Liquid NH3 Research Articles

Synthesis of Succinimido[3,4-b]indane and 1,2,3,4,5,6-Hexahydro-1,5-methano-3-benzazocine-2,4-dione by Sequential Alkylation and Intramolecular Arylation of Enolates Derived from N,N,N'N'-Tetramethylbutanediamides and N,N,N'N'-Tetramethylpentanediamides.

The tricyclic title compounds, 4 and 5, were synthesized by initial alkylation of the lithium monoenolates of N,N,N',N'-tetramethylbutanediamide (6) and N,N,N',N'-tetramethylpentanediamide (19) with 2-iodobenzyl chloride in liquid NH(3) at -60 degrees C to afford 2-(2-iodobenzyl)-N,N,N',N'-tetramethylbutanediamide (9) and 2-(2-iodobenzyl)-N,N,N',N'-tetramethylpentanediamide (20) in yields of 88 and 87%, respectively. Treatment of 9 with KNH(2) in liquid NH(3) resulted in formation and intramolecular arylation of the less-substituted alpha-enolate to produce trans-1,2-bis(N,N-dimethylcarboxamido)indane (10a) in 60% yield. Selective hydrolysis of 10a with aqueous Na(2)O(2) gave trans-1-(N,N-dimethylcarboxamido)indane-2-carboxylic acid (17), which was then converted to bridged succinimide 4 by transformation to trans-1-(N,N-dimethylcarboxamido)indane-2-carboxamide (10c) followed by cyclization of this mixed primary/tertiary amide by means of NaH in refluxing THF. Treatment of 20 with KNH(2) in liquid NH(3) led to intramolecular arylation and accompanying ammonolysis to afford trans-1-(N,N-dimethylcarboxamido)-1,2,3,4-tetrahydronaphthalene-3-carboxamide (21b). Conversion of 21b to 5 was similarly effected by means of NaH. Experiments designed to test the mechanistic aspects of the intramolecular arylations provided evidence for competing aryne and SET pathways.

Syntheses and Structure Determinations of Calcium Thiolates.

The exploration of synthetic methodologies toward heavy alkaline-earth chalcogenolates resulted in the preparation and structural characterization of a family of calcium thiolates, including [Ca(SC(6)F(5))(2)(py)(4)], 1 (py = pyridine), the separated ion-triple [Ca(18-crown-6)(NH(3))(3))][SMes](2).2THF, 2 (Mes = 2,4,6-tBu(3)C(6)H(2)), and the contact triple [Ca(18-crown-6)(SMes)(2)].THF, 3. Compound 1 was prepared by treating [Ca(N(SiMe(3))(2))(2)](2) with 4 equiv of HSC(6)F(5) under addition of pyridine. The thiolates 2 and 3 were synthesized by treatment of calcium metal dissolved in dry, liquid NH(3) under addition of 2 equiv of HSMes and crown ether or, alternatively, by the reduction of MesSSMes with calcium metal in dry, liquid ammonia. We also report two reaction products isolated during attempted calcium thiolate syntheses: [CaBr(4)(THF)(2)(&mgr;(2)-Li)(2)(THF)(4)], 4, isolated as the product of a salt elimination reaction between CaBr(2) and 2 equiv of [Li(THF)(n)()S-2,4,6-(i)()Pr(3)C(6)H(2)](m)(). [(NH(4))(py)(SC(6)F(5))], 5, was obtained as the sole product in the reaction of metallic calcium with HSC(6)F(5) in liquid ammonia under addition of pyridine. All compounds were characterized by single-crystal X-ray crystallography in addition to IR and NMR spectroscopy.

Nanocrystalline Aluminum Nitride and Aluminum/Gallium Nitride Nanocomposites via Transamination of [M(NMe2)3]2, M = Al, Al/Ga (1/1)

Reactions of [Al(NMe2)3]2 with NH3, mimicking the case of the related Ga-derivative, provided an Al−amide−imide precursor that was pyrolyzed to pure nanocrystalline AlN. Based on that chemistry, a mixed Al/Ga precursor system was designed to lead to the bimetallic nitride composites. A prototype study included equilibration in hexane or toluene of the dimers [M(NMe2)3]2, M = Al, Ga, which resulted in the formation of the homoleptic four-membered-ring compound (Me2N)2Al(μ-NMe2)2Ga(NMe2)2. Crystalline [M(NMe2)3]2, M = Al/Ga (1/1), obtained from this equilibration was structurally characterized. Transamination/deamination reactions carried out with liquid NH3 in the preequilibrated bimetallic system [Al(NMe2)3]2/[Ga(NMe2)3]2, Al/Ga = 1/1, resulted in the mixed M−amide−imide precursors that were converted at 700−1100 °C to aluminum/gallium nitride nanocomposite materials. The nature of these bulk nanocomposites has been elucidated by XRD, TEM/EDS, IR, and PL techniques.

