New Ruthenium Nitrosyl Complexes Combining Potentially Photoactive Nitrosyl Group with the Magnetic Nitroxide Radicals as Ligands.

Two ruthenium nitrosyl complexes of Na[RuNOCl4L] with nitronyl nitroxide radicals coordinated to ruthenium with N-donor pyridine rings were prepared and described. The crystal structure of both complexes is 1D or 2D polymeric, due to the additional coordination of sodium cation by bridging the chloride ligands or oxygen atoms of nitroxides. Partially, the oligomeric forms remain in the solutions of the complexes in acetonitrile. The magnetic measurements in the solid state demonstrate the presence of antiferromagnetic interactions through the exchange channels, with the distance between paramagnetic centers equal to 3.1-3.9 Å. The electrochemical behavior of the prepared complexes was investigated in acetonitrile solutions.

Crystal Structure and Thermal Properties of Double-Complex Salts [M1(NH3)6][M2(C2O4)3] (M1, M2 = Co, Rh) and K3[Rh(NH3)6][Rh(C2O4)3]2∙6H2O.

Here, seven new double-complex salts, [M1(NH3)6][M2(C2O4)3] (M1, M2 = Co, Rh) and K3[Rh(NH3)6][Rh(C2O4)3]2∙6H2O types, are synthesised. The crystal structure and composition of DCS (double-complex salts) are studied by SCXRD, XRD, CHN and IR methods. The complex salts of the [M1(NH3)6][M2(C2O4)3] (M1, M2 = Co, Rh) type can be crystallised both as a crystalline hydrate [M1(NH3)6][M2(C2O4)3]·3H2O (sp. gr. P-3) and as an anhydrous complex (sp. gr. P-1) depending on the synthesis conditions. The process of [Rh(NH3)6][Rh(C2O4)3] formation is significantly dependent on the synthesis temperature. At room temperature, a mixture is formed comprising [Rh(NH3)6][Rh(C2O4)3] and K3[Rh(NH3)6][Rh(C2O4)3]2∙6H2O, while the [Rh(NH3)6][Rh(C2O4)3] target product crystallises at elevated temperatures. The thermal behaviour of double-complex salts is studied by the STA, EGA-MS, IR and XRD methods. The complete decomposition of complex salts in helium and hydrogen atmospheres resulting in metals or CoxRh1-x solid solutions is achieved at temperatures of 320-450 °C.

Pd-Ceria/CNMs Composites as Catalysts for CO and CH4 Oxidation.

The application of composite materials as catalysts for the oxidation of CO and other toxic compounds is a promising approach for air purification. In this work, the composites comprising palladium and ceria components supported on multiwall carbon nanotubes, carbon nanofibers and Sibunit were studied in the reactions of CO and CH4 oxidation. The instrumental methods showed that the defective sites of carbon nanomaterials (CNMs) successfully stabilize the deposited components in a highly-dispersed state: PdO and CeO2 nanoparticles, subnanosized PdOx and PdxCe1-xO2-δ clusters with an amorphous structure, as well as single Pd and Ce atoms, are formed. It was shown that the reactant activation process occurs on palladium species with the participation of oxygen from the ceria lattice. The presence of interblock contacts between PdO and CeO2 nanoparticles has an important effect on oxygen transfer, which consequently affects the catalytic activity. The morphological features of the CNMs, as well as the defect structure, have a strong influence on the particle size and mutual stabilization of the deposited PdO and CeO2 components. The optimal combination of highly dispersed PdOx and PdxCe1-xO2-δ species, as well as PdO nanoparticles in the CNTs-based catalyst, makes it highly effective in both studied oxidation reactions.

Porous Co-Pt Nanoalloys for Production of Carbon Nanofibers and Composites.

