Synthesis,Spectral Properties,and Crystal Structure of {Methoxo[4-phenylbutane-2,4-dione(p-nitrobenzoyl) hydrazonato(2-)]oxovanadium(V)}

The hydrazino complex {methoxo[4-phenylbutane-2,4-dione(p-nitrobenzoyl)hydrazonato(2-)]oxovanadium(V)}, VO(p-NO₂bhbzac)OCH₃, (1), has been prepared by the direct reaction of bis(benzoylacetonato) oxovanadium(IV), VO(bza)₂, with p-NO₂-C₆H₄C(O)NHNH₂, p-NO₂bh, in CH₃OH. The resulting compound contains benzoylacetone-(p-NO₂)benzoyl hydrazone as tridentate Schiff base-type ligand and OCH₃ group as Lewis base, both ligated to vanadium. The crystals are orthorhombic, with Z = 8, space group Pbca, a = 11.699(5) Å, b = 14.035(5) Å, c = 22.564(5) Å, R1 = 0.0756 and wR2 = 0.1302. The crystal structure demonstrated the square-pyramidal geometry of the VO_oxo(ONO)O coordination sphere with the oxo ligand at the apical position. The electronic absorption spectra revealed a ligand-to-metal charge-transfer (LMCT) band in the near UV region at _max = 23,700 cm^–1 (B = 5640 dm³ mol^–1 cm^–1) in CH₃CN, _max = 23,420 cm^–1 (B = 5550 dm³ mol^–1 cm^–1) in DMSO, and _max near 26,950 (sh) cm^–1 (B = 10,550 dm³ mol^–1 cm^–1) in CH₂Cl₂. The FT-IR spectra of (1) show the characteristic strong (V = O) stretching vibration at 993 cm^–1 and support the view that the oxovanadium complex is pentacoordinated and monomeric.     

Gas-phase reactions of SF5, SF2, and SOF with O(3 P): Their significance in plasma processing

Reactions of both SF₅ and SF₂ with O(³ P) and molecular oxygen have been studied at 295 K in a gas flow reactor sampled by a mass spectrometer. For reactions with O(³ P), rate coefficients of (2.0±0.5)×10^–11 cm³ s^–1 and (10.8±2.0)×10^–11 cm³ s^–1 were obtained for SF₅ and SF₂ respectively. The rate coefficients for reactions with O₂ are orders of magnitude lower, with an estimated upper limit of 5×10^–16 cm³ s^–1 for both SF₅ and SF₂. Reaction of SF₂ with O(³ P) leads to the production of SOF which then reacts with O(³ P) with a rate coefficient of (7.9±2.0)×10^–11 cm³ s^–1. Both SO and SO₂ are products in the reaction sequence initiated by reaction between SF₂ and O(³ P). Although considerable uncertainty exists for the heat of formation of SOF, it appears that SO arises only from reaction between SOF and O atoms which is also the source of SO₂. These results are discussed in terms of a reaction scheme proposed earlier to explain processes occurring during the plasma etching of Si in SF₆/O₂ plasmas. A comparison between the results obtained here and those reported earlier for reactions of both CF₃ and CF₂ with O and O₂ shows that there is a marked similarity in the free radical chemistry which occurs in SF₆/O₂ and CF₄/O₂ plasmas.     

Silylating Agents Grafted onto Silica Derived from Leached Chrysotile

Silica from leached chrysotile fibers (SILO) was silanized with trialkoxyaminosilanes to yield inorganic–organic hybrids designated SILx (x=1–3). The greatest amounts of the immobilized agents were quantified as 2.14, 1.90, and 2.18 mmol g⁻¹ on SIL1, SIL2, and SIL3 for –(CH₂)₃NH₂,–(CH₂)₃NH(CH₂)₂NH₂, and –(CH₂)₃NH(CH₂)₂NH(CH₂)₂NH₂ groups attached to the inorganic support. The infrared spectra for all modified silicas showed the absence of the Si–OH deformation mode, originally found at 950 cm⁻¹, and the appearance of asymmetric and symmetric C–H stretching bands at 2950 and 2840 cm⁻¹. Other important bands associated with the organic moieties were assigned to ν_as(NH) at 3478 and ν_sym(NH) at 3418 cm⁻¹. The NMR spectrum of the solid precursor material suggested two different kinds of silicon atoms: silanol and siloxane groups, between −90 and 110 ppm; however, additional species of silicon that contain the organic moieties bonded to silicon at −58 and −66 ppm appeared after chemical modification. These modified silicas showed a high adsorption capacity for cobalt and copper cations in aqueous solution, in contrast to the original SILO matrix, confirming the unequivocal anchoring of silylating agents on the silica surface.     

