Electrical conductivity and defect structure of Nd2O3+x

The electrical conductivity and departure from the stoichiometry of Nd₂O₃ have been measured over the temperature range of 900° to 1100°C and oxygen partial pressure of 1 to 10^?16 atm. The hole conductivity of Nd₂O₃ is found to be proportional to , where n are 4.6, 4.9, and 5.1 at 900°, 1000°, and 1100°C, respectively. From the oxygen partial pressure dependence of the hole conductivity, it is shown that the predominant point defects in nonstoichiometric NdO_1·+x are fully ionized and partially doubly ionized metal vacancies. From the thermogravimetric measurements, the departure from stoichiometry, x in NdO_1·5+x, is 2.0 × 10^?3 at 1000°C and 1 atm. By combining the electrical conductivity and weight change data, it is shown that the hole mobility is 6.3 × 10^?4 (cm²/V·sec) at 1000°C and 1 atm.     

The effect of environment on the reactions of thiiranium ions

The thiiranium ion formed by the reaction of $\text{Z}$-1-phenylpropene and (4-ClC₆H₄S)₂SC₆H₄ClSbCl₆ in CH₂Cl₉ at ?70°C reacts with Cl^? to form both $\text{erythro}$- and $\text{threo}$-Markownikoff B-chlorosulfides.     

Transient spectrum from nanosecond pulse radiolysis of liquid ammonia

In addition to the absorption of the ammoniated electron, the transient absorption spectrum of irradiated liquid ammonia contains two ultraviolet bands at 250 nm and 320 nm. The latter is shown to be due neither to the NH₂^? ion nor to NH singlet. There is conflicting evidence concerning its possible assignment to NH triplet. The C value of the ammoniated electron has been found to be 3.0 at ?48°C. At ?45°C, the ammoniated electron decays with concurrent first and second order kinetics and it reacts with Cu²⁺ with the rate constant 1.5 × 10¹¹$\text{l}$ mole^?1 sec^?1.     

Anionic polymerization with alkaline earth counterions—II Propagation kinetics of living poly-4-vinylpyridine

4-Vinylpyridine was polymerized by cumyl barium in THF at 0°C. Detailed conductance studies at various concentrations of the living oligomer solution gave similar experimental results as for 2-vinylpyridine, i.e. triple ions exist in thermodynamic equilibrium with free ions and ion pairs. The dissociation constant of ion pairs increases from 1.96 × 10^?10 M at 15°C to 4.35 × 10^?10 M at ?70°C with enthapy and entropy of dissociation of ?3.9 kJ/mol and ?200 J mol^?1 K^?1 respectively. The extent of dissociation of ion pairs of living oligo-4-vinylpyridine is comparable to that of living polystyrene ($\text{K}{}_1\text{? 10}{}^{\mathrm{?10}}$) but higher than that of living poly-2-vinylpyridine ($\text{K}{}_1\text{? 10}{}^{\mathrm{?11}}$). This result is interpreted in terms of intramolecular complexation which is no longer favourable when the nitrogen atom is situated at the 4-position of the pyridine nucleus. Studies of propagation kinetics revealed that 4-vinylpyridine polymerizes by the same reaction mechanism as the 2-isomer, the active sites being essentially ion pairs. At 0°C, its propagation constant was found to be 211.1 M^?1 sec^?1 compared with 151.04 M^?1 sec^?1 for living poly-2-vinylpyridine. As for free radical polymerization, the polymers contain only about 26% isotactic triads.     

Kinetics and mechanism of the reaction of Ba(No3)2 with TiO2(anatase) in the solid-solid state and the liquid-solid state

The reaction of Ba(NO₃)₂ with TiO₂(anatase) was studied by TG and DTA. According to simultaneous TG and DTA, the reaction occurred sharply around the melting temperature of Ba(NO₃)₂, ～577°C, at low heating rates, and the reaction followed after melting of Ba(NO₃)₂ as the rate was raised. For the isothermal reactions the conversion α vs time relationship was given by the equation: kt = 1 - (1-α)^1/3. The relationship was shown by one straight line below 577°C, and by two lines with a bend above 577°C. The reaction rates at the earlier period above 577°C were about $\text{1}\text{5}$ smaller than those at the later period, which were nearly on the extrapolated log k vs 1/T line obtained below 577°C. The activation energy was 212 kJ mol^?1 for the solid-solid reaction and 231 kJ mol^?1 for the earlier period in the liquid-solid reaction.     

