Liquid Ammonia Solutions Research Articles

A Nuclear Magnetic Relaxation Study of the Dynamics of NO3− and SCN− Ions in Liquid Ammonia

Abstract A nuclear magnetic relaxation study of the rotational dynamics of nitrate and thiocyanate anions in 1 M solutions of liquid ammonia is presented. For both anions D⊥ was determined and shown to be larger than observed in aqueous solution. The rotational anisotropy of the nitrate ion was found to be temperature dependent (233—303 K). Thiocyanate ion 13C relaxation was found to be dominated by the spin rotation mechanism. The overall dynamics of both ions is shown to be less restricted in liquid ammonia compared to their dynamics in aqueous solutions.

Solvation of Copper(II) Ions in Liquid Ammonia.

X-ray absorption fine structure (XAFS) measurements have been performed at -50 degrees C on a 0.4 mol dm(-)(3) copper(II) nitrate solution in liquid ammonia. Extended X-ray absorption fine structure (EXAFS) spectroscopy was used to determine the coordination number and bond distances for the solvated copper(II) ion in solution. The equatorial ammonia nitrogens are located 2.00 Å from the copper and the axial nitrogen 2.19 Å from the copper. However, it was not possible from the EXAFS analysis alone to conclude whether there was one or two axial nitrogens. Therefore, X-ray absorption near-edge structure (XANES) spectroscopy was combined with discrete variational Xalpha (DV-Xalpha) molecular orbital calculations for a series of five- and six-coordinated models to determine the coordination number and the geometry. The experimental XANES spectrum was best reproduced by a model where the copper(II) ion is pentacoordinated in liquid ammonia in a square pyramidal geometry with the copper(II) ion lifted above the average nitrogen plane.

Reactivities and Properties of Lanthanide Catalysts Prepared by Thermal Degradation of Liquid Ammonia Solutions of Eu or Yb Metal

Abstract Studies of X-ray diffraction, Fourier-transform infrared spectra and catalytic properties of lanthanide catalysts (Eu/AC and Yb/AC) prepared by impregnation of active carbon (AC) with liquid ammonia solutions of Eu or Yb metal were carried out for the catalytic hydrogenation of ethene. The lanthanides thus deposited on AC were changed through varied steps (metal, amide, imide or nitride) by thermal treatments and simultaneously the hydrogenation activity varied markedly. Eu/AC and Yb/AC which were subjected to the evacuation treatment around 573 and 773 K, respectively, showed a high activity even at 203 K. The catalytic properties of lanthanide amide (Eu(NH2)2, Yb(NH2)2, and Yb(NH2)3) prepared separately, imide and nitride were investigated for comparison. It was concluded that imide or imide-like species formed during the thermal decomposition processes of europium(II) and ytterbium(II and III) amides to nitride at 503—573 and 423—773 K was active catalysts for Eu/AC and Yb/AC, respectively.

Preparation of active zinc by reduction of zinc chloride with sodium in liquid ammonia and its use in the barbier reaction

Active zine powder produced by reduction of anhydrous zine chloride with solution of sodium in liquid ammonia exhibits high reactivity in the Barbier type reaction both in THF and liquid ammonia solution.

Cyclization of Ethyne and Propyne over Lanthanide Catalysts Deposited from Eu or Yb Metal Solutions in Liquid Ammonia

Abstract Europium and ytterbium catalysts separated on active carbon from a solution of lanthanide metals dissolved in liquid ammonia were found to be effective for oligomerization of alkynes. Selective cyclic dimerization and trimerization of propyne and ethyne to cyclohexadiene and benzene occurred during the oligomerization, respectively, in which the active catalysts were characterized as lanthanide imides induced by the thermal treatment.

Amination and Synthesis of Some Nitronaphthyridines

Abstract3‐Nitro and 3,6‐dinitro‐1,8‐naphthyridines 1, 4 and 5 are dehydroaminated with a liquid ammonia solution of potassium permanganate to the corresponding 4‐amino‐substituted compounds 3, 8 and 9. The intermediate 4‐amino σ‐adducts 2, 6 and 7 of the nitro‐1,8‐naphthyridines are detected by 1H‐NMR spectroscopy. The syntheses of some nitro‐substituted naphthyridines are described.