Co-hydrolysis products of tetraethoxysilane and methyltriethoxysilane in the presence of tetramethylammonium ions: Part 2 [1]

²⁹Si NMR peaks due to species with the double four-membered ring siloxane backbone composed of both Si(O^–)_4/2 and CH₃Si(O^–)_3/2 units, (CH₃) _n Si₈O _{20 – n} ^{/(8 – n) –} (n=1–3), formed by co-hydrolysis of tetraethoxysilane and methyltriethoxysilane in the presence of tetramethylammonium ions in methanol have been assigned. It has been found that ²⁹Si NMR peaks due to Si(OSi)₃(O^–) units shift to lower frequencies by replacement of the adjacent Si(O^–)_4/2 units by CH₃Si(O^–)_3/2 units, in other words, with increasing m value in Si[OSi(O^–)₃]_{3 – m} [OSi(CH₃) (O^–)₂] _m (O^–) (m=0–2). Peaks from CH₃ Si(OSi)₃ units in the species have also appeared as separated due to the kind of neighbor structural units. On the basis of the assignments, positions of CH₃Si(O^–)_3/2 units in the cubic octameric siloxane framework of (CH₃) _n Si₈O _{20 – n} ^{/(8 – n) –} (n=2, 3), for both of which three isomers are present, have been estimated.     

Temperature dependence of the probabilities of VV energy exchange between H2 and DCl

The temperature dependence of the removal of the vibrational energy of H₂ by DCl in H₂(1) + DCl(0) has been investigated over the range of 300–3000 K. The energy transfer probability of H₂(1) + DCl(0) → H₂(0) + DCl(1), where the vibrational energy of H₂(1) is removed by both the vibrational and rotational motions of DCl(0), is found to be strongly temperature dependent and increases with temperature closely following the relation log P α T^1/3. Over the temperature range it changes by two orders of magnitude. The probability of the near-resonant process H₂ (1) + DCl(O) → H₂(0) + DCl(2) is very close to that of the former at 300 K, but it increases only slightly as the temperature is raised to 3000 K. The sum of the probabilities of these two processes at 300 K is 3.4 × 10^?5, which agrees with the experimental value of 3.95 × 10^?5.     

The solubility and isotopic fractionation of gases in dilute aqueous solution. IIa. solubilities of the noble gases

A method for the analysis of precise gas solubility data is presented and applied to new determinations of the Henry constant, k₂, for He, Ne, Ar, Kr, and Xe. The values of k₂ are fitted to the same sets of temperature functions which we have tried for oxygen. Our previously proposed power series in 1/T, ln(k_2/P )=a₀+a₁/T+a₂/T² (Mark I), gives the best 3-term fit within the temperature range 0–60°C. For use over the full range to the critical temperature of water, we have discovered a new function given by (T^*)²ln(k_2/P )=A₀(T^*)²+A₁(1-T^*)^1/3+A₂(1-T^*)^2/3(Mark II), where T^*T/T _c1 . It fits our data from 0–60°C nearly as well as Mark I; it fits high temperature data from other sources; and at the critical temperature of water it satisfies theoretical requirements. Expansion of Mark II reveals the relationship between Mark II and Mark I and leads to a 4-term smoothing function, ln(k_2/P )=a_–2(T^*)^–2+a_–1(T^*)^–1+a₀+a₁T^* (Mark III), which we believe gives the best values only for the 0–60°C range. Mark III is used to calculate values for , and , 0–60°C, and a procedure is empolyed to estimate the errors. Agreement is excellent between these results and those obtained from precise microcalorimetric measurements made by others. With the inclusion of pressure correction terms, Mark II yields the four thermodynamic function changes for use at high temperatures. With increasing temperature, these changes suddenly turn upward toward plus infinity as T _c1 is approached. Essentially direct determinations of for argon by other workers are in excellent agreement with our results. The symmetrical activity coefficient at infinite dilution, ₂ ^° is examined and the hypothetical properties of k₂ are explored below 0°C. Mark II can be expressed in the reduced form (T^*)²ln(k ₂ ^* )=A₁(1-T^*)^1/3+A₂(1-T^*)^2/3, where k ₂ ^* k ₂/(p _c12c1). A₂ is a very good linear fit to A₁, which suggests a characteristic temperature for water at 287.3 K.     

