Phase-transfer Tsuji—Trost allylation of CH-acids with the assistance of palladium complexes with bidentate P<Superscript>III</Superscript>—N—P<Superscript>III</Superscript> ligands

The Tsuji—Trost allylation of CH acids, in particular, those of the YCH₂CO₂Et type (Y = CO₂Et, C(O)Me, CN), with allylic acetates in the K₂CO₃—DMF system in the presence of palladium catalysts with ligands RN(PPh₂)₂ (R = Ph, Prⁱ, c-C₆H₁₁) is accomplished.     

Quantum chemical study of formation of Cu<Superscript>II</Superscript>–Y<Superscript>III</Superscript> metallamacrocyclic complexes based on glycinehydroximate ligands

The process of solution-phase formation of the Cu^II–Y^III 15-metallacrown-5 complexes bearing the glycinehydroximate ligands has been for the first time investigated by methods of quantum chemistry. The DFT modeling at the B3LYP/DGDZVP (PCM) level was carried out for mono-, bi-, and tri-nuclear copper(II) complexes and also for heteronuclear Cu^II–Y^III derivatives as the metallamacrocycle precursors. The dependence of relative stability of these complexes on the Cu^II and Y^III coordination surroundings and also on the mutual positions of ligands was found. The structural (variations of interatomic distances and valence angles), electronic (changes in the atomic charges and electron density), and thermodynamical (enthalpies and Gibbs free energies) regularities of 15-metallacrown-5 formation were revealed. The key role of Y^III cation was established for the process of formation of the polynuclear metallamacrocyclic compound (15-metallacrown-5).     

Structure and stability of endohedral complexes <Superscript>4/2</Superscript>X@(HAlNH)<Subscript>2</Subscript> (X = N,P, As,C<Superscript>−</Superscript>, Si<Superscript>−</Superscript>)

The structures of a closo-hedral cluster (HAlNH)₁₂ and endohedral complexes ^4/2X@(HAlNH)₁₂ (X = N, P, As, C⁻, Si⁻) are studied by density functional theory (DFT) at the B3LYP/6-31G(d) level. The geometries, natural bond orbital (NBO), vibrational frequency (ν₁), energetic parameters, magnetic shielding constants (σ), and nucleus independent chemical shifts (NICSs) are discussed. It is found that all guest species are minima at the cage center. Inclusion energies (ΔE _inc) of all species are negative except those of ⁴N and ^4/2P. In all species, the endohedral quartet states (⁴X) are energetically less favorable than their doublet states (²X). The calculations predict that caged X states only donate <0.50 e to the cage and preserve their unencapsulated ground states.     

Syntheses and structures of six-coordinate K[Ga<Superscript>III</Superscript>(Cydta)] · 2H<Subscript>2</Subscript>O and K[Ga<Superscript>III</Superscript>(Pdta)] · 3H<Subscript>2</Subscript>O complexes

The title complexes, K[Ga^III(Cydta)] · 2H₂O(Cydta = trans-1,2-cyclohexanediaminetetraacetic acid) and K[Ga^III(Pdta)] · 3H₂O (Pdta = propylenediaminetetraacetic acid), were prepared, and their structures were studied by IR spectra, elemental analyses, NMR spectra, and single-crystal X-ray diffraction techniques. In the K[Ga^III(Cydta)] · 2H₂O complex, the Ga³⁺ is six-coordinated by the Cydta ligand yielding an octahedral conformation, and the complex crystallizes in the monoclinic system with the P2₁/c space group. The crystal data are as follows: a = 16.5039(19), b = 13.1499(16), c = 8.5204(10) Å, β = 101.650(2)°, V = 1811.0(4) ų, Z = 4, ρ = 1.757 g/cm³, μ = 1.805 mm^?1, F(000) = 984, R = 0.0291, and wR = 0.0698 for 3713 observed reflections with I ≥ 2σ(I). In the K[Ga^III(Pdta)] · 3H₂O complex, the Ga³⁺ is also six-coordinated by the Pdta ligand yielding an almost standard octahedral conformation, and the complex crystallizes in the orthorhombic system with P2₁2₁2₁ space group. The crystal data are as follows: a = 8.8913(10), b = 11.6181(13), c = 17.0227(19) Å, V = 1758.4(3) ų, Z = 4, ρ = 1.757 g/cm³, μ = 1.862 mm^?1, F(000) = 952, R = 0.0288, and wR = 0.0724 for 3556 observed reflections with I ≥ 2σ(I).     

