Liquid NH3 Research Articles

Giant many-body effects in liquid ammonia absorption spectrum.

In the present work, we accurately calculate the absorption spectrum of liquid ammonia up to 13 eV using many-body perturbation approach. The electronic bandgap of liquid NH3 is perfectly described as the combination of density functional theory, Coulomb-hole screened exchange, and G0W0 approximation to the electronic self-energy, yielding a direct gap (Γ → Γ) of 7.71 eV, fully consistent with the experimentally measured gap from photo-emission spectroscopy. With respect to the NH3 optical properties, the entire spectrum in particular the low lying first absorption band is extremely affected by electron-hole interactions, leading to a fundamental redistribution of spectral weights of the independent-particle spectrum. Three well separated but broad main peaks are identified at 7.0, 9.8, and 11.8 eV with steadily increasing intensities in excellent agreement with the experimental data. Furthermore, we observe a giant net blue-shift of the first absorption peak of about 1.4 eV from gaseous to liquid phase as the direct consequence of many-body effects, allowing the associated liquid ammonia absorption band exciton to delocalize and feel more effectively the repulsion effects imposed by the surrounding solvent shells. Further, the spectrum is insensitive to the coupling of resonant and anti-resonant contributions. Concerning electronic response structure of liquid NH3, it is most sensitive to excitations at energies lower than its electronic gap.

ChemInform Abstract: Crystal Structure of Ag2(μ‐SCN)2(NH3)4.

AbstractColorless crystals of the title compound are obtained by reacting solid AgSCN with anhydrous liquid NH3 (237 K, 2 weeks).

Formation mechanisms of channels on Titan through dissolution by ammonium sulfate and erosion by liquid ammonia and ethane

Data obtained from the Cassini Visual and Infrared Mapping Spectrometer (VIMS), Imaging Science Subsystem (ISS), and Synthetic Aperture Radar (SAR) instruments have revealed an array of fluvial channels on Titan's surface, often several hundreds of kilometers in length. The paucity of impact craters on Titan's surface suggests a formation by fluvial erosion into the water-ice bedrock. Additionally, at the landing site, the Huygens Probe Descent Imager and Spectral Radiometer (DISR) imaged Earth-like rounded cobbles 0.3–15cm in diameter composed of water ice, reminiscent of rounded stream clasts on Earth. In this paper we examine different fluvial features on Titan, identified by the Cassini spacecraft, and evaluate the possibilities of channel formation by dissolution of ice by a concentrated solution of ammonium sulfate, and by mechanical erosion by flow of liquid ammonia and liquid ethane. We find that chemical erosion of Titan's channels could be completed in 280 to 1100 years (all units of time in this paper are Terrestrial, not Titanian), much shorter than the period of about 84,000 years that a concentrated (NH4)2SO4-H2O solution could exist as a liquid on the Titan surface. Mechanical erosion of Titan's channels is generally a much slower process, on the order of 102 to 105 years to completion, and is also slower than mechanical erosion of a model river on Earth, averaging 103 to 104 years. The erosional sequence of the channels on Titan may have started after the formation of water-ice on the surface by the process of chemical dissolution by (NH4)2SO4-H2O, overlapping, or followed by, a period of mechanical erosion by liquid NH3. A final stage on the cooling surface of Titan might have been characterized by liquid C2H6 as an agent of mechanical erosion.

Emergence of superconductivity in (NH3)yMxMoSe2 (M: Li, Na and K).

We report syntheses of new superconducting metal-doped MoSe2 materials (MxMoSe2). The superconducting MxMoSe2 samples were prepared using a liquid NH3 technique, and can be represented as ‘(NH3)yMxMoSe2’. The Tcs of these materials were approximately 5.0 K, independent of x and the specific metal atom. X-ray diffraction patterns of (NH3)yNaxMoSe2 were recorded using polycrystalline powders. An increase in lattice constant c showed that the Na atom was intercalated between MoSe2 layers. The x-independence of c was observed in (NH3)yNaxMoSe2, indicating the formation of a stoichiometric compound in the entire x range, which is consistent with the x-independence of Tc. A metallic edge of the Fermi level was observed in the photoemission spectrum at 30 K, demonstrating its metallic character in the normal state. Doping of MoSe2 with Li and K also yielded superconductivity. Thus, MoSe2 is a promising material for designing new superconductors, as are other transition metal dichalcogenides.

ChemInform Abstract: Ammine‐Stabilized Transition‐Metal Borohydrides of Iron, Cobalt, and Chromium: Synthesis and Characterization.