The controllable synthesis of carbon nanofibers (CNF) and composites based on CNF (Metals/CNF) is of particular interest. In the present work, the samples of CNF were produced via ethylene decomposition over Co-Pt (0-100 at.% Pt) microdispersed alloys prepared by a reductive thermolysis of multicomponent precursors. XRD analysis showed that the crystal structure of alloys in the composition range of 5-35 at.% Pt corresponds to a fcc lattice based on cobalt (Fm-3m), while the CoPt (50 at.% Pt) and CoPt3 (75 at.% Pt) samples are intermetallics with the structure P4/mmm and Pm-3m, respectively. The microstructure of the alloys is represented by agglomerates of polycrystalline particles (50-150 nm) interconnected by the filaments. The impact of Pt content in the Co1-xPtx samples on their activity in CNF production was revealed. The interaction of alloys with ethylene is accompanied by the generation of active particles on which the growth of nanofibers occurs. Plane Co showed low productivity (~5.5 g/gcat), while Pt itself exhibited no activity at all. The addition of 15-25 at.% Pt to cobalt catalyst leads to an increase in activity by 3-5 times. The maximum yield of CNF reached 40 g/gcat for Co0.75Pt0.25 sample. The local composition of the active alloyed particles and the structural features of CNF were explored.

Pd-Ce-Ox/MWCNTs and Pt-Ce-Ox/MWCNTs Composite Materials: Morphology, Microstructure, and Catalytic Properties.

The composite nanomaterials based on noble metals, reducible oxides, and nanostructured carbon are considered to be perspective catalysts for many useful reactions. In the present work, multi-walled carbon nanotubes (MWCNTs) were used for the preparation of Pd-Ce-Ox/MWCNTs and Pt-Ce-Ox/MWCNTs catalysts comprising the active components (6 wt%Pd, 6 wt%Pt, 20 wt%CeO2) as highly dispersed nanoparticles, clusters, and single atoms. The application of X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) provided analysis of the samples' morphology and structure at the atomic level. For Pd-Ce-Ox/MWCNTs samples, the formation of PdO nanoparticles with an average crystallite size of ~8 nm was shown. Pt-Ce-Ox/MWCNTs catalysts comprised single Pt2+ ions and PtOx clusters less than 1 nm. A comparison of the catalytic properties of the samples showed higher activity of Pd-based catalysts in CO and CH4 oxidation reactions in a low-temperature range (T50 = 100 °C and T50 = 295 °C, respectively). However, oxidative pretreatment of the samples resulted in a remarkable enhancement of CO oxidation activity of Pt-Ce-Ox/MWCNTs catalyst at T < 20 °C (33% of CO conversion at T = 0 °C), while no changes were detected for the Pd-Ce-Ox/MWCNTs sample. The revealed catalytic effect was discussed in terms of the capability of the Pt-Ce-Ox/MWCNTs system to form unique PtOx clusters providing high catalytic activity in low-temperature CO oxidation.

Synthesis and investigation of the thermal properties of [Co(NH3)6][Co(C2O4)3]·3H2O and [Ir(NH3)6][Ir(C2O4)3].

The complexes [Co(NH3)6][Ir(C2O4)3] and [Ir(NH3)6][Co(C2O4)3]·H2O have previously been synthesized and their thermal properties studied. The [Ir(NH3)6][Ir(C2O4)3] and [Co(NH3)6][Co(C2O4)3]·3H2O complexes considered here are the end members in a series of possible isostructural solid solutions based on the complex salts in the Co-Ir system. Their crystal structures and thermal properties are described in detail, including temperature-dependent in situ X-ray diffraction. During the thermolysis of these compounds, layered metal nanoparticles are formed. Close attention is paid to the details of the [Co(NH3)6][Ir(C2O4)3] synthesis. It has been shown that the formation of this complex salt is temperature dependent; upon heating, a new phase of the K3[Co(NH3)6][Ir(C2O4)3]2·6H2O salt is formed, which incorporates the initial iridium compound into the crystal structure of the double complex salt. The target [Co(NH3)6][Ir(C2O4)3] product is obtained if the synthesis is carried out at room temperature.

Formation of Catalytically Active Nanoparticles under Thermolysis of Silver Chloroplatinate(II) and Chloroplatinate(IV).

