O)2(NO2)2(NO3)]0 (3 and 6 M HNO3) and [Ru(NO)(H2O)(NO2)2(NO3)2]− (6 M HNO3) prevail in nitric acid back extracts. Equilibrium constant at ambient temperature (0.05 ± 0.01) was assessed for the coordination of second nitrate ion to nitrosylruthenium dinitronitrato complex. Complex species [Ru(NO)(NO2)4(OH)]2− and [Ru(NO)(NO2)3(ONO)(OH)]2− prevail in ammonia back extract.

p-tert-Butylcalix[4]arene was compared with its acyclic analogs in palladium extraction from nitric acid solutions as mononuclear and poly(bi)nuclear complexes with participation of protonated molecules of podands and macrocycle. The extraction ability of podands is similar to that of macrocycle because of the same character of complexation (Pd: S = 1: 1) without formation of new chelates and lower than that of monodentate analog owing to formation of a square complex (Pd: S = 1: 2).

Methods for preparing gold nanoparticles (NPs) surface-stabilized with di-(2-ethylhexyl)dithiophosphoric acid (DTPA) and tris(2-aminoethyl)amine (TAEA), which endow the nanoparticles with hydrophobic and hydrophilic properties, are described. In the case of DTPA, Au-NPs are first synthesized with surfactant shells by means of reducing [AuCl 4 ] − with hydrazine in inverted micelles of oxyethylated Triton N-42 in a low-polarity medium of decane; then, the micelles are destroyed by polar chloroform in the presence of DTPA, which has a great affinity to gold due to its sulfur donor atoms and substitutes for the surfactant on the surface of the nanoparticles. In preparing hydrophilic nanoparticles, [AuCl 4 ] − is reduced with solid NaBH 4 directly in a nonaqueous solution of TAEA based on an ethanol and 2-propanol (3: 10) mixture. The nanoparticles are characterized by elemental analysis (for Au, C, H, N, and Na), X-ray powder diffraction, electronic absorption spectra, IR spectra, photon-correlation spectra, and transmission electron microscopy (TEM).

Calix[4]arene 1, thiacalix[4]arenes 2(LH4), and calix[4]arenethioether 3 were compared in palladium extraction from nitric acid solutions; D Pd for 2 was shown to be 2–3 orders of magnitude larger than for 1 at pH > 3 (comparable with 3) because of cation-exchange and coordination extraction of palladium. It was shown by extraction methods and IR spectroscopy that thiacalixarenes 2 extract complex species [Pd n L m H4 − 2n ] (m = 1, n = 1 and 2) and [(PdA2) n L m H4] (A = m = 1, n = 1–4) from nitric acid solutions at pH 3. Extraction constants for these palladium species that satisfactorily describe experimental data were calculated. As distinct from 3, thiacalixarenes 2 are promising for the combined extraction of palladium and silver from alkaline solutions and the selective extraction of fission palladium from nitric acid solutions. Phosphorylated at the upper rim thiacalixarenes 2 can be considered as bifunctional extractants for the separation of fission radionuclides.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

In continuation of our studies on the extraction of rhodium from acid nitrate-nitrite aqueous solutions with a mixture of alkylanilinium nitrate and dialkyl sulfide, a back-extraction of rhodium was studied. Thiourea (TU) is an efficient agent for the back-extraction of rhodium and concomitant noble metals (Pd, Ru, Ag). The back-extraction of rhodium proceeds via coordination mechanism, [Rh(tu)6](NO3)3 being the major product. Aqueous 1 mol/L solution of TU ensures stripping of at least 91% rhodium and provides its relative concentrating up to 4 times (time of phase contact is 5 min, temperature 20–35°C). The presence of palladium and other noble metals in extract does not affect the Rh stripping.

Extraction of platinum group metals and gold from hydrochloric acid solutions with calix[4]arenamines (CAA) and calix[ n ]arene thioethers ( n = 4, 6; CTE) was studied. The high macrocyclic effects (10 2 –10 3 ) are due to chelation between metals and the donor centers of macrocycles in the systems CAA-Pd and CTE-Ag, Pt II , and Pt IV . New CAA-based extracting systems for collective extraction of Pd, Pt, Au, Ir, and Rh and new CTE-based systems for separation of Au and Pd from Ag and Pt were justified.

Compared were dialkylcalix[4]phosphine oxides (L) having PO groups in the opposing rims as regards the extraction of [RuNO(NO 2 ) 4 (OH)] 2− , nonprecious metals (M 2+ ), and Ru/M heterometallic complexes of their base. The extraction constants for the ion association {(Na + ) 2 (LH 2 O) r [RuNO(NO 2 ) 4 (OH)] 2− and the degree of aggregation of L were calculated. The destruction of (LH 2 O) r upon metal extraction was verified IR-spectroscopically. The stoichiometry was determined and extraction constants were calculated for mono- and binuclear complexes [M m L n (NO 3 ) 2 m ] and mononuclear Ru/M species [RuNO(NO 2 ) 4 (OH)ML n ]. Nonprecious metals form mononuclear ML complexes in the lower rim. The size of the upper rim is responsible for the addition of a second metal nitrate molecule or addition to L or the addition of a second L molecule to the metal. Ru/M complexes with all L are present in an organic phase as two mononuclear species, ML and ML 2 . Rationale is given to the selection of extraction systems for recovery of ruthenium from nitrated nitric acid solutions selectively or together with actinides and lanthanides in the form of Ru/M complexes.