Synthesis and structural determination of a novel complex [Yb<Superscript>III</Superscript>(HEgta)] · 4H<Subscript>2</Subscript>O in comparison with [Yb<Superscript>III</Superscript>(HEgta)] · 2H<Subscript>2</Subscript>O

One novel ytterbium complex [Yb^III(HEgta)] · 4H₂O (I), where H₄Egta = ethylene glycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid, has successfully been synthesized by the reaction of Yb₂O₃ with H₄Egta in an aqueous solution after refluxing for 18 h. The crystal and molecular structures were determined by the infrared spectrum and X-ray crystallography. The crystal structural analysis reveals that central Yb(III) in I is eight-coordinated in a geometry of pseudo-square antiprismatic polyhedron by two amine N atoms, two ethylene glycol O atoms, and four carboxyl O atoms from one HEgta ligand and crystallizes in the orthorhombic crystal system with P2₁2₁2₁ space group. The crystal data are as follows: a = 9.4927(8), b = 12.2627(13), c = 18.3657(17) Å, V=2137.9(4) ų, Z = 4, ρ_calcd = 1.934 mg/m³, μ = 4.448 mm^?1, F(000) = 1236, R = 0.0291, and wR = 0.0714 for 8850 observed reflections with I ≥ 2σ(I). In addition, there is a protonated coordinated carboxyl O atom (O(5)) in the [Yb^III(HEgta)] moiety.     

UV-sensitized nanomaterial semiconductor catalytic reduction of Co<Superscript>III</Superscript>(N–N)<Subscript>3</Subscript><Superscript>3+</Superscript>/nm-TiO<Subscript>2</Subscript> and Co:TiO<Subscript>2</Subscript> formation: SEM-EDX and HRTEM analyses

Interfacial electron transfer induced by 254 nm light at nanomaterial (nm) titanium dioxide/Co^III(N–N)₃ ³⁺ interface in binary mixed solvent media such as water/methanol (or 1,4-dioxane) has been probed. The distinct photo reduction of cobalt(III) complexes, Co^III(N–N)₃ ³⁺; (N–N)=(NH₃)₂, en (1,2-diamino ethane), pn (1,2-diamino propane), tn (1,3-diamino propane), and bn (1,4-diamino butane), by excited nm-TiO₂ particles: Co^III + nm-TiO₂ + hν → TiO₂ (h⁺;e⁻) + Co^III → nm-TiO₂ (h) + Co^II is solvent controlled. The electron transfer from the conduction band of TiO₂ (e⁻, CB) onto the metal centre of the complex consists of (i) electron transport from CB into surface-adsorbed species A: Co^III(N–N)₃ ³⁺ (ii) solution phase species B: Co^III(N–N)₃ ³⁺ _(sol.), accumulated at the surface of the nanoparticle. In addition, UV irradiation of Co^III(N–N)₃ ³⁺ stimulates generation of \textCo_\textaq^\textII {\text{Co}}_{\text{aq}}^{\text{II}} ion, due to charge transfer transition, in solution phase. After UV irradiation, cobalt-implanted nm-TiO₂ separated as gray ultrafine particles, which were isolated. Photo efficiency of the formation of Co^II ion was estimated and the cobalt implanted nanomaterial crystals isolated from the photolyte solutions were subjected to SEM-EDX, X-ray mapping, and HRTEM-SAED analyses. Solvent medium was found to contribute in both the formation of Co^II ion and interstitial insertion of cobalt into the lattice of nm-TiO₂.     

Synthesis of the [<Superscript>2</Superscript>H,<Superscript>15</Superscript>N]-labeled antiviral drug “triazavirine”

Selective methods for the incorporation of stable isotopes ¹⁵N and ²H into the structure of antiviral medicine “triazavirine” 1 were developed. The synthesized isotopically modified “triazavirine” 1– ² H ₃ , ¹⁵ N ₃ contained the labeled atoms in both the azole and the azine rings. ¹³C and ¹⁵N NMR spectra of the isotope-containing sample 1– ² H ₃ , ¹⁵ N ₃ were thoroughly analyzed.     