Solvolytic behavior of p-dimethylamino-α-bromostyrene in water solutions

Nmr and UV studies show that $\text{p}$-dimethylamino-$\text{α}$-bromostyrene, I, undergoes S_Nl reaction in H₂O and HClO₄ (^kS_Nl = 6 × 10^?1sec.^?1 at 25°). The vinyl cation has an extraordinary selectivity for capture by aromatic amines relative to H₂O, including I itself to give the dimer II.     

Electrical conductivity in strontium titanate

The electrical conductivity of polycrystalline SrTiO₃ was determined for the oxygen partial pressure range of 10° to 10^?22 atm and temperature range of 800 to 1050°C. The data were found to be proportional to the $\text{?1}\text{6}\text{th}$ power of the oxygen partial pressure for the oxygen pressure range 10^?15–10^?22 atm, proportional to for the oxygen pressure range 10^?8–10^?15 atm, and proportional to for the oxygen pressure range 10⁰–10^?3 atm. These data are consistent with the presence of very small amounts of acceptor impurities in SrTiO₃.     

Electrochemical and kinetic study of oxygen in a perfluorotributylamine emulsion

Oxygen can be determined in a perfluorotributylamine emulsion used as a blood substitute by coulometry and polarography. The oxygen uptake of the emulsion (4.3 × 10^?3 mol l^?1 or 11 ml-% at 25°C and P_O2 = 760 mm Hg) is about three times greater than that of water. The adsorption of surfactant on a dropping mercury electrode changes the electrochemical parameters E_{$\text{1}\text{2}$}, α and k₃. The marked difference between the diffusion coefficients of oxygen and hydrogen peroxide (ratio 2.6) seems to be proceed from the ejection of oxygen molecules from the perfluorotributylamine droplets and from the insolubility of hydrogen peroxide molecules in the droplets. The constant rate of oxygen release by these droplets was estimated to be 10⁴ s^?1 by a stopped-flow spectrophotometric method. This constant rate seems to be linked with the particle diameter (0.2 μm) and the diffusion coefficient in the perfluorotributylamine droplets (1.6 × 10^?6 cm² s^?1).     

Epoxidation with the H2O2/vilsmeier reagent system

Alkenes $\text{1}$ a–d interact at ?80°C in 15 min. with the Vilsmeier reagent $\text{I}$ (Me₂N=CHCl)⁺PO₂Cl₂^? in presence of 30% H₂O₂ to yield the corresponding epoxides $\text{3}$ a–d. The reaction could involve the formation of the highly reactive hydroperoxymethylenedimethylammonium salt (Me₂N=CHOOH)⁺PO₂Cl^?₂$\text{II}$.     

The stepwise formation of complexes in the uranyl/azide system in aqueous medium

The use of an indirect potentiometric method with the glass electrode in a ₃?/HN₃/UO₂2+ solution leads to ligand number $\text{n}\text{?}$, at several azide concentrations, at 2.0M ionic strength (NaClO₄), aqueous medium and 25.0±0.1°C. The analysis of data under conditions where hydrolysis is avoided leads to the six overall stepwise constants: β₁ = 1.39 × 10²M^?1; β₂ = 8.26 × 10³M^?2; β₃ = 4.9 × 10⁵M^?3; β₄ = 7.1 × 10⁵M^?4; β₅ = 2.3 × 10⁶M^?5; β₆ = 1.2 × 10⁷M^?6.     

Thermodynamic parameters related to the specific adsorption of iodide ion on the mercury electrode

The thermodynamic functions for the specific adsorption of the iodide ion on mercury have been determined from capacity measurements at 5°C, 25°C and 45°C. The experimental values of the standard electrochemical free energy, enthalphy and entropy of adsorption at zero charge, Δ$\text{G}$⁰_I^?, Δ$\text{H}$⁰_I^?, and Δ$\text{S}$⁰_I^?, are in good agreement with previous values for chloride and thiocyanate ion adsorption. They show that most of the free energy change comes from the entropy change, suggesting that the structural contributions play an important role in the ion-specific adsorption. The thermodynamic functions are compared with the values calculated using the Andersen—Bockris model.     