Estimated ionicB-coefficients from NMR measurements in aqueous electrolyte solutions

¹⁷O-NMR spin-lattice relaxation timesT ₁ of D₂O molecules were measured at 5–85°C in D₂O solutions of alkali metal halides (LiClCsCl, KBr, and KI), DCl, KOD, Ph₄PCl, NaPh₄B, and tetraalkylammonium bromides (Me₄NBrAm₄NBr) in the concentration range 0.1–1.4 mol-kg^–1 TheB-coefficients of the electrolytes obtained from the concentration dependence of relaxation ratesR ₁=1/T₁ were divided into the ionicB-coefficients by three methods: (i) the assumption ofB (K⁺)=B(Cl^–), (ii) the assumption ofB(Ph₄P⁺)=B(Ph₄B^–), and (iii) the use ofB(Br^–) obtained from a series ofB(R₄NBr). It was found that Methods (ii) and (iii) resulted in an abnormal temperature dependence of theB-coefficients of alkali metal ions and a negative values of rotational correlation times _c at lower temperatures for hydroxide and halide ions. These results suggest that the methods based on the van der Waals volume are not adequate for the ionic separation of NMRB-coefficients. From the analysis using the assumption ofB(K⁺)=B(Cl^–), it was found that D₃O⁺, OD^–, and Me₄N⁺ ions are the intermediates between structure makers and breakers, and that the hydrophobicity of phenyl groups is weaker than that of alkyl groups due to the interactions between water molecules and -electrons in phenyl groups.     

Reaktionen mit phosphororganischen Verbindungen, 17. Mitt.: Zur Oxydation von β-Oxophosphoniumrhodaniden mit Bleitetraacetat

Zusammenfassung Die Oxydation von Phosphoniumrhodaniden (C₆H₅)₃P–CH (Alkyl) CO–CHR₁R₂ SCN mitPbTA liefert in Abhängigkeit von den Resten R₁ und R₂ Verbindungen des Typs R₁R₂C=C=C (SCN) (Alkyl) und die daraus durch 1,3-Umlagerung resultierenden Senföle R₁R₂C(NCS)–CC-Alkyl. Für R₁=R₂=H und R₁=Cl, R₂=C₂H₅ entsteht fast nur die Allenverbindung. Für R₁=H und R₂=Alkyl isoliert man ein Gemisch aus Allenrhodanid und Acetylenverbindung. Wenn R₁=R₂=(–CH₂–CH₂–CH₂–) oder CH₃ darstellen, kommt es zur ausschließlichen Bildung des Acetylensenföls.Aus -Methoxyphosphoniumrhodaniden (C₆H₅)₃P–CH (OCH₃)CH–CHR₁R₂ SCN erhält man bei der Umsetzung mitPbTA R₁R₂CH–CO–CH(OCH₃) (NCS) und R₁R₂CH–CO–CH(OCH₃) (S–CO–CH₃).

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The oxidation of phosphoniumrhodanides (C₆H₅)₃P–CH (Alkyl)CO–CHR₁R₂ SCN with lead tetraacetate results in the formation of R₁R₂C=C=C=(SCN) (alkyl) type compounds, dependent on the substituents R₁ and R₂ sometimes followed by a 1,3-rearrangement to mustard oils R₁R₂C(NCS)–CC–alkyl. The case R₁=R₂=H and R₁=Cl, R₂=C₂H₅ yields almost exclusively the allenic compound. With R₁=H and R₂-alkyla mixture of allene rhodanide and the acetylenic compound is isolated. If R₁ and R₂ stand for –CH₂–CH₂CH₂– or CH₃, only the mustard oil with an acetylenic group is produced.Upon the oxidation of (C₆H₅)₃P–CH(OCH₃)CO–CHR₁R₂ SCN^– we observed formation of R₁R₂CH–CO–CH(OCH₃) (NCS) and R₁R₂CH–CO–CH(OCH₃) (S–CO–CH₃).

