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New cyclometalated neutral iridium(III) complexes [Ir(L)2(dbm)] have been synthesized, where L is 2-arylphenanthroimidazoles with various electron-donor or acceptor substituents, dbm is dibenzoyl-methane. The compositions and structures of the ligands and complexes have been studied by X-ray diffraction and high-resolution mass spectrometry. In the absorption spectra of the complexes, a bathochromic shift of the absorption maxima is observed with an increase in the electron donor properties of the ligands. All the complexes show the reversible redox behavior; redox potentials fall in the range of 0.8–1.6 V. The combination of the obtained results allows us to consider the synthesized compounds as potential photosensitizers in solar cells.

New cluster complexes of lanthanides(III) and nickel(II) [Ln{Ni(Gly)2}6]3+[Ln(NO3)6]3– have been synthesized, where Ln = La (I), Ce (II), and Pr (III); and Gly is glycinate. The structures of compounds I–III are determined by X-ray diffraction. The icosahedral cavity in the complex cation, where the lanthanide ion resides, has a fixed size independent of the nature of the central Ln(III) ion. In the complex anion, on the contrary, the Ln–O distances naturally decrease from La(III) to Pr(III). The optical properties of cationanion complexes I–III are studied. Based on the assignment in the electronic absorption spectra of the complexes, it is shown that the absorption bands are caused by d–d electronic transitions.

A new cyclometalated iridium(III) complex [Ir(L)2(Hdcbpy)] (1) has been synthesized, where L is 1-benzyl-2-phenylbenzimidazole and Hdcbpy is monoprotonated 4,4′-dicarboxy-2,2′-bipyridine. The structure of complex 1 has been determined by X-ray diffraction. The optical properties of complex 1 have been studied, and the quantum yield of luminescence has been measured.

A series of mixed-ligand cyclometalated iridium(III) complexes with 2-aryl-1-phenylbenzimidazoles (where aryl is phenyl, 4-chlorophenyl, 4-(N,N-dimethylamino)phenyl, 3,4-dimethoxyphenyl, and 2-thienyl) and 11-carboxydipyrido[3,2-a:2′,3′-c]phenazine have been synthesized and characterized by 1H NMR and 31P NMR spectroscopy and mass spectrometry. The electron absorption spectra (EASs) of the complexes are observed to contain charge-transfer bands in the low-energy region (below 600 nm, ɛ ≈ (1–3) × 103 mol/(L cm)). The bands experience appreciable bathochromic shifts as the electron-donating properties of a benzimidazole ligand strengthen. The complexes manifest luminescence in the yellow-red spectral region. According to alternating current voltammetry data, reversible and quasi-reversible redox transitions (E ox ≈ 1.2–1.7 V with respect to SHE, CH3CN) are observed in solutions of the studied complexes.

The existence of Pu(VIII) was shown in alkaline solutions and in nonpolar solvents (CCl4 and CHCl3) on the ground of such experimental facts like extraction of plutonium species, obtained by means of ozonization of Pu(VI) alkaline solutions into CCl4 and CHCl3; volatility of Pu compounds out of aqueous alkaline solutions, and the mentioned solvents. The product of interaction between PuO3 · 0.8H2O and XeF2 in CCl4 and CHCl3 was of the same chemical form for both cases and identical with the form of the product of volatility of Pu out of these organic solutions. The electronic absorbance spectra of these products in CCl4 and CHCl3 were fairly similar to the ones for OsO4 and RuO4. The band of absorption in these spectra with the maximum at 332 nm corresponds to the charge transfer of metal-ligand type [π(O)→Pu], as the value of molar extinction coefficient ε was found to be higher than 2 · 103 L/mole cm. A satisfactory agreement between the energies for the transitions of PuO4 molecule designed by X α -SW method and experimental data was observed. A similar accordance was observed for the designed vibration frequency (DFT-method) with the one found as result of analysis of the vibration structure of the experimental spectra.