Reactions of triphenylarsine oxide with aqueous hydrogen fluoride: Crystal structure of bis(triphenylarsine oxide)hydrogen(I) tetrafluoroborate

Fluorination of triphenylarsine oxide by aqueous hydrogen fluoride (1–40%) in the absence of glass readily gives triphenylarsine difluoride. When the reaction with dilute (1%) aqueous hydrogen fluoride is carried out in borosilicate glass apparatus, the glass participates in the reaction resulting in the formation of the crystalline 2:1 adduct 2Ph₃AsO·HBF₄. Crystals of this compound are monoclinic, $\text{P}$2₁/$\text{c}$, $\text{a}$ = 12.926(4), $\text{b}$ = 17.819(6), $\text{c}$ = 14.994(4) Å, β = 98.97(3)°, Z = 4. The structure contains cations [(Ph₃AsO)₂H]⁺ in which $\text{O}\text{?}$O is 2.44(2)Å, and anions BF₄^?.     

Synthesis,Reactions and Catalytic Activities of a Cationic Acrylonitrile-Rhodium(I) Complex

Reaction of RhCl (CO)(Ph₃P)₂(Ph₃P = triphenylphosphine) with AgClO₄ in acrylonitrile at 30°C produces a new cationic rhodium(I) complex, [Rh(CH₂CHCN)(CO) (Ph₃P)₂]ClO₄ ($\text{1}$) and AgCl. The ¹H-NMR and IR spectra of $\text{1}$ suggest that acrylonitrile is coordinated to rhodium through the π-system of the vinyl group. The complex $\text{1}$ reacts with molecular hydrogen to give a propionitrile-rhodium(I) complex, [Rh(CH₃ CH₂CN) (CO)(Ph₃P)₂ClO₄($\text{2}$) where the coordination of propionitrile through nitrogen is suggested by the ¹H-NMR and IR spectral data. The coordinated acrylonitrile in $\text{1}$ is readily replaced with triphenylphosphine and propionitrile to give [Rh(CO)(Ph₃P)₃] ClO₄ and $\text{2}$, respectively. The complex $\text{1}$ is catalytically active for the hydrogenation and polymerization of acrylonitrile at 25°C under the atmospheric pressure of hydrogen.     

Polarography of disodium pentacyanonitrosylferrate(II): Part 2. Determination at Therapeutic Levels in Serum,Plasma, and Whole Blood

Disodium pentacyanonitrosylferrat(II) (sodium nitroprusside) is determined at therapeutic (ng ml^?1) levels in plasma, serum and blood with conventional and high-performance differential pulse polarography (d.p.p. and h.p.d.p.p.) at a dropping mercury electrode or a static mercury drop electrode. Serum or plasma (3 ml) is treated with perchloric acid containing 1 mg ml^?1 potassium hexacyanoferrate(II), centrifuged for 10 min and subjected to polarography. For spiked serum, calibration graphs are linear over the range 30–1000 ng ml^?1 sodium nitroprusside, regardless of the polarographic technique; the estimated detection limit is 15 ng ml^?1 (5 × 10^?8 M). Calculated therapeutic levels range from 100 to 1000 ng ml^?1. Similar results were obtained for spiked plasma. A similar procedure is suitable for whole blood and was used to study the in-vitro degradation of sodium nitroprusside (200 ng ml^?1) on incubation at 37°C. The in-vitro loss is rapid (t_{$\text{1}\text{2}$} ≈ 6 min) but meaningful in-vivo levels can be obtained when the blood is collected in a 0.9% sodium chloride solution at 0°C. Thiocyanate, the main metabolite of nitroprusside, and thiosulphate, which is a potential antidote for cyanide, do not interfere.     

Synthesis,characterization, and crystal structure of a new truly one-dimensional compound: PV2S10

PV₂S₁₀ was obtained by heating the elements in stoichiometric proportions at 490°C in evacuated Pyrex tubes. The crystal symmetry is monoclinic, space group $\text{P2}{}_1\text{c}$, with the unit cell parameters a = 12.734(8)Å, b = 7.349(7)Å, c = 23.662(4)Å, β = 95°22(1), V = 2205(4)ų, and Z = 8. The structure was solved from 2269 independant reflexions, and anisotropic least squares refinement gave R = 0.036 with 236 variables. The structure can be described as made of [V₂S₁₂] units forming endless chains themselves linked, two by two, by [PS₄] tetrahedra. In these units each vanadium is surrounded by eight sulfur atoms (mean d_VS = 2.459Å) arranged in a distorted bicapped triangular prism. Two of these prisms shared a rectangular face to form [V₂S₁₂] groups, in which intercationic distances implied vanadium-vanadium bonds (mean d_VV = 2.852(2)Å). Between the infinite double chains, only SS weak van der Waals' bonds exist. More than two thirds of the sulfur atoms are present as [SS]^?II pairs, (mean d_SS = 2.015Å); the rest are S^?II anions.     