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Mit 5 Abbildungen

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Herrn Prof. Dr.L. Schmid zum 70. Geburtstag gewidmet.

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16. Mitt.:Elisabeth Werner undE. Zbiral, Angew. Chem.79, 899 (1967).     

Mixed Complex Salt [Cu4(SCN2H4)7(NO3)](NO3)(SO4) · 3.3H2O: Synthesis and X-Ray Diffraction Analysis

The complex salt [Cu₄(SCN₂H₄)₇(NO₃)](NO₃)(SO₄) · 3.3H₂O was synthesized via reaction of aqueous solutions of thiourea with copper nitrate at 80°C and studied using X-ray diffraction analysis. The conditions and reasons for the partial oxidation of thiourea to sulfate ions were established. The crystals are monoclinic: a = 12.6072(7) Å, b = 15.4265(8) Å, c = 22.108(1) Å, = 120.133(6)°, space group P2₁/c, Z = 4. The crystal structure consists of [Cu₄(SCN₂H₄)₇(NO₃)]³⁺ complex cations, SO₄ ^2–, and NO₃ ^– anions, and molecules of the water of crystallization. Three types of coordination of the Cu atom were distinguished in the structure: trigonal (Cu–S 2.213–2.279 Å), tetrahedral (Cu–S 2.315–2.459 Å), and trigonal–pyramidal (3+1) (Cu–S 2.26–2.288, Cu–O 2.68 Å). The NO₃ ligand was found to be orientationally disordered.     

Quantum yield of Cl* (2P1/2) production in the gas phase photolysis of CCl4 in the ultraviolet

In this paper, we have probed the dynamics of chlorine atom production from the gas phase photodissociation of carbon tetrachloride at 222 and 235 nm. The quantum yield, φ* of Cl* (²P_1/2) production has been determined by probing the nascent concentrations of both excited (²P_1/2) and ground state (²P_3/2) chlorine atoms by suitable resonance-enhanced multiphoton ionization (REMPI) detection schemes. Although at the photolysis wavelengths the absorption of carbon tetrachloride is weak, significant amounts of Cl* are produced. Surprisingly, the quantum yield of Cl* production does not follow the absorption spectrum closely, which gives rise to the possibility of an indirect dissociation mechanism present in CCl₄ along with direct dissociation at these ultraviolet wavelengths     

Synthesis,characterization and charge-transfer photochemistry of trans-aquo azido-N,N′-trimethylenebis(naphthylideneiminato)chromium(III)

A new Cr^III complex, viz. trans-[Cr(naphprn)(H₂O)₂]ClO₄·2H₂O, (1) {naphprn=N,N-trimethylenebis(naphthylideneimine)} has been synthesized and characterized. Aquo ligand substitution of ( 1 ) by the azide ligand gave rise to trans-[Cr(naphprn)(N₃)(H₂O)], ( 2 ). Irradiation of ( 2) in DMF gave nitrido(naphprn)chromium(V) ( 3 ). Solutions of ( 3 ) showed e.p.r. spectra at room temperature (g _iso=1.9865). The i.r. spectra showed disappearance of a band at 2067cm^–1 showing the breakdown of NN and appearance of a new band at 1074cm^–1which is assigned to the Cr¹⁴N, stretching frequency indicating the formation of a nitrido chromium(V) complex, ( 3). The u.v.–vis. spectrum of complex ( 3 ) exhibited a d–d band maximum at 553nm (=120M^–1cm^–1). The rate of formation of ( 2 ) was found to be 5.0×10^–3M^–1s^–1 in an aqueous acidic medium at [Cr^III]=0.5×10^–3M; [N₃ ^–]=0.01–0.15M; [H⁺]=0.001M and I=0.2M (LiClO₄). The rate of photo-decomposition of ( 2 ) to give rise to ( 3 ) was found to be 0.15×10^–3s^–1 in DMF.     