The thermal behaviour of Ag2[PtCl4] and Ag2[PtCl6] complex salts in inert and reducing atmospheres has been studied. The thermolysis of compounds in a helium atmosphere is shown to occur in two stages. At the first stage, the complexes decompose in the temperature range of 350-500 °C with the formation of platinum and silver chloride and the release of chlorine gas. At the second stage, silver chloride is sublimated in the temperature range of 700-900 °C, while metallic platinum remains in the solid phase. In contrast to the thermolysis of Ag2[PtCl6], the thermal decomposition of Ag2[PtCl4] at 350 °C is accompanied by significant heat release, which is associated with disproportionation of the initial salt to Ag2[PtCl6], silver chloride, and platinum metal. It is confirmed by DSC measurements, DFT calculations of a suggested reaction, and XRD. The thermolysis of Ag2[PtCl4] and Ag2[PtCl6] compounds is shown to occur in a hydrogen atmosphere in two poorly separable steps. The compounds are decomposed within 170-350 °C, and silver and platinum are reduced to a metallic state, while a metastable single-phase solid solution of Ag0.67Pt0.33 is formed. The catalytic activity of the resulting nanoalloy Ag0.67Pt0.33 is studied in the reaction of CO total (TOX) and preferential (PROX) oxidation. Ag0.67Pt0.33 enhanced Pt nano-powder activity in CO TOX, but was not selective in CO PROX.

Revisiting Sodium Hexafluoroiridates: Perspective Precursors for Electronic, Quantum, and Related Materials.

The following salts have been synthesized and structurally characterized: Na2[IrF6]·2H2O (C2/m, a = 6.6327(4), b = 10.0740(6), c = 5.9283(5) Å, ß = 122.3880(10)°) and Na3[IrF6]·2H2O (R-3, a = 7.5963(3), b = 7.5963(3), c = 9.8056(4) Å) (for the first time) by single-crystal X-ray diffraction; the unit cell parameters of a tetragonal phase (P4 2/mnm, a = 5.005(2), c = 10.074(4) Å) of the stable α-Na2[IrF6] were determined for the first time; and the unit cell parameters of ß-Na2[IrF6] (P321, a = 9.332(4), c = 5.136(2) Å) and Na3[IrF6] (P21/n, a = 5.567(4), b = 5.778(4), c = 8.017(2) Å, ß = 90.41(2)°) were determined using powder X-ray diffraction (PXRD). The data of the thermal stability was obtained by differential thermal analysis (DTA) for all substances. The presence of Na3[IrF6]·H2O monohydrate is predicted. H2[IrF6] was prepared in a solution and was demonstrated to behave as a strong dibasic acid.

WSES project on decision support systems based on artificial neural networks in emergency surgery.

The article is a scoping review of the literature on the use of decision support systems based on artificial neural networks in emergency surgery. The authors present modern literature data on the effectiveness of artificial neural networks for predicting, diagnosing and treating abdominal emergency conditions: acute appendicitis, acute pancreatitis, acute cholecystitis, perforated gastric or duodenal ulcer, acute intestinal obstruction, and strangulated hernia. The intelligent systems developed at present allow a surgeon in an emergency setting, not only to check his own diagnostic and prognostic assumptions, but also to use artificial intelligence in complex urgent clinical cases. The authors summarize the main limitations for the implementation of artificial neural networks in surgery and medicine in general. These limitations are the lack of transparency in the decision-making process; insufficient quality educational medical data; lack of qualified personnel; high cost of projects; and the complexity of secure storage of medical information data. The development and implementation of decision support systems based on artificial neural networks is a promising direction for improving the forecasting, diagnosis and treatment of emergency surgical diseases and their complications.

[IGG4-related diseases in endocrinology].