Abstract[Fe(NH3)6](BH4)2 (I) and [Co(NH3)6](BH4)2 (II) as well as the solid solution [Co(NH3)6](BH4)2‐xClx (x ≈1) (III) and the bimetallic [Fe(NH3)6](Li2(BH4)4) (IV) are prepared either in anhydrous Me2S or by a metathesis reaction in liquid NH3 as the solvents which allow for the removal of formed inert metal halides.

Ammine-Stabilized Transition-Metal Borohydrides of Iron, Cobalt, and Chromium: Synthesis and Characterization.

Iron and cobalt borohydrides stabilized by ammonia (NH3), [Fe(NH3)6](BH4)2 and [Co(NH3)6](BH4)2, were synthesized along with a solid solution, [Co(NH3)6](BH4)(2-x)Cl(x) (x ∼ 1), and a bimetallic compound, [Fe(NH3)6](Li2(BH4)4). The compounds were prepared by new low-temperature, solvent-based synthesis methods, using dimethyl sulfide or liquid NH3, which allow for the removal of inert metal halides. The crystal structures were determined from synchrotron radiation powder X-ray diffraction (SR-PXD) data. [M(NH3)6](BH4)2 (M = Fe, Co) and [Co(NH3)6](BH4)(2-x)Cl(x) crystallize in the cubic crystal system, where the transition metals are octahedrally coordinated by NH3. Polymeric chains of lithium coordinated by four bridging BH4(-) anions are found in [Fe(NH3)6](Li2(BH4)4). The new compounds have high hydrogen densities of ∼14 wt % H2 and ∼140 g H2/L and release a mixture of hydrogen and NH3 gas at low temperatures, T < 80 °C. The decomposition mechanisms of the prepared compounds along with the composites [Fe(NH3)6](BH4)2·nNH3BH3 (n = 2, 4, 6) were studied by thermal analysis and in situ SR-PXD.

ChemInform Abstract: Alternative One‐Pot Synthesis of (Trifluoromethyl)phenyldiazirines from Tosyloxime Derivatives: Application for New Synthesis of Optically Pure Diazirinylphenylalanines for Photoaffinity Labeling.

AbstractDiazirines (II) are formed from tosyloxime derivatives (I) via the deprotonation of intermediate diaziridine by NH2‐ generated from liquid NH3.

Synthetic galactomannans with potent anti-HIV activity

Ring-opening polymerization of a new 1,6-anhydro disaccharide monomer, 1, 6-anhydro-2, 3-di-O-benzyl-4-O-(2′, 3′, 4′, 6′-tetra-O-benzyl-α-d-galactopyranosyl)-α-d-mannopyranose, was carried out using PF5 as a catalyst under high vacuum at −60°C to give galactose branched mannopyranan (synthetic galactomannan), 4-O-α-d-galactopyranosyl-(1→6)-α-d-mannopyranan, after debenzylation with Na in liquid NH3. The ring-opening copolymerization with 1, 6-anhydro-tri-O-benzyl-α-d-mannopyranose in various feeds was also performed to give synthetic galactomannans with various proportions of galactose branches. After sulfation, sulfated synthetic galactomannans were found to have anti-HIV activity and cytotoxicity as high and low as those of standard curdlan and dextran sulfates, respectively, which are potent anti-HIV sulfated polysaccharides with low cytotoxicity. The anti-HIV mechanism of sulfated synthetic galactomannans used by poly-l-lysine as a model peptide of the HIV surface protein was estimated by using SPR, DSL, and zeta potential measurements, revealing the electrostatic interaction between negatively charged sulfate groups and positively charged amino groups.

The reactions of TiCl3, and of UF4 with TiCl3 in liquid ammonia: unusual coordination spheres in [Ti(NH3)8]Cl3·6NH3 and [UF(NH3)8]Cl3·3.5NH3.

TiCl3 and NH3 form octaammine titanium(III) chloride ammonia (1/6), [Ti(NH3)8]Cl3·6NH3, which is the first structurally characterized octaammine complex of a transition metal. An excess of TiCl3 reacts with UF4 in liquid NH3 and forms octaammine fluorido uranium(IV) chloride ammonia (1/3.5), [UF(NH3)8]Cl3·3.5NH3. It shows a distorted threefold-capped trigonal-prismatic coordination sphere around U(IV).

ChemInform Abstract: First Polymeric Polyphosphide via Solution Chemistry — Synthesis and Crystal Structure of CsP7.

AbstractCsP7 is prepared via a solution reaction of Cs3P11 and Te (molar ratio of 2:1) in liquid NH3 (195 K, storage for several weeks at 235 K).