Kinetics of Sulfur Oxide, Sulfur Fluoride, and Sulfur Oxyfluoride Anions with Ozone

Rate constants and product branching ratios were measured for eleven sulfur oxide, sulfur fluoride, and sulfur oxyfluoride anions reacting with O₃. The SO^– ₂ ion reacts rapidly to form –O^– ₃, SO^– ₃, and e^–. The temperature dependence of the branching ratio shows more reactive detachment and less SO^– ₃ formation at higher temperature. SO^– ₃ reacts with O₃, forming SO^– ₄ at 1/3 to 1/4 of the collisional rate from 200 to 500 K, respectively. At 300 K, SF^– ₆ charge transfers to O₃ at 20% of the collisional rate. F₂SO^– ₂ reacts with O₃ at a few percent of the collision rate, forming both O^– ₃ and FSO^– ₃; The ion F₃SO^– reacts slowly with O₃ to form F₃SO^– ₂. The ions SO^– ₄, SF^– ₅, FSO^– ₂, FSO^– ₃, F₃SO^–, and F₅SO^– are unreactive with O₃. A trend is noted relating the ion reactivity with the coordination of the central sulfur atom, i.e., the number of S–F bonds plus two times the number of S=O bonds. Only ions with a sulfur coordination of 4 or 6 are reactive, although the reaction rate constants are generally small. The reactivity trends appear to be partially explained by spin conservation. These reactions are all sufficiently slow, so O₃ reactions should not play a major role in SF₆/O₂ discharges. All ions studied have been found to be unreactive with O₂.     

Kinetics of the anation reaction of pentaamineaquacobalt(III) by phosphorous acid/hydrogenphosphite

Summary The kinetics of the anation reaction of [Co(NH₃)₅H₂O]³⁺ by H₃PO₃/H₂PO ₃ ^– , to give [CoH₂PO₃(NH₃)₅]²⁺, have been studied at 60, 70 and 80°C, in the acidity range [H⁺](M)=1.5 · 10^–1 –2.0 · 10^–3. Only H₂PO₃ is found to be reactive. The rate data is consistent with an I_d mechanism. The mean value of outer sphere association of [Co(NH₃)H₂O]³⁺ with H₂PO ₃ ^– is 1.5 M^–1. Values of the interchange constants are: 10⁴4k_i(s^–1)= 0.29, 1.47, 5.13, at 60, 70 and 80 °C respectively (H= 1.4 · 10²KJmol^–1, S=8.3 · 10 JK^–1 mol^–1). The first acidity constant of H₃PO₃ at I=1.0 has also been determined: 10²K_a(M)=4.8, 5.2 and 5.5, at 25, 40 and 50 °C respectively.     

Glass–ceramic Li2S–P2S5 electrolytes prepared by a single step ball billing process and their application for all-solid-state lithium–ion batteries

We report that glass–ceramic Li₂S–P₂S₅ electrolytes can be prepared by a single step ball milling (SSBM) process. Mechanical ball milling of the xLi₂S·(100 − x)P₂S₅ system at 55 °C produced crystalline glass–ceramic materials exhibiting high Li-ion conductivity over 10⁻³ S cm⁻¹ at room temperature with a wide electrochemical stability window of 5 V. Silicon nanoparticles were evaluated as anode material in a solid-state Li battery employing the glass–ceramic electrolyte produced by the SSBM process and showed outstanding cycling stability.     