Immunoglobulin-G4-related disease (IgG4-RD) is a chronic immunomediated pathology of different organs of local or systemic nature, which has been established as a separate clinical entity in the early 2000s and is characterized by storiform fibroid inflammation of the affected tissues, their increase, and elevated serum immunoglobulin-G4 (IgG4) levels. The most common manifestations of the disease are major salivary and lacrimal gland enlargement, lymphadenopathy and type 1 autoimmune pancreatitis (AIP1), however, other organs may be also involved (the thyroid, eyes, meninges, heart, lungs, kidneys, aorta, upper airways, mesentery, etc.). The effectiveness of treatment of IgG4-RD, as well as other pathological conditions, is also determined by the timely diagnosis. However, the latter is complicated due to the variety of clinical manifestations and rather variable diagnostic criteria. It is necessary to constantly update the evidence-based knowledge and diagnostic algorithms within this pathology in order to overcome the difficulties, and involve immunologists, endocrinologists, pathologists and specialists in other spheres. This review provides information about the etiology, pathogenesis, and current methods of diagnosis and treatment of IgG4-related diseases, as well as examples of some manifestations of IgG4-RD that an endocrinologist may face in practice.

Preparation of porous Co-Pt alloys for catalytic synthesis of carbon nanofibers.

A simple and convenient procedure for the production of highly dispersed porous Co-Pt alloys to be used as catalysts for the synthesis of nanostructured carbon fibers (CNF) has been developed. The technique is based on the thermal decomposition of specially synthesized multicomponent precursors in a reducing atmosphere. A series of porous single-phase alloys Co-Pt (10-75 at% Pt) have been synthesized. The alloys containing 75 and 50 at% Pt were identified by the x-ray diffraction analysis as the intermetallics CoPt3 and CoPt, respectively. Within the region of 10-35 at% Pt, the synthesized alloys are represented by Co1-x Pt x random solid solutions with face-centered cubic lattice. The alloys obtained are characterized by a porous structure consisting of assembled fragments with a size of 50-150 nm. The obtained alloys were tested in the catalytic chemical vapor deposition of the ethylene to CNF. A significant synergistic effect between Co and Pt in the synthesis of carbon nanomaterials (CNMs) was revealed. The yield of CNF (for 30 min reaction) for catalysts containing 25-35 at% Pt was 30-38 g(CNF)/g(cat), whereas those for Co (100%) and Pt (100%) samples were as low as 5.6 and >0.1 g(CNF)/g(cat), respectively. The produced CNM composed of fibers with a segmented structure was shown to be characterized by a rather high specific surface area (200-250 m2 g-1) and structural homogeneity.

Rh(III) hydroxocomplexes speciation using HPLC-ESI-MS.

A mixture of rhodium(iii) hydroxocomplexes formed during the polycondensation process in alkaline media has been fully characterized by the hyphenated high performance liquid chromatography with electrospray ionization mass spectrometry (HPLC-ESI-MS). The baseline separation was achieved using reverse phase ion-pair chromatography (RP-IP-HPLC) in gradient elution mode. When using SDS as the ion pair, the formation of all types of its associates with the molecules of acetonitrile, as well as oligomers of rhodium aquahydroxocomplexes, etc. was taken into consideration. As a result, it was shown that the test mixture is presented by [Rh(H2O)6]3+, [Rh2(µ-OH)2(H2O)8]4+, [Rh3(µ-OH)4(H2O)10]5+, [Rh4(µ-OH)6(H2O)12]6+.

Insight into the thermal decomposition of ammonium hexahalogenoiridates(IV) and hexachloroiridate(III).

Thermal decomposition of (NH4)3[IrCl6]·H2O, (NH4)2[IrCl6] and (NH4)2[IrBr6] in reductive and inert atmospheres has been investigated in situ using quick-EXAFS and temperature-resolved powder X-ray diffraction. For the first time, (NH4)2[Ir(NH3)Cl5] and (NH4)2[Ir(NH3)Br5] have been proven as intermediates of thermal decomposition of (NH4)3[IrCl6]·H2O, (NH4)2[IrCl6] and (NH4)2[IrBr6]. Thermal degradation of (NH4)2[IrCl6] and (NH4)2[IrBr6] is a more complex process as suggested previously and includes simultaneous formation of (NH4)2[Ir(NH3)Cl5] and (NH4)2[Ir(NH3)Br5] intermediates mixed with metallic iridium. In the inert atmosphere, complexes (NH4)[Ir(NH3)2Cl4] and (NH4)[Ir(NH3)2Br4] as well as [Ir(NH3)3Br3] were proposed as possible intermediates before formation of metallic iridium particles.