ChemInform Abstract: Tetraammineplatinum(II) Dichloride Ammonia Tetrasolvate.

AbstractSingle crystals of [Pt(NH3)4]Cl2·4NH3 are grown from a mixture of PtCl2 and N‐acetylglucosamine in liquid NH3 (1.

ChemInform Abstract: Tetraamminepalladium(II) Dichloride Ammonia Tetrasolvate.

AbstractSingle crystals of [Pd(NH3)4]Cl2·4NH3 are grown from a mixture of Pd(en)Cl2 and D‐(+)‐glucono‐1,5‐lactone in liquid NH3 (1.

ChemInform Abstract: [Th10(μ‐F16)(μ3‐O4) (μ4‐O4)(NH3)32] (NO3)8·19.6 NH3 — The Largest Thorium Complex from Solution Known to Date.

AbstractThe reaction of K2Th(NO3)6 and UF4 with liquid NH3 as a solvent (‐40 °C) results in planar colorless crystals of [Th10F16O8(NH3)32] (NO3)8·19.6 NH3 with O atoms derived from air moisture.

Improvement of Complete Circulation of Aqueous Solution for Urea Production Processing with Premixing

Half of the urea is produced by complete circulation of aqueous solution processing in China. The mixing between the gas and liquid is the key of the technology. This paper presents an improvement of the complete circulation of aqueous solution processing by premixing and atomizing liquid NH3 and Methylamine. And a novel atomizer was developed for the high pressure and limited space. We proposed a new model based on the two innovations and predicted the performance of the suggested processing. The modeling prediction agreed well with the experimental results. For the same urea synthesis tower structure, the conversion rate increased 3~5%. This indicates this technology is competitive to retrofit the existed units.

Corrigendum to: Process safety in using NH3 as refrigerant in Indian ice making plants: case studies followed by policy recommendations

Corrigendum to: Process safety in using NH₃ as refrigerant in Indian ice making plants: case studies followed by policy recommendations

ChemInform Abstract: Tungsten Nanoparticles from Liquid‐Ammonia‐Based Synthesis.

AbstractW nanoparticle suspensions in n‐heptane are obtained by reduction of a heptane solution of WCl6 with Na dissolved in liquid NH3 (‐50 °C) followed by evaporation of NH3 and stabilization of nanoparticles by oleylamine as surface capping agent.

ChemInform Abstract: Preparation via the Polymer Route and Photoluminescence Properties of CeSi3N5.

AbstractThe title compound is prepared via a one‐pot liquid‐phase polymer route based on a reaction between SiCl4 and a liquid NH3 suspension of Ce[N(Tms)2]3 in hexane followed by solvent and NH4Cl removal.

15N chemical shift referencing in solid state NMR

Solid-state NMR spectroscopy has much advanced during the last decade and provides a multitude of data that can be used for high-resolution structure determination of biomolecules, polymers, inorganic compounds or macromolecules. In some cases the chemical shift referencing has become a limiting factor to the precision of the structure calculations and we have therefore evaluated a number of methods used in proton-decoupled 15N solid-state NMR spectroscopy. For 13C solid-state NMR spectroscopy adamantane is generally accepted as an external standard, but to calibrate the 15N chemical shift scale several standards are in use. As a consequence the published chemical shift values exhibit considerable differences (up to 22ppm). In this paper we report the 15N chemical shift of several commonly used references compounds in order to allow for comparison and recalibration of published data and future work. We show that 15NH4Cl in its powdered form (at 39.3ppm with respect to liquid NH3) is a suitable external reference as it produces narrow lines when compared to other reference compounds and at the same time allows for the set-up of cross-polarization NMR experiments. The compound is suitable to calibrate magic angle spinning and static NMR experiments. Finally the temperature variation of 15NH4Cl chemical shift is reported.

ChemInform Abstract: [Bi4]6‐ — The Zintl Anion with the Highest Charge per Atom Obtained from Solution.

AbstractDark blue crystals of K6[Bi4](NH3)8 are obtained from a solution of the Zintl phase KBi in liquid NH3 in the presence of 18‐crown‐6 (‐70 °C, 3 months; 20‐30% yield).

ChemInform Abstract: Anionogenic Mixed Valency in KxBa1‐xO2‐δ.

AbstractThe solid solution series KxBa1‐xO2‐δ (x &lt; 0.41) is synthesized from stoichiometric amounts of Ba(NO3)2 and KO2 in liquid NH3 (‐40 to ‐60 °C, 30 min).