The molecular structure of [dimethyl(phenyl)silyl]tris(trimethylsilyl)methane

The structure of the crowded molecule (Me₃Si)₃C(SiMe₂Ph) has been determined by single crystal X-ray diffraction. The steric strain manifest itself mainly in lengthening of the Me₃SiC and Me₂PhSiC bonds (average length 1.920(6) $\text{,ac>A}\text{?}$) and closing up of the CSiC angles within the Me₃Si and Me₂PhSi groups (average 105.2(10)°), with correspondingly large C(1)SiC angles (113.5(13)°; C(1) is the central carbon atom).     

Electrical conductivity in calcium titanate

The electrical conductivity of polycrystalline CaTiO₃ was measured over the temperature range 800–1100°C while in thermodynamic equilibrium with oxygen partial pressures from 10^?22 to 10⁰ atm. The data were found to be proportional to the $\text{?}\text{1}\text{6}\text{th}$ power of the oxygen partial pressure for the oxygen pressure range 10^?16 – 10^?22 atm, proportional to for the oxygen pressure range 10^?8 – 10^?15 atm, and proportional to for the oxygen pressure range greater than 10^?4 atm. The region of linearity where the electrical conductivity varies as $\text{?}\text{1}\text{4}\text{th}$ power of P_O2 increased as the temperature was decreased. The observed data are consistent with the presence of small amounts of acceptor impurities in CaTiO₃. The band-gap energy (extrapolated to zero temperature) was estimated to be 3.46 eV.     

Détermination par spectrophotométrie d'absorption du potentiel normal du couple Cu(II)/Cu(I) dans les chlorures alcalins fondus

The reaction Cu²⁺ + Cl^? ? Cu⁺ + $\text{1}\text{2}$ Cl₂ has been studied in three different solvents—LiCl—KCl (70–30 % mol), eutectic LiCl–KCl (58–42 % mol) and LiCl–CsCl (55–45 % mol) at different temperatures by visible and near i.r. spectrophotometry. Equilibrium constants are calculated. The standard potential of the couple Cu²⁺/Cu⁺ with reference to the standard potential of Cl₂/2Cl^?, as well as the thermodynamic quantities $\text{Δ}\text{H}$ and $\text{Δ}\text{S}$ in the range 400–600 °C, have been deduced.     

Leitfähigkeit dotierter (μ-1,4-diisocyanobenzol)phthalocyanina toeisen(II)-verbindungen

Conductivity of doped (μ-1,4-diisocyanobenzene)phthalocyaninatoiron(II)-compounds. - The (μ-1,4-diisocyanobenzene)phthalocyaninatoiron(II)-compounds $\text{2a}$, $\text{3a}$, $\text{5a}$ and $\text{6a}$ are doped with iodine leading to air stable powders which are stable up to 100°C. They were characterized by elemental analyses, TGA/DTA, IR-, resonance Raman- and ⁵⁷Fe-Mössbauer spectroscopy. Increasing dopant levels result in higher electronic conductivities up to 10^?2 S/cm and in decreasing activation energies.     

The crystal structure of tris(triphenylphosphine)gold(I)-[dodecahydrido-6-thia-nido-decaborate(1—)]

The crystal structure of tris(triphenylphosphine)gold(I)[dodecahydrido-6-thia-nido-decaborate(1—)], [(C₆H₅)₃P]₃AuB₉H₁₂S, has been determined using X-ray techniques and counter data. The compound is a salt consisting of [(C₆H₅)₃P]₃Au⁺ cations and B₉H₁₂S^? anions. The cation is trigonal and nearly planar with AuP distances of 2.382(5) Å and PAuP anglés of 119.3(36)°. The B₉H₁₂S^? thiaborane anion is an open icosahedral fragment with the S atom in the 6 position, on the periphery of the decaborane polyhedron. The structure is the same as that found in solution for the isoelectronic B₁₀H₁₄^2? anion. Crystals are triclinic, space group P$\text{1}$, with a = 13.086(12), b = 19.635(32), c = 11.180(8) Å, α = 103.60(16), β = 72.10(9), and γ = 94.76(15)°. The structure was refined by least squares to a conventional R of 0.077.