Tetraammineplatinum(II) and Tetraamminepalladium(II) Chromates as Precursors of Metal Oxide Catalysts.

[M(NH3 )4 ]A (M=Pt, Pd; A=CrO4 , Cr2 O7 ) and [Pt(NH3 )4 (NO2 )(Cr2 O7 )]NO3 complex salts were synthesized and characterized by a number of physicochemical methods of analysis (IR, single-crystal and powder XRD, and simultaneous thermogravimetry and differential scanning calorimetry with evolved gas analysis mass spectrometry). Thermolysis of the salts obtained in a hydrogen atmosphere proceeds with the partial reduction of chromium to a metallic state and the formation of Mx Cr1-x (M=Pt, Pd) metal solid solution with a chromium content of up to 22 at % and chromium(III) oxide. The thermal decomposition of salts in an inert and oxidizing atmosphere passes through the formation stage of the MCrO2 phase with the delafossite structure followed by its subsequent decomposition into chromium(III) oxide and noble metal. Nanosized Pt-Cr2 O3 and Pd-Cr2 O3 composites obtained by the thermolysis of precursor salts in air at 500 °C and being held at this temperature for 1 h showed a high catalytic activity in the CO total oxidation (TOX) and preferential oxidation in the excess of hydrogen (PROX) processes compared with that of monometallic Pt and Pd powders.

The study of Rh(iii) hydroxocomplexes using capillary zone electrophoresis with a UV-Vis detector: the development of the method.

The expediency of capillary zone electrophoresis application in the study of a mixture of rhodium(iii) hydroxocomplexes is shown for the species formed during the thermal treatment of [Rh(OH)6]3- at 60 °C in alkaline media. As these compounds are unstable in solution because of polycondensation at pH > 10 and the formation of insoluble rhodium(iii) hydroxides at pH 5-10, their acidic derivatives with terminal aqua ligands acted as the objects of the study. Optimal separation conditions were achieved using sodium perchlorate as a background electrolyte, a voltage of +20 kV and pH 2.6. Rhodium(iii) species with different nuclearities were identified in accordance with their UV spectra and the regularities of electrophoretic migration in the capillary. The presence of a dimer was also verified by the spiking of the mixture under investigation with a previously synthesised complex [Rh2(µ-OH)2(H2O)8](NO3)4, which confirms the correct identification.

Spectroscopic and DFT Study of RhIII Chloro Complex Transformation in Alkaline Solutions.

The hydrolysis of [RhCl6]3- in NaOH-water solutions was studied by spectrophotometric methods. The reaction proceeds via successive substitution of chloride with hydroxide to quantitatively form [Rh(OH)6]3-. Ligand substitution kinetics was studied in an aqueous 0.434-1.085 M NaOH matrix in the temperature range 5.5-15.3 °C. Transformation of [RhCl6]3- into [RhCl5(OH)]3- was found to be the rate-determining step with activation parameters of ΔH† = 105 ± 4 kJ mol-1 and ΔS†= 59 ± 10 J K-1 mol-1. The coordinated hydroxo ligand(s) induces rapid ligand substitution to form [Rh(OH)6]3-. By simulating ligand substitution as a dissociative mechanism, using density functional theory (DFT), we can now explain the relatively fast and slow kinetics of chloride substitution in basic and acidic matrices, respectively. Moreover, the DFT calculated activation energies corroborated experimental data that the kinetic stereochemical sequence of [RhCl6]3- hydrolysis in an acidic solution proceeds as [RhCl6]3- → [RhCl5(H2O)]2- → cis-[RhCl4(H2O)2]-. However, DFT calculations predict in a basic solution the trans route of substitution [RhCl6]3- → [RhCl5(OH)]3- → trans-[RhCl4(OH)2]3- is kinetically favored.

Successful synthesis and thermal stability of immiscible metal Au-Rh, Au-Ir andAu-Ir-Rh nanoalloys.