The Am volatility from 4 M NaOH solutions in the course of their ozonation at 80°C was studied. The formation of volatile Am compounds under these conditions was proved by α-ray spectrometry. The whole set of data on the volatility and kinetics of reduction of ozonized Am solutions suggest possible formation of short-lived hydroxo complexes of Am in higher oxidation state, including Am(VIII), along with Am(VI) hydroxo complexes, with AmO4 possibly existing in equilibrium with these Am(VIII) species. No Cm volatility was detected under the same conditions. The observed differences in the behavior of Pu and Am, on the one hand, and Np and Cm, on the other hand, under identical ozonation conditions are attributed to the ability of Pu and Am to be oxidized under these conditions to unstable octavalent state, responsible for their volatility.

Processes that occur in strong alkaline solutions of iridium(III) and iridium(IV) hydroxo complexes have been studied by EPR and electronic absorption spectroscopy. It has been demonstrated that dissolution of iridium compounds in alkaline solutions should be accompanied by a series of complicated transformations involving oxygen, which lead to the formation of several binuclear iridium(III, III), (III, IV), and (IV, IV) dioxygen complexes.

A complex of 57Fe with 5-{4-[((4′-hydroxybenzo-15-crown-5)-5′-yl)diazo]phenyl}-10,15,20-triphenylporphyrin was studied by Mossbauer spectroscopy. The presence of signals of two types in the spectra (a doublet and an extended absorption band over a wide velocity range) suggests that the Fe atoms occupy two structurally different positions in this complex. The dependences of the doublet asymmetry on temperature and the angle between the normal to the sample plane and the γ-ray beam were studied. The isomer shift δ of the doublet in the temperature range from 360 to 5 K changes from 0.25 to 0.41 mm/s, while the quadrupole splitting remains virtually unchanged (Δ ≈ 0.65 mm/s). The relaxation-type absorption over a wide velocity range, the relative area of which strongly varies with temperature, can be described by a broad singlet with the following parameters: δ = 0.30–0.44 mm/s and Γ = 2.8–3.38 mm/s. According to the δ values, both signals are due to Fe(III) derivatives.

Stabilization of 57Fe compounds in matrices of solid solutions of platinum(IV) superoxo- and hydroxo complexes was probed by Mossbauer spectroscopy. The ratio FeIII/FeIV in these matrices is 20/1.

The thermodynamics of the matrix stabilization effect is considered using the concept of isomorphous miscibility. The influence of defects and nonequilibrium on the matrix stabilization is discussed. The existing thermodynamic interpretation of the nature of the matrix stabilization effect is demonstrated not to be perfect.

The state of the art of the problem of matrix stabilization of transition metal ions in unstable oxidation states is surveyed. Basic aspects of the problem concerning the genealogy of matrix systems suitable for the stabilization of this property are classified. Appropriate examples are given, and the data that do not fit the suggested scheme are discussed. This is the case, in particular, for cluster systems stabilized in frozen aqueous solutions, as well as for clusters formed under simpler conditions. The problem of identification of oxidation states in matrix systems, as well as the types of matrices suitable for the stabilization of unstable oxidation states and methods of their stabilization in matrix systems, is considered.

A comparative analysis of dark conductivity and photoconductivity of cobalt(II) etioporphyrin, Co(II)EP, thin films in the presence of various gases was performed. The major contribution to conductivity of both types was made by oxygen molecules adsorbed on the surface of the gas sensitive layer. The concentration of adsorbed oxygen molecules increased under light action on the surface of films, which increased film conductivity at the given temperature. Light action could be used to reach maximum sensor sensitivity of Co(II)EP films toward ammonia at room temperature.

The structural and spectral data on Pt(OH)6nclusters (n = −2, −1, 0) obtained by ab initio methods have been considered. The data for n = −2 are in good agreement with the published data on hexahydroxoplatinates(IV).