Pulverized coal plasma gasification

A number of experiments on the plasma-vapor gasification of brown coals of three types have been carried out using an experimental plant with an electric-arc reactor of the combined type. On the basis of the material and heat balances, process parameters have been obtained: the degree of carbon gasification (_c), the level of sulfur conversion into the gas phase (_s), the synthesis gas concentration (CO+Hz) in the gaseous products, and the specific power consumption for the gasification process. The degree of gasification was 90.5-95.0%, the concentration of the synthesis gas amounted to 84.7–85.7%, and the level of sulfur conversion into the gas phase was 94.3–96.7%. Numerical study of the process of plasma gasification of coals was carried out using a mathematical model of motion, heating, and gasification of polydisperse coal particles in an electric-arc reactor of the combined type with an internal heat source (arc). The initial conditions for a conjugate system of nonlinear differential equations of the gas dynamics and kinetics of a pulverized coal stream interacting with the electric arc and oxidizer (water vapor) agree with the initial conditions of the experiments. The computation results satisfactorily correlate with the experimental data. The mathematical model can be used for the determination of reagent residence time and geometrical dimensions of the plasma reactor for the gasification of coals.Nomenclature c _i volume concentration of components (kmol m^–3) - x longitudinal coordinate (m) - f _i source members, determined by variation of the ith component due to chemical reactions in unit volume in unit time (kmol m^–3s^–1) - velocity (m s^–1) - M _s ash mass in one particle (kg) - C _D particle drag coefficient - 3.14 - r _s particle radius (m) - d particle diameter (m) - density (kg m^–3) - C _p heat capacity of components (J mol^t– K^–1) - Q _j thermal effect of reaction (J kmol^–1) - E_j activation energy of reaction - N _l volume concentration of particles of thelth fraction (m^–3) - T temperature (K) - emissivity factor of coal particles - 5.67 × 10^–8, blackbody emissivity coefficient (W m^–2 K^–4) - P pressure (Pa) - S reactor cross section (m²) - D reactor diameter (m) - V reactor volume (m³) - L _R reactor length (m) - F _W friction force on the wall (N) - f _g friction coefficient - residence time (s) - Nu Nusselt number - Re Reynolds number - Pr Prandtl number - thermal conductivity of gas (J m^– s^–1 K^–1) - R 8.3 × 10³, universal gas constant (J kmol K^–1) - µ _i molecular mass of component (kg kmol^–1) - dynamic viscosity coefficient of gas (kg m^–1 s^–1) - thermal efficiency of plasma reactor - q_arc specific heat flow from arc (W m^–3) - P ₁ heat supplied in vapor at T = 405 K (W) - P ₂ heat loss to wall (W) - P ₃ heat loss in the gas and slag separator chamber (W) - P ₄ heat loss in the synthesis gas oxidation chamber (W) - P ₅ heat loss in the slag catcher (W) - P ₆ heat carried away in the off-gas (W) - P heat input of arc (W) - P _arc electric power of arc (W) - Q_sp specific power consumption (kw Hr kg^–1) - d _w specific heat flow to wall (W m^–2) - _c degree of carbon gasification (%) - _s level of sulfur conversion into gas phase (%)     

Synthetic and kinetic studies on copper(II), nickel(II) and cobalt(III) complexes of 1,4,7,10,13-pentaazacyclohexadecane ([16]aneN5)

Summary The pentadentate macrocycle 1,4,7,10,13-penta-azacyclo-hexadecane [16]aneN₅=(3)=L} has been prepared and a variety of copper(II), nickel(II) and cobalt(III) complexes of the ligand characterised. The copper complex [CuL](ClO₄)₂, on the basis of its d-d spectrum, appears to be square pyramidal, while [NiL(H₂O)](ClO₄)₂ is octahedral. The copper(II) and nickel(II) complexes dissociate readily in acidic solution and these reactions have been studied kinetically. For the copper(II) complex, rate=k_H[complex][H⁺]² with k_H =4.8 dm⁶ mol^–2s^–1 at 25 °C and I=1.0 mol dm^–3 (NaClO₄) with H=43 kJ mol^–1 and S ₂₉₈ =–89 JK^–1 mol^–1. Dissociation rates of the copper(II) complexes increase with ring size in the order: [15]aneN₅ < [16]aneN₅ < [17]aneN₅. For the dissociation of the nickel(II) complex, rate=k_H[Complex][H⁺] with k_H=9.4×10^–3 dm³mol^–1 s^–1 at 25 °C and I =1.0 mol dm^–3 (NaClO₄) with H=71 kJ mol^–1 and S ₂₉₈ =–47 JK^–1mol^–1.The cobalt(III) complexes, [CoLCl](ClO₄)₂, [CoL(H₂O)]-(ClO₄)₃, [CoL(NO₂)](ClO₄)₂, [CoL(DMF)](ClO₄)₃ (DMF=dimethylformamide) and [CoL(O₂CH)](ClO₄)₂ have been characterised. The chloropentamine [CoCl([16]aneN₅)]²⁺ undergoes rapid base hydrolysis with k_OH=1.1× 10⁵dm³ mol^–1s^–1 at 25°C and I=0.1 mol dm^–3 (H=73 kJ mol^–1 and S ₂₉₈ =98 JK^–1 mol^–1). Rapid base hydrolysis of [CoL(NO₂)]²⁺ is also observed and the origins of these effects are considered in detail.     