Amination of 3,5‐Dinitropyridines with Liquid Ammonia/Potassium Permanganate

Abstract3,5‐Dinitropyridine and some of its derivatives are aminated with a liquid ammonia solution of potassium permanganate to the corresponding 2‐, 4‐ and 6‐ mono‐ and (or) di‐ and (or) triamino‐substituted compounds. The intermediate amino σ‐adducts of 3,5‐dinitropyridines are detected by 1H‐NMR spectroscopy. Quantum‐mechanical calculations for a few 3,5‐dinitropyridines suggest that the experimentally observed regioselectivity of the amination is a charge‐controlled process.

Physico-chemical and catalytic properties of ytterbium introduced into Y-zeolite

Ytterbium was introduced into K+-exchanged Y-zeolite (Yb/K-Y) by impregnation from a liquid ammonia solution of the metal, and the change in the chemical state of the metal with evacuation temperature was investigated by infrared (IR), X-ray absorption fine structure (XAFS) and X-ray photoelectron (XPS) spectroscopies.When ammonia was removed by brief evacuation at room temperature followed by evacuation at 333 K, the IR spectrum showed the presence of Yb amides. The amide species were observed up to 423 K. The Yb L2-edge X-ray absorption near-edge structure (XANES) spectrum showed that the Yb species exist as 16.4% Yb(II) and 83.6% Yb(III) after evacuation at 333 K. The fraction of Yb2+ increased with increasing evacuation temperature and reached 44.2% at 573 K by the decomposition of Yb(II, III) amides to Yb(II, III) imides. The fraction of Yb(III) species increased at an evacuation temperature >600 K, owing to the decomposition of Yb imides to Yb nitride with concomitant formation of hydrogen. The Yb(II) imide species catalyses the isomerization of but-1-ene and the Michael reaction of cyclopent-2-enone with dimethylmalonate, while the Yb(III) nitride species catalyses the hydrogenation of ethene.

Preparation of high-T c oxide films via flaming solvent spray

Thick films of the high-temperature superconductors YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} and Bi{sub 1.7}Pb{sub 0.3}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10} have been prepared by spraying an ignited ethanol, ethylene glycol, or liquid ammonia solution of stoichiometric amounts of the metal nitrates (or acetates) onto polycrystalline MgO. The flaming spray is mechanically forced to traverse a region directly in front of the substrates. This new method is simple and inexpensive, and eliminates the problem of substrate cooling encountered in normal spray pyrolysis methods. Since decomposition of the solvent and metal salts occurs before deposition, the resulting films are relatively free of craters and nonuniformities common with spray methods. The method can be adapted to coat large areas and irregular or nonplanar shapes (i.e., cylinders), which could have useful magnetic shielding properties. The films were characterized by XRD and show single-phase material with preferred c-axis orientation. For YBa{sub 2}Cu{sub 3}O{sub 7-x}, resistance v.s. temperature measurements show a T{sub c} onset at 90 K and a T{sub c0} at 76 K. Silver nitrate has been added to some of the solutions in an attempt to improve contact among individual grains. 21 refs., 7 figs., 2 tabs.

Polysulfonylamine: XXXV . Synthese, Röntgenstrukturanalysen und hochaufgelöste Festkörper-NMR-Spektren der ionischen Organozinn(IV)-dimesylamide [Me 3Sn(NH 3) 2][N(SO 2Me) 2] und [Me 2Sn(DMSO) 4][N(SO 2Me) 2] 2

