A comparison was made between the separate extraction and coextraction of neodymium and palladium from nitric acid solutions with bifunctional phosphorylated thiacalix[4]arene (TCPO) and monofunctional extractants that modeled it—phosphorylated calixarene (CPO), thiacalixarene (TCA), and their mixtures—for evaluating the mutual influence of S- and PO-donor sites of the extractants. A decrease in DNd was detected only for TCPO: it was less that 0.1 as against 1.6 for CPO. 31P{1H} and 13C{1H} NMR spectroscopy studies showed that the decrease in the neodymium extraction with TCPO is similar to the inhibition of the catalytic activity of enzymes (TCPO analogs) in the presence of effectors (analogs of rare-earth elements) in phosphorylation—dephosphorylation processes. Their coordination to the allosteric CH2P(O)R2 site leads to high chemical shift (4 ppm) of the signal of the 13CH2 spacer and to the formation of TCPO hydrolysis products (n-methylthiacalix[4]arene and, probably, dibutylhydroxophosphinate). The results of the extraction with TCA–CPO mixtures are of interest for a simplified process (PUREX) and a process being developed (CARBEX) as applied to the corecovery of neodymium and palladium from nitric acid solutions and their separation from carbonate solutions after neodymium stripping.

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.

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).

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.

The extractability of palladium nitro complexes with the charge state of sulfur and oxygen atoms in thiacalix[4]arenas in the cone and 1,3-alternate conformations are compared. The results of X-ray photoelectron and X-ray emission studies indicate the presence of considerable electron density on the bridging sulfur atoms, which is due to the contribution of the sulfur 3p AO to the upper occupied MOs of molecules. A series of changes in the electron density on sulfur atoms in the order calixarene thioethers > thiacalixarenes > dialkylsulfides ((C(10)H(21))(2)S) > (C(6)H(5))(2)S not completely coincide with changes in their extrability, which can be caused by different nature and stoichiometry of the formed palladium complexes.

Calix[n]arenes (n = 4, 6) existing in the cone, 1,3-alternate or 1,3,5-alternate conformations and functionalized by two, four or six Bu2P(O)CH2O groups have been synthesized by the alkylation of hydroxycalix[4,6]arenes with tosylate of dibutylhydroxymethylphosphine oxide. Their molecular and crystal structures as well as binding properties towards of heterometallic Ru/Zn complexes were investigated. Due to the "calixarene effect" the phosphine oxides are effective extractants for the Ru/Zn complexes.

The extraction of non-ferrous metal (M2+) nitrates by the calix[4,6]arenes (L), bearing four or six phosphine oxide donor groups at the upper or at the lower rim, was quantitatively described in the form of [M-n(NO3)(2n)L] (n = 1, 2) complexes. The extraction constants (Zn2+ > Cu2+ > Co2+ > Ni2+) for the both types of L coincide with Irving-Williams sequence. Calix[4]arenes, phosphorylated at the lower (narrow) rim, provide better stability of ML complexes because of the best spatial fitting of M2+ by the donor groups. For the upper (wide) rim phosphorylated calix[4]arenes M2L and ML2 complexes are more stable. Unusual zwitterionic [Co-2(NO3)(4)L] complex of the lower rim tetraphosphorylated calix[4]arene 1 was determined by X-ray structural analysis.

Synergetic extraction of [RuNO(NO 2 ) 4 OH] 2− by calix[4]arene phosphine oxides (L) in the form of Ru/M heterometallic complexes was studied in the presence of nonprecious metals (M 2+ ). The main extraction laws were recognized for [M(NO 3 ) 2 L n ] and [RuNO(NO 2 ) 4 OH])ML m ], where M 2+ = Zn 2+ , Cu 2+ , Co 2+ , or Ni 2+ and n , m = 1 or 2; extraction constants were determined for these metals. The variation row of the extraction constants with varying metal (Zn 2+ > Cu 2+ > Co 2+ > Ni 2+ ) coincides with the Irving-Williams row. Two or three PO groups of extractant L and the OH and NO 2 groups of the ruthenium anion are coordinated to the M 2+ atom in Ru/M complexes. The conditions for generation of the Ru/Zn complex and its complete extraction were optimized as applied to the extraction of fission ruthenium from nitrated nitric acid and imitation solutions.

New calix[n]arenes (n = 4, 6) grafted with different phosphine oxide metallocomplexing groups were synthesized and examined as extractants of the heterometallic Ru/Zn complexes. The calixarene macrocyclic effect and the Ru/Zn synergism in the extraction process were investigated. Size and conformation of the calixarene platform as well as electronic nature of substituents at phosphorus atom influence the extraction.

The synergistic extraction of [RuNO(NO 2 ) 4 OH] 2− by diphenyl(dibutylcarbamoylmethyl)phosphine oxide (L) in the presence of nonprecious metal cations (M 2+ ) is studied; the extraction occurs on the account of the formation of heterometal complexes [RuNO(NO 2 ) 4 OHML m ] (M = Zn, Cu, Co, Ni) due to the addition of M 2+ to ruthenium through the oxygen atoms of the OH and NO 2 groups and the bidentate coordination of L to M 2+ . The extraction constants for Ru/M complexes and ML n (NO 3 ) 2 are determined. The variation in the extraction constants with changing M (Co, Zn, Cu > Ni) does not agree with the Irwing-Williams row, unlike the extraction with monodentate PO-containing extractants (Zn > Cu > Co > Ni). The feasibility of ruthenium extraction in the form of Ru/M complexes from complex nitrate-nitrite solutions is demonstrated.

Structural models have been proposed for heterometallic complexes that can be formed in extracts containing Ru anions and M cations (M=Cu, Zn, Co or Ni). Formation of these complexes is accompanied by Ru–O distance increase while the Ru–N distances are unchanged within the determination error. Clearly defined experimental maximum in the curves of 3d metals radial distribution functions gives an indication of Ru atom existence at the rigidly fixed distance and makes direct evidence of a rigid chemical bond between Ru- and M-containing fragments of the heterometallic complex. The obtained data indicate that double coordination of solvated 3d metals cations to the ruthenium complex could take place via the oxygen atom of the hydroxyl group and the NO fragment of the nitro group both linked to the ruthenium atom.