Thermodynamic Properties of Zincate-Manganites of LaM<Subscript>2</Subscript> <Superscript>II</Superscript>ZnMnO<Subscript>6</Subscript> (М<Superscript>II</Superscript> = Mg,Ca, Sr,Ba) Composition

Temperature dependences of the heat capacity of new zincate-manganites of LaM₂^IIZnMnO₆ (M^II = Mg, Ca, Sr, Ba) composition are studied via experimental calorimetry in the interval of 298.15–673 K. It is found that all compounds have λ-shape effects on the curve of dependence C_p° ~ ?(T) with respect to phase transitions of the second kind. Equations for the temperature dependence of the heat capacity are derived with allowance for phase transition temperatures, and thermodynamic functions H°(T) ? H°(298.15), S°(T) and Φ^xx(T) are calculated on the basis of experimental data on C_p°(T) and the calculated S°(298.15) value.     

Cyclotron production of <Superscript>211</Superscript>At/<Superscript>211g</Superscript>Po by <Superscript>209</Superscript>Bi(α,2n) reaction

Astatine-211 (T _1/2 = 7.214 h) is an α-emitter at secular equilibrium by EC with its ultra-short-lived α-emitting daughter, polonium-211g (T _1/2 = 0.516 s), with a high Linear Energy Transfer (LET — 130 eV·nm⁻¹) and a half-life suitable for metabolic radiotherapy; the overall α branching of the ²¹¹At/^211gPo system is 100%. The direct production of ²⁰⁹Bi(α,2n)²¹¹At/^211gPo seems the most satisfactory method; Bi targets were irradiated at JRC-Ispra Cyclotron of European Commission, EC, using α-energy higher than 28.61 MeV in order to produce, via ²⁰⁹Bi(α,3n) reaction, small amounts of the γ-emitter ²¹⁰At (used as internal spike).     

Preparation of <Superscript>235m</Superscript>U targets for <Superscript>235</Superscript>U(n,n′)<Superscript>235m</Superscript>U cross section measurements

This paper describes the preparation of samples for an experiment to measure the cross-section for ²³⁵U(n,n′)^235mU in a fast fission spectrum of neutrons provided by a fast pulsed reactor/critical assembly. Samples of ^235mU have been prepared for the calibration of the internal conversion electron detector that is used for the ^235mU measurement. Two methods are described for the preparation of ^235mU. The first method used a U-Pu chemical separation based on anion-exchange chromatography and the second method used an alpha recoil collection method. Thin, uniform samples of ^235mU+²³⁵U were prepared for the experiment using electrodeposition.     

Low-melting salts with the [Cr<Superscript>III</Superscript>(NCS)<Subscript>4</Subscript>(1,10-phenanthroline)]<Superscript>−</Superscript> complex anion: Syntheses,properties, and structures

Four new low melting salts, “Ionic Liquids” consisting of the [Cr^III(NCS)₄(Phen)]^? complex monoanion and imidazolium based cations A, with A = 1-ethyl-3-methylimidazolium (EMIm), 1-butyl-3-methylimidazolium (BMIm), 1,3-dimethyl-2,4,5-triphenylimidazolium (DML), and 1,2,3,4,5-pentamethyl-imidazolium (PMIm), were investigated. Single-crystal X-ray investigations established the structures of the four compounds. (EMIm)[Cr(NCS)₄(Phen)] (I): triclinic, \(P\bar 1\), a = 8.1382(6), b = 10.4760(8), c = 16.003(1) Å, α = 90.330(4)°, β = 94.759(4)°, γ = 107.305(4)°, Z = 2, R ₁(F)/wR ₂(F ²) = 0.0650/0.1770; (BMIm)[Cr(NCS)₄(Phen)] (II): triclinic, \(P\bar 1\), a = 8.5545(4), b = 9.8620(4), c = 16.6762(6) Å, α = 92.503(2)°, β = 97.517(2)°, γ = 91.249(2)°, Z = 2, R ₁(F)/wR ₂(F ²) = 0.0393/0.0848; (DML)[Cr(NCS)₄(Phen)] · C₃H₆O (III): triclinic, \(P\bar 1\), a = 11.0475(9), b = 13.589(1), c = 14.582(1) Å, α = 83.013(4)°, β = 87.116(4)°, γ = 70.333(5)°, Z = 2, R ₁(F)/wR ₂(F ²) = 0.0407/0.1023; (PMIm)[Cr(NCS)₄(Phen)] · C₃H₆O (IV): orthorhombic, Pbca, a = 17.379(1), b = 16.514(1), c = 22.304(1) Å, Z = 8, R ₁(F)/wR ₂(F ²) = 0.0460/0.1107 (in addition III and IV contain co-crystallized acetone molecules). Each compound was characterized by elemental analysis, NMR, IR, und UV-Vis spectroscopy. Magnetic properties were derived from NMR investigations (EVANS method). All four compounds are paramagnetic with effective magnetic moments of spin-only Cr^III. Melting points were obtained from DSC measurements. All melting points are higher than required for “Ionic Liquids”, but nevertheless “low” for molten salts.     