Interaction of Phosphorus Iminoilides with Metal Acetates. Crystal and Molecular Structure of Cu[(2-O–)(5-NO2)C6H3N–CH=CH–+PPh3]2 · 2CHCl3

The structure of the Cu[(2-O^–)(5-NO₂)C₆H₃N–CH=CH–⁺PPh₃]₂ complex with the CuN₂O₂ coordination core of distorted square-planar geometry was established by X-ray diffraction analysis. The molecules in the crystal structure of the Cu[(2-O^–)(5-NO₂)C₆H₃N–CH=CH–⁺PPh₃]₂ · 2CHCl₃ solvate are bound via hydrogen bonds of two types, namely, C(sp ²)–H···O and C(sp ³)–H···O.     

Simultaneous Spectrophotometric Determination of Rare-Earth and Transition Elements Using Partial Least-Squares (PLS) Multivariate Calibration

A spectrophotometric method for the simultaneous determination of rare-earth and transition elements in synthetic superconductors, [(La_{1 – x} Eu _x )_1.82Sr_0.18CuO₄], by the use of 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) as chelating agent was developed. The influence of chemical variables affecting the reaction was studied. A partial least-squares (PLS) multivariate calibration procedure was used to assess the data obtained from several calibration solutions measured over the wavelengths range 400–700 nm. The concentration range for Cu was (1–12) × 10^–6 mol/L, while the range for the rare-earth elements La and Eu was (2–8) × 10^–6 mol/L. The relative errors in the determinations were less than 5% in most cases.     

New results in the ammonolysis of hexafluoro-cyclo-triphosphazene: Crystal structure of P3N3F5–NH–P3N3F4NH2

The reaction of hexafluoro-cyclo-triphosphazene P₃N₃F₆ with ammonia in acetonitrile has been studied. New compounds, (2-imino-2,4,4,6,6-pentafluoro-2λ⁵,4λ⁵,6λ⁵-cyclo-triphosphaza-1,3,5-trienyl)-2-amino-4,4,6,6-tetrafluoro-2λ⁵,4λ⁵,6λ⁵-cyclo-triphosphaza-1,3,5-triene, P₃N₃F₅–NH–P₃N₃F₄NH₂ (2) and cis and trans isomers of non-gem-2,4-diamino-2,4,6,6-tetrafluoro-2λ⁵,4λ⁵,6λ⁵-cyclo-triphosphaza-1,3,5-triene, P₃N₃F₄(NH₂)₂ (4, 5)_, were detected by GC/MS, and ³¹P NMR spectroscopy in reaction mixtures. X-ray diffraction analysis of P₃N₃F₅–NH–P₃N₃F₄NH₂ (2) revealed two conformational polymorphs, 2A and 2B, the latter being built up of two different conformers that were further denoted as 2B_a (the same as the single conformer in 2A) and 2B_b. The compound 2 was characterized by spectroscopic methods and its 2D potential energy surface (PES) was described by density functional theory computations depending on two dihedral angles. The calculated PES spans over 30 kJ/mol in energy including 8 local minima and all first and second order saddle points. The occurrence of the two experimentally observed conformers 2B_a and 2B_b seems to be governed by crystal packing effects.     

Characterization of europium(III) carbonate complexes in simulated groundwater by solvent extraction

The complex formation of Eu(III) by bicarbonate/carbonate ions has been studied at 0.1 M ionic strength and 25°C using synergistic solvent extraction system of 1-nitroso-2-naphthol and 1,10-phenanthroline in chloroform. Concentrations of bicarbonate (5·10^–3 to 1·10^–1 M) and carbonate (5·10^–4 to 1·10^–2 M) ions in the aqueous phase have been varied in the pH range of 8.0 to 9.1 to simulate ground and natural water compositions. Under these conditions, the following species have been identified: Eu(HCO₃)²⁺, Eu(HCO₃)₂ ⁺, Eu(CO₃)⁺ and Eu(CO₃)₂ ^–. Their conditional formation constants (log ) have been calculated as 4.77, 6.74, 6.92 and 10.42, respectively. These values suggest that the carbonate complexes of Eu(III) are highly stable.