Tl2Ch22-(Ch = Se and/or Te) Anions: X-ray Crystal Structures and Raman Spectra of (2,2,2-crypt-K+)2Tl2Se22-and (2,2,2-crypt-K+)2Tl2Te22-and Solution77Se,203Tl, and205Tl NMR Spectroscopic and Theoretical Studies of Tl2Ch22-, In2Se22-, and In2Te22-

The seleno- and tellurothallate(I) anions Tl2Ch22- (Ch = Se and/or Te) and the 77Se-enriched Tl2Se22- anion have been obtained by extraction of the alloys MTlCh (M = Na, K; Ch = Se, Te), KTlSe0.5Te0.5, and 77Se- enriched KTlSe in ethylenediamine and liquid NH3 and in the presence of a stoichiometric excess of 2,2,2-crypt with respect to M+. The butterfly-shaped Tl2Ch22- anions were characterized in solution by 77Se, 203Tl, and 205Tl NMR spectroscopy, Raman spectroscopy, and X-ray crystallography in (2,2,2-crypt-K+)2Tl2Ch22-. The energy-minimized structures of the Tl2Ch22- (Ch = Se and/or Te) anions were calculated by using density functional theory calculations confirming the nonplanar geometries of all three anions, which are compared with those of the presently unknown In2Ch22- (Ch = Se, Te) anions. The magnitudes of the relativistically corrected reduced coupling constants, (KTl-Ch)RC, are consistent with essentially pure p-bonded rings whereas the magnitudes of (KTl-Tl)RC suggest significant s electro...

Performance and Carcass Data of Steers Finished on Either Ammoniated or Nonammoniated Corn, Grain Sorghum, or Wheat Silage

Two-hundred eighty-eight steers were used in a 3 × 2 factorial arrangement of treatments to compare the effect of ammoniation of three forages at time of ensiling to similar silages not ammoniated but supplemented with cottonseed meal at feeding. Three trials were conducted over a 3-yr period with 96 steers used per year. In each year, there were eight steers per pen with two pens per simple treatment. Silage sources were corn, grain sorghum, and wheat. The factorial design resulted in six simple treatments: ammoniated corn silage; nonammoniated corn silage plus cottonseed meal; ammoniated grain sorghum silage; nonammoniated grain sorghum silage plus cottonseed meal; ammoniated wheat silage; and nonammoniated wheat silage plus cottonseed meal. Liquid NH3 was applied at the rate of 3.5 g/kg of fresh silage to the ammoniated silage at the time it was placed in the silo. No silage source by nitrogen source interaction was present (P>0.05). Steers fed corn silage gained (P<0.001) 0.18kg more weight daily during the feeding period than steers fed grain sorghum silage, whereas steers fed grain sorghum silage gained (P<0.001) 0.12kg more weight daily than steers fed wheat silage. Dry matter intake of steers fed grain sorghum silage was 8% higher (P<0.001) than with steers fed corn silage and 10% higher (P<0.001) than with steers fed wheat silage. There was no difference in DMI between steers fed corn silage and steers fed wheat silage. Crude protein intake of steers fed ammoniated silage was 0.96 kg/d whereas steers supplemented with cottonseed meal consumed 1.02kg CP/d. There was no difference (P>0.442) in ADG of steers fed either silage that had been treated with ammonia at ensiling or silage that received cottonseed meal supplementation. Dry matter intake was higher (P=0.019) for steers that received the silage plus cottonseed meal than steers that received ammoniated silage. Because there was no effect of treatment of N source on gain, but steers fed ammoniated silage consumed less DM, the feed efficiency for steers fed ammoniated silage was increased (P<0.001).