We successfully prepared face-centred cubic nanoalloys in systems of Au-Ir, Au-Rh and Au-Ir-Rh, with large bulk miscibility gaps, in one-run reactions under thermal decomposition of specially synthesised single-source precursors, namely, [AuEn2][Ir(NO2)6], [AuEn2][Ir(NO2)6] х [Rh(NO2)6]1-х and [AuEn2][Rh(NO2)6]. The precursors employed contain all desired metals 'mixed' at the atomic level, thus providing significant advantages for obtaining alloys. The observations using high-resolution transmission electron microscopy show that the nanoalloy structures are composed of well-dispersed aggregates of crystalline domains with a mean size of 5 ± 3 nm. Еnergy dispersive x-ray spectroscopy and x-ray powder diffraction (XRD) measurements confirm the formation of AuIr, AuRh, AuIr0.75Rh0.25, AuIr0.50Rh0.50 and AuIr0.25Rh0.75 metastable solid solutions. In situ high-temperature synchrotron XRD (HTXRD) was used to study the formation mechanism of nanoalloys. The observed transformations are described by the 'conversion chemistry' mechanism characterised by the primary development of particles comprising atoms of only one type, followed by a chemical reaction resulting in the final formation of a nanoalloy. The obtained metastable nanoalloys exhibit essential thermal stability. Exposure to 180 °C for 30 h does not cause any dealloying process.

Polynuclear Hydroxido-Bridged Complexes of Platinum(IV) with Terminal Nitrato Ligands.

For the first time the polynuclear hydroxido-bridged platinum(IV) nitrato complexes with nuclearity higher than two were isolated from nitric acid solutions of [Pt(H2O)2(OH)4] and crystallized as supramolecular compounds of macrocyclic cavitands cucurbit[n]uril (CB[n], n = 6,8) and 18-crown-6 ether: [Pt4(µ3-OH)2(µ2-OH)4(NO3)10]·CB[6]·25H2O (I), [Pt6(µ3-OH)4(µ2-OH)6(NO3)12](NO3)2·CB[8]·50H2O (II), and [H3O⊂18-crown-6]2[Pt2(µ2-OH)2(NO3)8][Pt4(µ3-OH)2(µ2-OH)4(NO3)10] (III). The isolation of the compounds in the single crystalline state allows the determination of the structure of the tetranuclear and hexanuclear complexes [Pt4(µ3-OH)2(µ2-OH)4(NO3)10] and [Pt6(µ3-OH)4(µ2-OH)6(NO3)12](2+), which have been previously unknown in the solid state. Stability of Ptx(OH)y cores of the polynuclear nitrato complexes toward alkaline hydrolysis was verified by (195)Pt NMR spectroscopy. Analysis of (195)Pt NMR spectra of the compound III reveals that addition of every Pt(µ-OH)2Pt ring results in ∼260 ppm downfield shift relative to the mononuclear form, which allows the prediction of signal positions for complexes of higher nuclearity.

Speciation of platinum(IV) in nitric acid solutions.

The speciation of platinum(IV) ions in nitric acid (6-15.8 M) solutions of H2[Pt(OH)6] has been studied by (195)Pt NMR and Raman spectroscopy. Series of aqua-hydroxo-nitrato complexes [Pt(L)(x)(NO3)(6-x)] (L = H2O or OH(-); x = 0, ..., 6) were found to exist in such solutions. The pair additivity model of chemical shifts and statistical theory were used to assign signals in NMR spectra to particular [Pt(L)(x)(NO3)(6-x)] species. Mononuclear hexanitratoplatinates(IV) have been isolated in solid state in substantial yield as pyridinium salt (PyH)2[Pt(NO3)6] and characterized by single-crystal X-ray diffraction. Aging of the platinum nitric acid solutions for more than 5-6 h results in oligomerization of [Pt(L)(x)(NO3)(6-x)] species and the formation of oligonuclear aqua-hydroxo-nitrato complexes with OH(-) and NO3(-) bridging ligands. Oligomeric platinum(IV) complexes with two and four nuclei were unambiguously detected by NMR on (195)Pt -enriched samples. Oligomers with even higher nuclearity were also detected. Dimeric anions [Pt2(µ-OH)2(NO3)8](2-) have been isolated as single crystals of tetramethylammonium salt and characterized by X-ray diffraction.