Stabilization of oxidation states (OSs) for transition elements is considered. Distinctions between methods for stabilizing OSs in compounds in solution and in a solid state are discussed. The factors influencing stabilization are elucidated. Generation of high OSs of metals in alkali solutions is noticed. The specifics of stabilization of high OSs in solid compounds, including those in which mixed-valence effects are observed, and in solid matrix systems, in particular, in perovskite-related ones, are discussed. New data are cited concerning the stabilization of metal OSs in trans-dioxo complexes [MO2L4] 2 , where M = Mo, Tc, Ru, W, Re, or Os; and in the paramagnetic clusters that were discovered in neutral tungstates and hydroxo complexes of Rh, Ir, Pt, Pu, or Fe, and other elements in unusual high OSs.

The comparative stability of oxohydroxoruthenium(VI) and oxohydroxoosmium(VI) anions with different coordination numbers has been calculated by the relativistic density functional theory method with inclusion of spin-orbit coupling. In line with experimental data, the computations point to the stability of the ruthenium complex RuO3(OH) 2 2− − with CN = 5, whereas osmium is stabilized in a six-coordinate environment (OsO2(OH) 4 2− ). The spin state of the stable Ru complex is close to triplet and that of the Os complex, to singlet.

69 Processes involving the transition of chemical compounds into the gas phase are of both theoretical and practical significance. Such processes are impor� tant for actinides because their concentration, isola� tion, and purification and also isotope separation are known to present serious difficulties. Such processes are also important for plutonium. Assuming that the properties of the previously described plutonium tetroxide [1, 2] can be analogous to those of easily sub� limable osmium and ruthenium tetroxides and taking into account that both RuO 4 and OsO 4 can sublime even on weak heating from alkaline media, we tested the hypothesis of PuO4 volatility from alkaline solu� tions containing Pu(VIII). The existence of Pu(VIII) complexes (although of unknown composition) in a mixture with Pu(VII) complexes was postulated for the first time in [3–6], where it was assumed that Pu(VIII) derivatives can form under the action of an ozone–oxygen mixture on alkaline solutions of Pu(VI) complexes. This is also indicated by the corresponding spectral characteristics of Pu(VIII) and Pu(VII) complexes [7]. The extrac� tion of presumably PuO4 [1] from ozonated solutions suggests that they are characterized by a complex sys� tem of equilibria and contain both Pu(VII) and Pu(VIII) complexes and the said binary oxide. Thus, in an alkaline solution, there is likely a complex–tet� raoxide dynamic equilibrium, which can shift under the action of suitable extractants [1] and, furthermore, on heating. A similar equilibrium can also be assumed

A hypothesis of the ligand matrix stabilization of metal ions in high oxidation states is considered using the structural thermodynamic model and stabilization of Zr4+ ion in ZrC60 cluster as an example. The corresponding energy estimates are presented for fullerides of the M z @C m M s type (m ≥ 60). The possibility of using fullerenes as matrices with a high electron affinity is shown.

Sodium ferrates(IV) and (VI) were synthesized by the reaction between Fe2O3 and Na2O2 in a dry oxygen stream. The Mossbauer data for the obtained samples are presented (for Na2FeO3−δ=0.18(2) mm/s; for Na4FeO5−δ=−0.54(2) mm/s). It was shown that pure K2FeO4 and Cs2FeO4 can be obtained by heating Fe2O3 with apropriate alkali metal peroxides.

Alkaline solutions of iron compounds synthesized by anodic dissolution of metallic iron in NaOH media have been studied by Mossbauer spectroscopy. The values of the isomer shift on iron in higher oxidation states are presented. The formation of the peroxoderivatives of iron in the solutions were not fixed.