Production possibility of <Superscript>186</Superscript>Re via the <Superscript>192</Superscript>Os(p,α3n)<Superscript>186</Superscript>Re nuclear reaction

Experimentally measured cross-sections are presented for the first time for the ¹⁹²Os(p,α3n)¹⁸⁶Re nuclear reaction up to 67 MeV. Highly enriched thin ¹⁹²Os targets (15 pcs), prepared by electro-deposition onto Cu backings, were irradiated with an external proton beam delivered by the SSC cyclotron of iThemba LABS. The excitation function curve of the ¹⁹²Os(p,α3n)¹⁸⁶Re reaction shows a maximum cross-section of ~82 mb at about 24 MeV. According to the yield calculations based on the present results, the available cumulative no-carrier-added ¹⁸⁶Re yield is 7.76 MBq/μAh (0.21 mCi/μAh) over the energy region 13.4 → 27.3 MeV.     

Relativistic coupled cluster calculations of the electronic structure of KrH<Superscript>+</Superscript>, XeH<Superscript>+</Superscript> and RnH<Superscript>+</Superscript>

Potential energy curves of NgH⁺ cations (Ng = Kr, Xe, Rn) were obtained by using four-component relativistic CCSD(T) coupled cluster calculations. Dissociation energies, equilibrium bond lengths, electronic properties, such as dipole moments and electric field gradients at the nuclei, and the related spectroscopic parameters of the electronic ground state have been determined. The results obtained for KrH⁺ and XeH⁺ are in good agreement with available experimental data, while those for RnH⁺ have been determined for the first time at this level of theory.     

A simple and quick method for the preparation of radionuclide <Superscript>87</Superscript>Y/<Superscript>87m</Superscript>Sr generator using the <Superscript>nat</Superscript>Rb(α,xn)<Superscript>87</Superscript>Y reaction

A rapid method for the preparation of ⁸⁷Y/^87mSr radionuclide generator from a rubidium chloride target irradiated with 35 MeV α-particles is described. A simple two-step procedure is used to obtain a carrier-free ^87mSr isotope with a high enough radiochemical yield and high purity in the final aqueous fraction.     

Associative ionization reaction N + O → NO<Superscript>+</Superscript> + e<Superscript>–</Superscript> in slow collisions of atoms

The endothermic associative ionization reaction N(²D) + O(³P) → NO** → NO(¹Σ⁺) +e^- in slow collisions of the atoms has been considered in terms of the multichannel quantum defect theory. The dependences of the partial and total cross sections of the reaction on the energy of the colliding atoms in the range of 0–0.3 eV have been calculated. It has been shown that the cross sections have a pronounced resonance structure, which is formed as a result of the multichannel interaction of autoionization states of the intermediate Rydberg complex NO** with dissociative states. The temperature dependence of the reaction rate constant is presented. The results are compared with those of other calculations and available experimental data.     

Synthesis,structural and multinuclear natural abundance (<Superscript>13</Superscript>C, <Superscript>31</Superscript>P, <Superscript>195</Superscript>Pt) CP/MAS NMR studies of crystalline O,O′-dialkyldithiophosphate platinum(II) complexes

Platinum(II) O,O′-dicyclohexyl dithiophosphate [Pt{S₂P(O-cyclo-C₆H₁₁)₂}₂] (I) and platinum(II) O,O′-diisopropyl dithiophosphate [Pt{S₂P(O-iso-C₃H₇)₂}₂] (II) complexes were obtained and studied by solidstate ¹³C, ³¹P, and ¹⁹⁵Pt CP/MAS NMR spectroscopy. The dithiophosphate (Dtph) ligands in molecular structure I were found to be coordinated by platinum in S,S′-bidentate fashion to form the planar chromophore [PtS₄] (single-crystal X-ray diffraction data). For complex II, a new α-form (α-II) was obtained and identified by ³¹P MAS NMR spectroscopy. The ³¹P chemical shift anisotropy δ_aniso and the asymmetry parameter η of the ³¹P chemical shift tensor were calculated from the whole MAS spectra.     