Reactivity studies with sodium amalgams

In the course of systematic studies covering various aspects of the reactivity of alkali metal amalgams we report here about first results on the behaviour of selected sodium amalgams in liquid ammonia. Starting from the most alkali metal rich amalgam Na 3Hg one can show that a stepwise extraction of sodium via Na 3Hg 2 and NaHg takes place resulting in the final formation of insoluble NaHg 2. We discuss how the stepwise extraction of sodium can be correlated to the degree of ‘condensation’ of mercury atoms to Hg n clusters in the sense of a topochemical reaction. Starting from pure Na 3Hg (isolated Hg atoms in a matrix of Na atoms) the successive formation of Na 3Hg 2 (isolated square Hg 4 clusters in a matrix of Na atoms), NaHg (one-dimensional zigzag chains of condensed Hg 4 rectangles in a matrix of Na atoms) and NaHg 2 (extended three-dimensional connection of Hg 4 rectangles) can be traced by X-ray powder methods. NaHg 2 and NaHg 4 are insoluble in liquid NH 3.

Reactivity of ytterbium in liquid ammonia

A solution of metallic ytterbium in liquid ammonia reacts readily with various carbonyl complexes of metals to form the corresponding lanthanide carbonylmetallates. The reaction of an excess of Yb in liquid NH3 with [CpFe(CO)2]2 gave (THF)4Yb[Fe(CO)2Cp]2 in 42% yield. It was suggested that the resulting complex contains two equivalent Yb−Fe bonds.

Compatibility of Various Carbanion Nucleophiles with Heteroaromatic Nucleophilic Substitution by the SRN1 Mechanism

Carbanions generated from 2,4,4-trimethyl-2-oxazoline (1a), 2-benzyl-4,4-dimethyl-2-oxazoline (1b), 2,4-dimethylthiazole (13a), 2-benzyl-4-methylthiazole (13b), N,N-dimethylacetamide (17a), tert-butyl acetate (17b), ethyl phenylacetate (17c), N-methyl-N-phenyl-2-butenamide (22), tert-butyl 3-butenoate (25), and dimethyl methylphosphonate (29a) by means of KNH2 in liquid NH3 all reacted with 2-bromopyridine (2) via photoassisted reactions that exhibited characteristics of the SRN1 mechanism. Similar results were obtained in reactions of these carbanions with other substrates, including 2-chloroquinoline (6), iodobenzene (9), bromobenzene (10), and bromomesitylene (11).

Nitrogen fertilizers promote denitrification

A laboratory study was conducted to compare the effects of different N fertilizers on emission of N2 and N2O during denitrification of NO3 – in waterlogged soil. Field-moist samples of Drummer silty clay loam soil (fine-silty, mixed, mesic Typic Haplaquoll) were incubated under aerobic conditions for 0, 2, 4, 7, 14, 21, or 42 days with or without addition of unlabelled (NH4)2SO4, urea, NH4H2PO4, (NH4)2HPO4, NH4NO3 (200 or 1000 mg N kg–1 soil), or liquid anhydrous NH3 (1000 mg N kg–1 soil). The incubated soil samples were then treated with 15N-labelled KNO3 (250 mg N kg–1 soil, 73.7 atom% 15N), and incubation was carried out under waterlogged conditions for 5 days, followed by collection of atmospheric samples for 15N analyses to determine labelled N2 and N2O. Compared to samples incubated without addition of unlabelled N, all of the fertilizers promoted denitrification of 15NO3 –. Emission of labelled N2 and N2O decreased in the order: Anhydrous NH3>urea \gg (NH4)2HPO4>(NH4)2SO4≃NH4NO3≃NH4H2PO4. The highest emissions observed with anhydrous NH3 or urea coincided with the presence of NO2 –, and 15N analyses indicated that these emissions originated from NO2 – rather than NO3 –. Emissions of labelled N2 and N2O were significantly correlated with fertilizer effects on soil pH and water-soluble organic C.