In order to improve AV construction, it is necessary to solve a series of bioengineering problems, including the optimization of AV geometry and the selection of artificial heart valve (AHV) orientation in the AV. Toward this goal, a series of studies were conducted concerning flow structure in model AVs, covering among other things, planar models [6], glass models [5], a specially prepared AV (optical knife method) [3], during orientation of an AHV disk on the AV membrane (optical polarization method) [6], and on AV output [2]. From the viewpoint of the authors, practical interest has focused on the investigation of flow structure throughout the volume of actually utilized AVs [4] with a series of AHVs in order to provide fabrication recommendations leading to the improvement of existing and workable AV and AH constructions. Visualization studies of flow structure were carried out using the laser knife method. The principle of this method consists of the following. A light beam is formed by a lens system, a mirror and slitted diaphragm into a fine beam and then guided into the cross section of the model to be investigated. A solution is introduced into the fluid flow having fluorescent properties such that the maximum fluorescent radiation lies in a longer wavelength region than the maximum spectral light intensity. The molecules of the fluorescent substance, when the pencil of light rays strike the flowing fluid, initiate light emission of a characteristic fluorescent wave length. Since the characteristic time for the process of light absorption, molecular excitation, and radiation (fluorescence) is short, usually 10 -~ to 10 -s sec, the resulting pictures portray the instantaneous distribution of the fluorescent substance in the complete stream. It should be pointed out that the presented kinogram shows the instantaneous distribution of the fluorescent substance in a section not a projection, as would be the case when using a dye solution. A schematic diagram of the experimental setup is presented in Fig. i. The AV 1 and AHVs 2 were placed in a rectangular-shaped vessel 3 filled with water. Water was utilized as the working fluid. Fluid was supplied to the AV from an upper supply tank 4 and ran off into a lower tank 5. Illustrated in Fig. 2 is the variant 1 orientation in the AV of the EMIKS type AHV disks, where the right valve is the input and the left is the output. Flow visualization was carried out at sections A--A and B--B. Visualization was conducted under stationary flow conditions with two different values for the flow rate: gl = 0.6

We have considered the thermodynamic bases for the application of heat engines to drive the ventricles of artificial hearts in humans. An analysis of the Carnot, Brighton, Stirling, and Rankine cycles indicated that the Rankine cycle is preferable, specifically in its implementation in the steam piston engine. In this context it is essential that the optimal operating frequency for the motion of the steam engine's piston lies in the range of physiological frequencies for the contraction of the human heart, which allows the application of this engine for driving IAH ventricles without converting frequencies.

1. According to thermogravimetric data, PrF4, decomposes when heated, with evolution of fluorine, as in the case of CeF4 and TbF4. 2. The authors have measured the vapor pressure of the fluorine formed by thermolysis of rare-earth tetrafluorides, and have calculated the thermodynamic characteristics of these tetrafluorides.

22. M. L. Klein and R. D. Murphy, Phys. Rev. B, 6, 2433 (1972). 23. I. J. Zucker and G. G. Chell, J. Phys. C (Proc. Phys. Soc.), i, 1505 (1968). 24. J. A. Barker, M. L. Klein, M. V. Bobetic, et al., J. Phys. C: Solid State Phys., 4, L355 (1972). 25. j. A. Barker, R. A. Fischer, and R. O. Watts, Mol. Phys., 21, 657 (1971). 26. W. G. Hoover, A. C. Holt, and D. R. Squire, Physica, 44, 437 (1969). 27. Y. Waseda and M. Ohtani, Phys. Status Solidi (d), 52, K 37 (1972). 28. A. M. Al'shuler, Yu. Kh. Vekilov, and L. Z. Kimiat, Fiz. Tverd. Tela, 18, 836 (1976).

1. X-ray diffraction analysts and low-temperature DTA have confirmed the formation of the unstable rubidium hexachlorocerate(IV) which is easily hydrolyzed with the formation of Ce(III) derivatives. 2. It has been established that the Rb and Cs hexachlorocerates are isomorphous. 3. The preparation of the hexachlorocerates(IV) of Li, Na, and K was unsuccessful (according to the low-temperature data).