Coordinatively Unsaturated Polynuclear Mixed-Valent Sn<Superscript>II</Superscript>–Sn<Superscript>IV</Superscript> and Cu<Superscript>II</Superscript>–Sn<Superscript>IV</Superscript> Oxo-Centered Carboxylates

The tetranuclear mixed-valent oxo-cluster [Sn^IISn^IVO(O₂CCF₃)₄]₂ (1) has been prepared by reacting SnCl₂ with AgO₂CCF₃ in a sealed ampoule at 90 °C. Alternatively, 1 was obtained by acidolysis of Ph₃SnSnPh₃ with trifluoroacetic acid in solution. The X-ray diffraction study of 1 revealed the presence of a Sn^IIOSn₂^IVOSn^II core comprised of the penta-coordinated divalent and six-coordinated tetravalent tin atoms. The ¹¹⁹Sn NMR studies confirmed the stability of the cluster in solution and the presence of two different oxidation states of tin. An acidolysis of Ph₃SnSnPh₃ in the presence of [Cu₂^II(O₂CCF₃)₄] followed by sublimation of the resulting product at 90 °C afforded the first trinuclear mixed metal Sn–Cu cluster [(C₆H₅)₂Sn₂^IVCu^IIO(O₂CCF₃)₆] (2). The X-ray diffraction analysis of 2 revealed the presence of two phenyl groups attached to the six-coordinated tin(IV) atoms and the tetragonal pyramidal environment of the copper(II) atom. Both complexes have been obtained free of exogenous ligands.     

Stability constants of zinc(II), cadmium(II), and cobalt(II) complexes of trimethylenediamine-<Emphasis Type="Italic">N,N,N′,N′</Emphasis>-tetraacetic acid

Stability constants of Zn²⁺, Cd²⁺, and Co²⁺ complexes of trimethylenediamine-N,N,N′,N′-tetraacetic acid were determined at 298.15 K and ionic strengths of 0.1, 0.5, and 1.0 by potentiometric titration. Potassium nitrate and chloride were used as supporting electrolytes. The results obtained were extrapolated to the zeroth ionic strength using an equation with one individual parameter, and the thermodynamic stability constants of the complexes were calculated. The results are compared with the corresponding data on related compounds.     

Crystallinity of Dynasan<Superscript>®</Superscript>114 and Dynasan<Superscript>®</Superscript>118 matrices for the production of stable Miglyol<Superscript>®</Superscript>-loaded nanoparticles

This study focuses on the physicochemical characterization of lipid materials useful for the production of the so-called solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC). The chosen lipids were Dynasan^®114 (glyceril trimyristate) and Dynasan^®118 (glyceril tristearate) as solid lipids (SL), melting temperature above 80 °C, and Miglyol^®812 (caprylic/capric triglyceride) and Miglyol^®840 (propylene glycol dicaprylate/dicaprate) as liquid lipids (LL), crystallizing below ?15 °C. Raw lipids (pure or SL:LL mixtures) were analyzed by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), and Polarized Light Microscopy (PLM), before and after tempering at 80 °C for 1 h. The selected SL:LL combination was 70% (Dynasan^®114 and 118) and 30% (Miglyol^®812 and 840) for the production of SLN and NLC by high-pressure homogenization (HPH), respectively. Particles with a mean size of 200 nm (polydispersity index <0.329) and zeta potential of ?15 mV were obtained, and their long-term stability was confirmed for 3 months of storage at 7 °C.     

Heat capacities and thermodynamic functions of new nanosized ferro-chromo-manganites LaM<Subscript>0.5</Subscript><Superscript>II</Superscript>FeCrMnO<Subscript>6.5</Subscript> (M<Superscript>II</Superscript>–Mg,Ca, Sr,Ba)

The heat capacities of nanosized ferro-chromo-manganites LaM_0.5 ^IIFeCrMnO_6.5 (M^II–Mg, Ca, Sr, Ba) are measured via dynamic calorimetry in the temperature range of 298.15–673 K using an IT-S-400 instrument. It is established that the C°_p~f(T) function of LaM_0.5 ^IIFeCrMnO_6.5 (M^II–Mg, Ca, Sr, Ba) has λ-type effects, due probably to phase transitions of the second order. Considering the temperatures of the phase transitions, equations of the heat capacity of ferro-chromo-manganites LaM_0.5 ^IIFeCrMnO_6.5 (M^II–Mg, Ca, Sr, Ba) as a function of temperature are derived on the basis of experimental data. Thermodynamic functions Н°(Т)–Н°(298.15), S°(Т), and Ф ^хх(Т) are calculated in the temperature range of 298.15–675 K.