Synthesis and Crystal Structure of Tricaesium Heptaphosphide–Ammonia(1/3) Cs3P7·3 NH3

AbstractRecrystallization of Cs3P7 from liquid NH3 yields the triammoniate Cs3P7·3 NH3, which loses the weakly bound NH3 of crystallization below 253 K. A low‐temperature crystal‐structure analysis shows that Cs3P7· NH3 consists of a framework of heptaphosphanortricyclane anions P and Cs+ cations with NH3 molecules completing the coordination of the cations. The framework is built from Cs3P7 layers connected by only few Cs…︁P interactions, the interlayer gap being filled by a two‐dimensional network of NH3. The Cs7P7 part of the structure completes a family of alkali‐metal‐polyphosphide substructures which range from [RbP7]2− or [CsP11]2− chains over [Cs2Pn]− layers (n = 7, 11) to now [Cs3P7] frameworks.

Study on microscopic solvation process of Li atom in ammonia clusters: photoionization and photoelectron spectroscopies of M(NH 3) n (M = Li, Li −)

Photoionization and photodetachment processes of M(NH 3) n = (M = Li and Li −) are investigated. Ionization potentials (IPs) of Li(NH 3) n (5 ⩽ n ⩽ 28) are found to decrease monotonously with increasing n and give IP(∞ as 1.47 eV, in agreement with the photoelectric threshold of liquid NH 3. Photoelectron spectra of Li −(NH 3) n ( n ⩽ 10) exhibit a rapid decrease in the Li( 2P)−Li( 2S) separation and a red-shift of the Li( 2S)−Li −( 1S) type transition with increasing n. Based on these results as well as the theoretical results on the geometrical and electronic structures, we discuss the solvation state of the Li atom in (NH 3) n relating to the solvated-electron formation.

ELECTRONIC STRUCTURE AND STABILITY OF NH4(NH3)n AND NH4(NH3)m(H2O)n

The photoionization process of NH 4( NH 3)n and NH 4( NH 3)m( H 2 O )n radicals produced by an ArF excimer laser photolysis of ammonia clusters and ammonia–water mixed clusters are examined using time-of-flight mass spectroscopy. The ionization potentials (IPs) of NH 4( NH 3)n (n=0−35) and NH 4( NH 3)m( H 2 O )n (m=0−4, n=0−3) are determined by the photoionization threshold measurements. The binding energies of NH 4( NH 3)n−1− NH 3 (n=1−6) are estimated from IPs. The results indicate that the bonding between NH 4 and NH 3 is semi-ionic. The IPs for the large ammoniated NH 4 clusters decrease with increasing n up to 35. The limiting value (n→∞) is found to be 1.33 eV, which coincides with the photoemission threshold of liquid NH 3. This feature is similar to those found recently for alkali-atom–ammonia clusters. A clear trend is found for the IPs of NH 4( NH 3)m( H 2 O )n; the clusters containing more water molecules have higher IP. This trend is ascribed to the large binding energy of [Formula: see text] comparing with that of [Formula: see text].

A low-barrier hydrogen bond in subtilisin: 1H and 15N NMR studies with peptidyl trifluoromethyl ketones.

The N delta 1 proton of His 64 forms a hydrogen bond with Asp 32, as part of the catalytic triad in serine proteases of the subtilisin family. His 64 in subtilisin has been studied by 1H and 15N NMR spectroscopy in the presence and absence of peptidyl trifluoromethyl ketones (TFMKs) that are transition state analog inhibitors. For subtilisin Carlsberg, the downfield resonance of the imidazolium N delta 1 proton is approximately 18.3 ppm and the D/H fractionation factor is 0.55 +/- 0.04 at pH 5.5 (11 degrees C), and 0.63 +/- 0.04 (5 degrees C) and 0.68 +/- 0.04 at pH 6 (11 degrees C). In the complex between subtilisin Carlsberg and Z-L-leucyl-L-leucyl-L-phenylalanyltrifluoromethyl ketone (Z-LLF-CF3) at pH values between 6.5 and 10.6, His 64 remains positively charged, and the D/H fractionation factor of its N delta 1 proton is 0.85 +/- 0.05. In the complex between a subtilisin variant from Bacillus lentus and Z-LLF-CF3, the proton resonance at 18.8 ppm is correlated with a 15N resonance at 197.6 ppm downfield from liquid NH3 with a 1JNH of 81 Hz. The chemical shifts of subtilisin complexes with peptidyl TFMKs are among the most downfield shifts reported for any protein. At pH 9.5, His 64 is neutral and the D/H fractionation factor increases to 1.2 with a chemical shift of 15.0. His 64 is positively charged in the free enzyme at low pH, the inhibitor hemiketal complex at neutral pH, and the transition state for amide bond hydrolysis. These data thus provide indirect evidence for the presence of a low-barrier hydrogen bond in the catalytic mechanism of subtilisin proteases.