A brief analysis of various designs of power units shows that the partially self-contained power units are the simplest to manufacture. Here there is no need to solve such important problems as extra pure Pu238, i.e., having a minimum radiation effect on the body, protection of the body from this effect, dissipation of large quantities of heat, high cost, etc. Other requirements imposed on power units are also met considerably more simply in this case. However, the value of the self-contained AH as a means of returning the patient to normal activity surpasses many times that which can be expected from the partially self-contained AH. From this viewpoint, the scheme of a partially self-contained power unit with the use of a heat engine as a converter deserves special attention as it permits changing to a completely self-contained AH with minimum design changes.

The structure of the UF/sub 4/ molecule has been studied by gaseous electron diffraction. An analysis of the values of the mean amplitudes of the vibrations has indicated that its structure is not tetrahedral. The possible models of the molecule C/sub 3v/, D/sub 2d/, D/sub 4h/, C/sub 4v/ have been examined. The experimetal data show best agreement with the models with symmetry D/sub 2d/ and C/sub 3v/.

Interaction of XeF2 or XeF4 with MF (M = Na, K, Rb, Cs) has been studied. Hexafluoroxenates(IV) M2XeF6 containing the octahedral XeF62− anion (in accordance with spectroscopy data) were formed in the reaction. Cs2XeF6 and Rb2XeF6 form monoclynic crystals (a0 = 853.7(5); b0 = 669.6(2); c0 = 843.6(5) pm; β = 121.7(1)° and a0 = 812.6(4); b0 = 631.9(2); c0 = 795.6(4) pm; β = 121.5(1)°, respectively). K2XeF6 has a tetragonal lattice (a0 = 868.8(2); c0 = 747.8(2) pm), while Na2XeF6 has a hexagonal one (a0 = 642.1(3); c0 = 844.8(5) pm). M2XeF6 is shown to dissolve in unhydrous HF incongruently, one of the solvolitic products being XeF4. Thermolysis of M2XeIVF6 and M2XeVIF8 were shown to proceed under similar temperatures. Uber die Umsetzung der Di- und Tetrafluoride des Xenons mit Fluoriden der Alkalimetalle Die Umsetzung von XeF2 und XeF4 mit Verbindungen des Typs MF (M = Na, K, Rb, Cs) wird untersucht. Es bilden sich dabei Hexafluoroxenate(IV) mit der Summenformel M2XeF6, die das oktaedrische Anion XeF62− enthalten. Cs2XeF6 und Rb2XeF6 bilden monokline Kristalle (a0 = 853,7(5); b0 = 669,6(2); c0 = 843,6(5) pm; β = 121,7(1)° fur Cs2XeF6 und a0 = 812,6(4); b0 = 631,9(2); c0 = 795,6(4) pm; β = 121,5(1)° fur Rb2XeF6). K2XeF6: tetragonal mit a0 = 868,8(2); c0 = 747,8(2) pm; Na2XeF6: hexagonal mit a0 = 642,1(3); c0 = 844,8(5) pm. Es wird gezeigt, das sich die Verbindungen M2XeF6 inkongruent in wasserfreiem HF losen, wobei sich unter anderem das Solvolyseprodukt XeF4 bildet. Es wird nachgewiesen, das die Thermolyse von M2XeIVF6 und M2XeVIF8 unter ahnlichen Bedingungen ablauft.

Reaction of xenon di- and tetrafluoride with different transition element fluorocomplexes at high temperatures has been studied. The formation of XeIV anionic complexes M2XeF6 has been found. XeF4 is shown to reveal two kinds of properties: oxidative (higher than 300°C) and acidic (between 150-300°C), independently whether it was initially introduced into the system or arised in it from XeF2. The reaction path of xenon tetrafluoride is shown to depend upon the other reagent properties. The conclusion is made that Lewis acidic properties of xenon fluorides decrease as follows: XeF6 ≈ XeF4 ≫ XeF2. Uber die Saure-Base-Eigenschaften des Di- und Tetrafluorxenons in Reaktionen bei erhohten Temperaturen Es wurde die Reaktion von Xenondifluorid und Xenontetrafluorid mit Fluorkomplex-Verbindungen verschiedener Ubergangsmetalle bei erhohter Temperatur untersucht. Unter diesen Bedingungen wurde die Bildung von Anionenkomplexen M2XeIVF6 festgestellt. Es wurde gezeigt, das XeF4 unabhangig davon, ob es direkt in die Reaktion eingefuhrt wird oder dort aus XeF2 entsteht, zwei typische Eigenschaften aufweist: die eines Oxydationsmittels (> 300°C) und einer Saure (zwischen 150°C und 300°C). Das Reaktionsverhalten des XeF4 hangt ferner von den Eigenschaften des Reaktionspartners ab. Die Eigenschaften der Xenonfluoride als Lewis-Sauren folgen der Reihe: XeF6 ≈ XeF4 ≫ XeF2.

