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Cas Database

7664-41-7

7664-41-7

Identification

  • Product Name:Ammonia

  • CAS Number: 7664-41-7

  • EINECS:231-635-3

  • Molecular Weight:17.0305

  • Molecular Formula: NH3

  • HS Code:2814100000

  • Mol File:7664-41-7.mol

Synonyms:Ammoniagas;Ammonia-14N;Nitro-Sil;R 717;R 717 (ammonia);Refrigerent R717;Spiritof Hartshorn;

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Safety information and MSDS view more

  • Pictogram(s):ToxicT; DangerousN

  • Hazard Codes: F:Flammable;

  • Signal Word:Danger

  • Hazard Statement:H221 Flammable gasH314 Causes severe skin burns and eye damage H331 Toxic if inhaled H400 Very toxic to aquatic life

  • First-aid measures: General adviceConsult a physician. Show this safety data sheet to the doctor in attendance.If inhaled Fresh air, rest. Half-upright position. Administration of oxygen may be needed. Refer immediately for medical attention. In case of skin contact Rinse skin with plenty of water or shower for at least 15 minutes. ON FROSTBITE: rinse with plenty of water, do NOT remove clothes. Refer immediately for medical attention . In case of eye contact Rinse with plenty of water for several minutes (remove contact lenses if easily possible). Refer immediately for medical attention. If swallowed Never give anything by mouth to an unconscious person. Rinse mouth with water. Consult a physician. Excerpt from ERG Guide 125 [Gases - Corrosive]: TOXIC; may be fatal if inhaled, ingested or absorbed through skin. Vapors are extremely irritating and corrosive. Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control may cause pollution. (ERG, 2016)Vapors cause irritation of eyes and respiratory tract. Liquid will burn skin and eyes. Poisonous; may be fatal if inhaled. Contact may cause burns to skin and eyes. Contact with liquid may cause frostbite. (EPA, 1998)Excerpt from ERG Guide 154 [Substances - Toxic and/or Corrosive (Non-Combustible)]: TOXIC; inhalation, ingestion or skin contact with material may cause severe injury or death. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution. (ERG, 2016) Inhalation of ammonia gas: Observe carefully for signs of progressive upper airway obstruction, and intubate early if necessary. Administer humidified supplemental oxygen and bronchodilators for wheezing. Treat noncardiogenic pulmonary edema if it occurs. Asymptomatic or mildly symptomatic patients may be discharged after a brief observation period. Ingestion of aqueous solution: If a solution of 10% or greater has been ingested or if ther are any symptoms of corrosive injury (dysphagia, drooling, or pain), perform flexible endoscopy to evaluate for serious esophageal or gastric injury. Obtain chest and abdominal radiograph to look for mediastinal or abdominal free air, which suggests esophageal or gastrointestinal perforation. Eye exposure: After eye irrigation, perform fluorescein examination and refer the patient to an ophthalmologist if there is evidence of corneal injury.

  • Fire-fighting measures: Suitable extinguishing media Suitable extinguishing media: Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide. Excerpt from ERG Guide 125 [Gases - Corrosive]: Some may burn but none ignite readily. Vapors from liquefied gas are initially heavier than air and spread along ground. Some of these materials may react violently with water. Cylinders exposed to fire may vent and release toxic and/or corrosive gas through pressure relief devices. Containers may explode when heated. Ruptured cylinders may rocket. For UN1005: Anhydrous ammonia, at high concentrations in confined spaces, presents a flammability risk if a source of ignition is introduced. (ERG, 2016)Mixing of ammonia with several chemicals can cause severe fire hazards and/or explosions. Ammonia in container may explode in heat of fire. Incompatible with many materials including silver and gold salts, halogens, alkali metals, nitrogen trichloride, potassium chlorate, chromyl chloride, oxygen halides, acid vapors, azides, ethylene oxide, picric acid and many other chemicals. Mixing with other chemicals and water. Hazardous polymerization may not occur. (EPA, 1998)Excerpt from ERG Guide 154 [Substances - Toxic and/or Corrosive (Non-Combustible)]: Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated. For electric vehicles or equipment, ERG Guide 147 (lithium ion batteries) or ERG Guide 138 (sodium batteries) should also be consulted. (ERG, 2016) Wear self-contained breathing apparatus for firefighting if necessary.

  • Accidental release measures: Use personal protective equipment. Avoid dust formation. Avoid breathing vapours, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas. Avoid breathing dust. For personal protection see section 8. Evacuate danger area! Consult an expert! Personal protection: gas-tight chemical protection suit including self-contained breathing apparatus. Ventilation. Shut off cylinder if possible. Isolate the area until the gas has dispersed. Remove gas with fine water spray. NEVER direct water jet on liquid. ACCIDENTAL RELEASE MEASURES: Personal precautions, protective equipment and emergency procedures: Wear respiratory protection. Avoid breathing vapors, mist or gas. Ensure adequate ventilation. Remove all sources of ignition. Evacuate personnel to safe areas. Beware of vapors accumulating to form explosive concentrations. Vapors can accumulate in low areas. Environmental precautions: Prevent further leakage or spillage if safe to do so. Do not let product enter drains. Discharge into the environment must be avoided. Methods and materials for containment and cleaning up: Contain spillage, and then collect with an electrically protected vacuum cleaner or by wet-brushing and place in container for disposal according to local regulations.