Inoculants of Azospirillum brasilense: Biomass production, survival and growth promotion of Setaria italica and Zea mays

We grew Azospirillum brasilense biomass in fed-batch culture for 28 h using succinic acid as a C source and liquid NH 3 as N source. Viable cell concentration reached 1–3 × 10 10 CFU ml −1 after 28 h. Ground or granular peat, serving as carriers for the bacteria, maintained the highest number of A. brasilense compared to vermiculite, talcum powder, basalt granules or bentonite. A. brasilense viable counts declined from about 10 10 CFU g −1 peat to 10 5–10 6 CFU g −1 peat after 6 months. A pot system for evaluating the effect of A. brasilense inoculants on plant growth in greenhouses demonstrated that application of peat-carrier containing 10 8 CFU g −1 peat, significantly increased panicle length and dry weight of Setaria italica and ear and kernel weight of maize ( Zea mays L). Highest growth promotion effects on maize were observed when using A. brasilense cells containing 40% polyhydroxybutyrate (PHB) and by applying the peat inoculant 2 cm below the maize seed.

Electrochemical Synthesis of Ceramic Materials. 4. Electrophoretic Deposition of Metal Nitride Ceramic Precursors

The authors have prepared metal nitride ceramic precursors by anodic dissolution of the corresponding metal in liquid NH{sub 3} electrolyte solutions and then deposited coatings of these precursors onto n-Si substrates by electrophoresis. X-ray diffraction and electron microscopy indicate that calcination of the precursor-coated substrates yields coatings of AlN, {delta}-NbN, and Ni{sub 3}N. Precursor coatings are formed by applying fields greater than 10V/cm between electrodes in a CH{sub 3}CN suspension of the precursor. The positively charged precursor particles deposit selectively on the cathode. Subsequent calcination in flowing NH{sub 3} or Ar yields the metal nitride coating. The Ni{sub 3}N coating was prepared by calcining the precursor at 375 {degrees}C in NH{sub 3}, while the AlN and NbN precursor coatings were prepared by calcination at 1100 {degrees}C in NH{sub 3} and 800 {degrees}C in Ar, respectively. 30 refs., 4 figs.

Synthesis and crystal structure of Sr 2ZnN 2 and Ba 2ZnN 2

Ternary nitrides, Sr 2ZnN 2 and Ba 2ZnN 2, were prepared from Sr or Ba along with Zn metal using Na metal and NaN 3 as a flux and nitrogen source, respectively. The single crystals were obtained by slow cooling from 750°C. Since these compounds hydrolyze in moist air, the crystals were isolated by washing away excess Na with liquid NH 3 in an inert environment. The structures were determined by single crystal X-ray diffraction: tetragonal, space group I 4/ mmm with Z = 2, a = 3.8568(2), c = 12.935(1) Å, and R 1 = 0.049 for Sr 2ZnN 2, and a = 4.152(1), c = 13.055(3) Å, and R 1 = 0.039 for Ba 2ZnN 2. Sr 2ZnN 2 and Ba 2ZnN 2 are isostructural with Ca 2ZnN 2 (Na 2HgO 2 type) and contain linear [NZnN] 4− nitridometallate anions.

The isotope effect in the electronic structure factors of liquid NH3 and ND3

Gamma rays from a radioisotope source, 241Am, were scattered from samples of liquid light ammonia (NH3) and heavy ammonia (ND3) at temperatures of 294.5 and 284.5 K under their normal vapour pressures to determine the electronic liquid structure factors. In addition the densities of these samples were checked by the gamma ray absorption technique. From the difference between the total electronic structure factors of liquid NH3 and ND3, the difference of the r-space electronic correlation functions of the two liquids (at the same temperature) was evaluated. The observable difference is due (mainly) to quantum effects in the intermolecular electron-density correlation functions of liquid ammonia, which will be discussed.