[Me 3Sn(NH 3) 2][N(SO 2Me) 2] ( 4) was prepared by treating Me 3SnN(SO 2Me) 2 ( 1) with liquid ammonia; single crystals suitable for X-ray diffraction were grown from a solution in liquid ammonia by slow evaporation of the solvent at −42°C. [Me 2Sn(DMSO) 4]N(SO 2Me) 2] 2 ( 5) was obtained from dimethyl sulfoxide and Me 2Sn[N(SO 2Me) 2] 2 or 1 in refluxing CCl 4, the co-product in the latter case being SnMe 4. The crystallographic data at −95°C are for 4: monoclinic, space group P2 1 / c, a 650.3(2), b 1464.7(3), c 1479.6(4) pm, β 94.63(2)°, U 1.4046 nm 3, Z = 4; for 5: triclinic, space group P 1 a 818.3(2), b 986.6(2), c 1119.9(3) pm, α 79.10(2), β 77.51(2), γ 77.58(2)°, U 0.8524 nm 3, Z = 1. The structure refinement of 4 was based on 3092 reflections with F > 4σ( F) to give R = 0.018. For 5, refinement using 3579 reflections with F > 4σ( F) yielded R = 0.021. The crystals of both compounds consist of discrete (MeSO 2) 2N − anions and Me 3Sn(NH 3) 2 + or Me 2Sn(DMSO) 4 2+ cations, respectively. The structures of the anions are similar to those observed in other ionic dimesylamides. In the cation of 4, the tin atom has an axially distorted trigonal-bipyramidal environment with apical NH 3 molecules (SnN 232.8 and 238.3, Sn C 211.7−212.4 pm, NSnN 179.2, CSnC 118.1−122.1, NSnC 88.0−91.3°). The tin atom in the centrosymmetric cation of 5 displays trans-octahedral geometry with four DMSO molecules bonded through their oxygen atoms (SnC 211.4, SnO 219.9 and 221.4 pm, (OSnO) cis 88.9 and 91.1, OSnC 86.8−93.2°). The oxygen centres of the sulfoxide ligands are sp 2-hybridized with SnOS 121.8 and 123.1°, SO 154.4 and 155.4 pm. 5 is the first example of a structurally characterized tin(IV)-sulfoxide complex in which four sulfoxide ligands are coordinated to a single tin centre. 13C, 15N and 119Sn CP/MAS NMR spectra of solid 4 and 5 agree very well with the X-ray diffraction results. In both cases, the isotropic 119Sn chemical shifts'and their tensorial properties support the nearest-neighbours-environment as shown by crystallography. The slight inequivalences of the NH 3 and DMSO ligands, respectively, are mirrored in the 15N and 13C CP/MAS spectra of 4 and 5. The 119Sn CP/MAS spectrum of 4 is complicated by the simultaneous presence of scalar and quadrupolar coupling of two inequivalent 14N nuclei with 119Sn.

Regioselectivity of the Amination of Some Nitroquinoxalines by Liquid Ammonia/potassium Permanganate

Abstract5‐ and 6‐Nitroquinoxalines and some of their derivatives are aminated in a liquid ammonia solution of potassium permanganate to yield the corresponding 2‐ and/or 3‐ and/or 5‐amino compounds. Quantum‐chemical calculations are made to explain the regioselectivity of the amination reactions.

Entropy-supported ion-pair formation in liquid ammonia

The concentration dependence of the electrolytic conductance of KCI, KBr, KI, KNO3 and KSCN in solution in liquid ammonia has been recorded in the temperature range 208–238 K. Computer evaluation of the experimental data led to the ion-pair formation constants K, which increase significantly with increasing temperature. ΔH° and ΔS° for the processes were calculated from the temperature dependence of K. The ΔH° and ΔS° data demonstrated that ion-pair formation in liquid ammonia is entropy-supported, with unfavourable enthalpy.

Effect of the protogenic nature of the medium on the rate of corrosion transformations in PT3V titanium alloy

The dependence of the rate of partial electrode reactions on the protengenic nature of medium on a titanium electrode can be evaluated by comparing parameters of the electrochemical processes on the electrode in a proton dimethyl formamide (DMFA) and protogenic aqueous medium. This problem can be solved most efficiently by the rotating disk electrode method (RDE). The RDE method was used previously for examining the main cathodic and anodic partial reactions on the electrode of PT3V titanium pseudo-{alpha}-alloy in water-ammonia media of different concentration. We investigated PT3V alloys in different structural states after holding the specimens in liquid and gaseous ammonia, freon-12 and DMFA solutions with background salts.4 refs., 3 figs., 2 tabs.

Boron Nitride Powders Formed by Aerosol Decomposition of Poly(borazinylamine) Solutions

Micrometer‐sized aerosol droplets of a liquid ammonia solution of poly(borazinylamine) were formed in a nitrogen carrier gas by using an aerosol generator. The resulting droplets were thermally decomposed in a flow reactor at 1000°C. The white powder obtained was amorphous to X‐rays and spherical with particle sizes on the order of 0.5 μm. The particles at this stage were porous, and some appeared to exhibit a hollow‐shell morphology. Subsequent calcining at 1600°C yielded dense, crystalline boron nitride powder with partial sintering.

Synthesis and characterization of YBaCuO superconductors from solutions in liquid ammonia

YBa2Cu3O7−x (123) superconducting powders have been advantageously prepared from liquid ammonia solutions of nitrate, acetate, and perchlorate precursors. The synthetic techniques used include solution pyrolysis, freeze drying, and chemical solidification by reaction with a Lewis acid. Metal stoichiometry was determined by gravimetric analysis and atomic absorption spectroscopy. Phase characterization was accomplished by powder X-ray diffraction which revealed at least 98% pure 123 for some samples. Resistivity and magnetic susceptibility measurements confirm the superconducting properties of the products with critical temperatures around 90 K. Finally, chemical and superconducting properties are discussed as a function of process parameters.