A complete assignment of all fundamentals in the spectra of crystalline R2CeCl6 belonging to the CeCl vibrations was undertaken using data about combination bands and active in the Raman spectrum overtones. The assumption of the presence of a separate [CeCl62−] group possessing an octahedral structure in crystals with a sufficient high site symmetry has been confirmed. Based on the experimental material and its interpretation a presumption concerning the appearence of a pseudo-Jahn-Teller effect in the hexachlorocerates(IV) was supposed. Schwingungsspektren kristalliner Hexachlorocerate(IV), R2CeCl6 Eine vollstandige Zuordnung aller Fundamentalbanden in den Spektren kristalliner R2CeCl6, die zu den CeCl-Schwingungen gehoren, wurde unter Benutzung von Daten uber Kombinationsschwingungen und im Raman-Spektrum aktiver Oberschwingungen vorgenommen. Die Vermutung uber die Existenz einer isolierten [CeCl62−]-Gruppe, die in Kristallen mit einer genugend hohen Gitterpunktsymmetrie eine oktaedrische Struktur aufweist, konnte bestatigt werden. Auf der Grundlage des experimentellen Materials und seiner Deutung wird die Vermutung uber das Auftreten eines Pseudo-Jahn-Teller-Effektes in der Hexachloroceraten(IV) geausert.

1. The heats of the reactions of xenon difluoride with fluoro complexes of RE(III) have been determined experimentally by the methods of DTA and mass spectrometry. The values of ArH for the thermolysis of MI3MIVF7 to MI3MIIIFI6 and F2have been found. 2. The values of the enthalpy changes according the α⇄ β transition of KHF2, the melting of KHF2, and the melting of XeF2 have been refined and found to be equal to 41.4±1.25, 26.7±2.60, and 19.0 ± 2.0 kJ/mole, respectively. 3. The series of the thermodynamic stability of the fluoro complexes of RE(IV) toward the elimination of a fluoride ion has been established.

XeF2 is shown to react with organomercury compounds, R2Hg (R = PhCC,p-MeOC6H4, p-Me2NC6H4, p-EtO2CC6H4 and PhCH2), with cleavage of the CHg bond. The products of the reaction are the following: Xe, RHgF (or RHgF/HgF2 mixture; for R = benzyl RHgF undergoes fast demercurization), RF (excluding R = PhCC), R2, and the products of radical, R·, reactions with solvents (dry CCl4 or CHCl3). The ease of reaction, about which one can judge from the temperature of the beginning of Xe evolution (given in brackets in °C), was found to decrease in the following sequence: R = PhCH2 (—45) p-Me2NC6H4, (—40), PhCC (—5), p-MeOC6H4 (5), p-EtO2CC6H4 (25). This sequence indicates XeF2 to be an electron acceptor and R2Hg an electron donor. It follows from the reaction mixture composition that the reaction goes via free radicals. The absence of fluorinated organomercury products in the reaction mixtures may be considered as evidence that XeF2 reacts more easily with the CHg bond than with CH or CC bonds. XeF2 reacts also with HgX2 (X = Cl, Br, I) under mild conditions to give X2, HgF2, and Xe in quantitative yields.