New Tellurometalates of Gallium and Indium: K[K([18]crown‐6)]2[GaTe3] · 2CH3CN and [(NEt4)5][In3Te7] · 0.5 Et2O

The tellurometalate ions [GaTe3]3− and [In3Te7]5− have been prepared by chemical reduction of Ga2Te3 and In2 Te3, respectively, by potassium in liquid NH3 in the presence of an encapsulating ligand. The [GaTe3]3− ion is essentially trigonal planar; the [In3Te7]5− ion is cuboidal, where one corner is missing (structure shown on the right). These anions have no counterparts in S or Se chemistry.

The synthesis of tellurometalates by the reduction of binary telluride melts with potassium in liquid ammonia

The reduction of binary telluride melts with potassium in liquid ammonia in the presence of 18-Crown-6 or 2,2,2-Crypt has been employed to synthesize and precipitate tellurometalates. The method is more rapid than conventional extraction techniques and, since lower temperatures are involved, potentially unstable fragments are conserved. A melt of nominal composition CdTe3 dissolved with K and 18-Crown-6 in liquid NH3 affords [K(18-Crown-6)]4[Cd4Te12] (1) after recrystallization from CH3CN–Et2O. Compound 1 crystallizes in the triclinic space group [Formula: see text] with one formula unit in a cell of dimensions a = 12.673(1) Å, b = 13.694(3) Å, c = 14.483(3) Å, α = 117.54(2)°, β = 96.43(1)°, and γ = 100.00(1)° at 113 K. Full anisotropic refinement of the structure on Fo2 led to a value of R1 = 0.026 for those 6654 reflections having Fo2 &gt; 2σ(Fo2). The [Cd4Te12]4− anion of 1, which may be formulated as [Cd4(Te)2(Te2)2(Te3)2]4−, consists of a rectangular array of four Cd2+ centers linked by Te2−, Te2−, and Te32− ligands. As expected from the solid-state structure, the 125Te NMR spectrum of 1 in CD3CN shows four resonances at −11, −259, −548, and −1682 ppm. A melt of nominal composition PbTe2 was dissolved with K and 2,2,2-Crypt in liquid NH3 to afford [K(2,2,2-Crypt)]2[Pb2Te3]•CH3CN (2) after recrystallization from CH3CN. Compound 2 crystallizes in the triclinic space group CI1−P1 with one formula unit in a cell of dimensions a = 11.105(3) Å, b = 11.748(4) Å, c = 11.922(3) Å, α = 118.78(2)°, β = 96.52(2)°, and γ = 91.03(3)° at 113 K. Full anisotropic refinement of the structure on Fo2 led to a value of R1 of 0.074 for those 11 135 reflections having Fo2 &gt; 2σ(Fo2). The anion of 2 consists of a triangle of Te2− ligands capped above and below the plane by two Pb2+ centers to define a trigonal bipyramid. The 125Te NMR spectrum of 2 in CD3CN shows one resonance at −928 ppm (JPb–Te: 1090 Hz). Keywords: tellurometalates, liquid ammonia, synthesis, crystal structure.

An efficient route to N6 deoxyadenosine adducts of diol epoxides of carcinogenic polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons are metabolized to a wide variety of oxidized derivatives, including highly reactive diol epoxides which alkylate DNA. The reaction lacks regio- or stereospecificity but occurs primarily at the exocyclic amino groups of deoxyguanosine and deoxyadenosine. An efficient route to N 6 adducts of deoxyadenosine is described using as examples those arising from trans opening of the anti-tetrahydrodiol epoxides of naphthalene, benzo[ a]pyrene, and benzo[ c]phenanthrene. The adducts were synthesized in 50–92% yields by reaction of 6-fluoropurine 2′-deoxyriboside with aminotriols formed by trans opening of racemic dihydrodiol epoxides using liquid NH 3. The diastereomeric adducts were separated by HPLC and their absolute configurations were assigned by circular dichroism. 1H NMR studies revealed significant differences in conformation of the tetrahydroaromatic ring between the sterically unrestricted naphthalene derivative and the sterically congested derivatives of benzo[ a]pyrene and benzo[ c]phenanthrene. These differences may have a bearing on the higher carcinogenicity shown by the latter hydrocarbons. Undecadeoxyoligonucleotides bearing regio- and stereochemically defined adenine N 6- anti- trans-benzo[ a]pyrene adducts have been prepared.