Regioselectivity of the amination of some 3‐nitropyridines by liquid ammonia/potassium permanganate

Abstract3‐Nitropyridine and some of its derivatives are aminated in a liquid ammonia solution of potassium permanganate to the corresponding 2‐ and (or) 4‐ and (or) 6‐amino compounds. Quantumchemical calculations for a few 3‐nitropyridines suggest that the experimentally observed regioselectivity of the amination is controlled by Coulombic interaction.

Absorption bands of the S3- and S62- polysulfide ions in liquid-ammonia solutions

The absorption spectra of Li 2 S 6 -NH 3 solutions have been resolved at various temperatures and concentrations. It has been shown previously that in these solutions S 6 2− is not disproportionated but is in equilibrium with S 3 − . In various previous studies, S 3 − and S 6 2− were characterized by a single absorption band in the visible range at 610 and 440 nm, respectively. It is shown that the radical S 3 − also has an absorption band at 268 nm, while S 6 2− absorbs also at 330, 288, and 244 nm. The molar extinction coefficient of these bands was determined. The value of the equilibrium constant between S 6 2− and S 3 − was determined; this value confirms previous determinations

Lithium nitrate and lithium trifluoromethanesulfonate ammoniates for electrolytes in lithium batteries

The liquid ammonia solutions of lithium nitrate and lithium trifluoromethanesulfonate (triflate) have been found to be highly conductive inorganic electrolytes with low vapor pressures. The important phases of the LiNO 3 · xNH 3 solutions (1.5 < x < 3.1) and those of the LiSO 3CF 3 · yNH 3 solutions (1.5 < y < 3.5) are documented. In addition, the temperature dependence of their conductivities, their electrical stability windows, and their NH 3 vapor pressures were determined. In summary, the lithium triflate ammoniate (LiCF 3SO 3 · 2NH 3) remains a liquid down to −10 °C. It has an electroactivity range of 3.8 V and a conductivity of 0.6 × 10 −3 ω −1 cm −1 at −10 °C. The NH 3 vapor pressure is less than 1 bar at 60 °C. The lithium nitrate ammoniate (LiNO 3 · 2NH 3) has an electroactivity range of 3.5 V and a conductivity of 2.5 × 10 −2 ω −1 cm −1 at 20 °C. The freezing point of the nitrate ammoniate is between 3 °C and −10 °C depending on the stoichiometry. Its NH 3 vapor pressure remains below 1 bar up to 40 °C. In addition, Li/MnO 2 batteries were constructed and tested using the above mentioned electrolytes.

Ionic clusters in zeolites formed by interaction with sodium solutions in liquid ammonia

An alternative route for the preparation of Na 4 3+ paramagnetic clusters in Y zeolites is described involving contact of the solid with a solution of sodium in liquid ammonia. Besides the EPR signal of the cluster a second signal, likely due to be a solvated electron in the sodalitic cage, is also observed.

Spectrochemistry of solutions. Part 22. A study of the complexation of zinc(II), cadmium(II) and mercury(II) by cyanide in liquid ammonia by vibrational spectroscopy

The stepwise ligation patterns for the complexation by CN– of Zn2+, Cd2+ and Hg2+ in liquid ammonia solutions have been established from analyses of the infrared and Raman spectra of MII/CN– mixtures between 295 and 213 K. All the cyano-complexes are soluble and complexation, complete at the 4 : 1 stage for all three metal cations, proceeds by direct replacement of the solvating NH3 by CN– on tetrahedrally co-ordinated Zn2+ and Hg2+. Cyano-ligation of Cd2+ is quite different with octahedral 1 : 1 and 2 : 1 complexes, followed by a change to tetrahedral 3 : 1 and 4 : 1 complexes. There is no evidence for multinuclear complex formation, and mononuclear complexation is strong for all three metals; no uncomplexed CN– is present until the solution composition exceeds [CN–]/[MII]= 4.0:1. Stable outer-sphere complexes (or ion associates) form between the 4:1 complexes and the Na+ cocation, viz.[Na+⋯– NC-M(CN)3], and there is some evidence for similar association of the 3 : 1 complex of Hg2+, i.e.[Na+⋯–NC–M(CN)2(NH3)]. Assignments of the vsym(CN), vasym(CN) and v(M–N) stretching frequencies of the complexes are presented.