  • Handling and storage: Avoid contact with skin and eyes. Avoid formation of dust and aerosols. Avoid exposure - obtain special instructions before use.Provide appropriate exhaust ventilation at places where dust is formed. For precautions see section 2.2. Fireproof. Separated from oxidants, acids and halogens. Cool. Keep in a well-ventilated room.Keep container tightly closed in a dry and well-ventilated place. Contents under pressure. Storage class (TRGS 510): Gases

  • Exposure controls/personal protection:Occupational Exposure limit valuesRecommended Exposure Limit: 10-hour Time-Weighted Avearge: 25 ppm (18 mg/cu m).Recommended Exposure Limit: 15-minute Short-Term Exposure Limit: 35 ppm (27 mg/cu m).Biological limit values Handle in accordance with good industrial hygiene and safety practice. Wash hands before breaks and at the end of workday. Eye/face protection Safety glasses with side-shields conforming to EN166. Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU). Skin protection Wear impervious clothing. The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace. Handle with gloves. Gloves must be inspected prior to use. Use proper glove removal technique(without touching glove's outer surface) to avoid skin contact with this product. Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. Wash and dry hands. The selected protective gloves have to satisfy the specifications of EU Directive 89/686/EEC and the standard EN 374 derived from it. Respiratory protection Wear dust mask when handling large quantities. Thermal hazards

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Relevant articles and documentsAll total 458 Articles be found

Modulating Single-Atom Palladium Sites with Copper for Enhanced Ambient Ammonia Electrosynthesis

Cheng, Hao,Han, Lili,Lin, Lili,Liu, Xijun,Luo, Jun,Ou, Pengfei,Ren, Zhouhong,Rui, Ning,Song, Jun,Sun, Jiaqiang,Xin, Huolin L.,Zhuo, Longchao

, p. 345 - 350 (2021)

The electrochemical reduction of N2 to NH3 is emerging as a promising alternative for sustainable and distributed production of NH3. However, the development has been impeded by difficulties in N2 adsorption, protonation of *NN, and inhibition of competing hydrogen evolution. To address the issues, we design a catalyst with diatomic Pd-Cu sites on N-doped carbon by modulation of single-atom Pd sites with Cu. The introduction of Cu not only shifts the partial density of states of Pd toward the Fermi level but also promotes the d-2π* coupling between Pd and adsorbed N2, leading to enhanced chemisorption and activated protonation of N2, and suppressed hydrogen evolution. As a result, the catalyst achieves a high Faradaic efficiency of 24.8±0.8 % and a desirable NH3 yield rate of 69.2±2.5 μg h?1 mgcat.?1, far outperforming the individual single-atom Pd catalyst. This work paves a pathway of engineering single-atom-based electrocatalysts for enhanced ammonia electrosynthesis.

House, J. E. Jr.,Kemper, K. A.

, p. 1855 - 1858 (1987)

Efficient electrochemical reduction of nitrate to nitrogen on tin cathode at very high cathodic potentials

Katsounaros,Ipsakis,Polatides,Kyriacou

, p. 1329 - 1338 (2006)

The electrochemical reduction of nitrate on tin cathode at very high cathodic potentials was studied in 0.1 M K2SO4, 0.05 M KNO3 electrolyte. A high rate of nitrate reduction (0.206 mmol min-1 cm-2) and a high selectivity (%S) of nitrogen (92%) was obtained at -2.9 V versus Ag/AgCl. The main by-products were ammonia (8%) and nitrite (2O and traces of NO were also detected. As the cathodic potential increases, the %S of nitrogen increases, while that of ammonia displays a maximum at -2.2 V. The %S of nitrite decreases from 65% at -1.8 V to A cathodic corrosion of tin was observed, which was more intensive in the absence of nitrate. At potentials more negative than -2.4 V, small amounts of tin hydride were detected.

Murphy, W. Roger, Jr.,Takeuchi, Kenneth J.,Meyer, Thomas J.

, p. 5817 - 5819 (1982)

Synthesis, Pharmacological, and Biological Evaluation of 2-Furoyl-Based MIF-1 Peptidomimetics and the Development of a General-Purpose Model for Allosteric Modulators (ALLOPTML)

Sampaio-Dias, Ivo E.,Rodríguez-Borges, José E.,Yá?ez-Pérez, Víctor,Arrasate, Sonia,Llorente, Javier,Brea, José M.,Bediaga, Harbil,Vin?, Dolores,Loza, Mariá Isabel,Caaman?, Olga,Garciá-Mera, Xerardo,González-Diáz, Humberto

, p. 203 - 215 (2021)

This work describes the synthesis and pharmacological evaluation of 2-furoyl-based Melanostatin (MIF-1) peptidomimetics as dopamine D2 modulating agents. Eight novel peptidomimetics were tested for their ability to enhance the maximal effect of tritiated N-propylapomorphine ([3H]-NPA) at D2 receptors (D2R). In this series, 2-furoyl-l-leucylglycinamide (6a) produced a statistically significant increase in the maximal [3H]-NPA response at 10 pM (11 ± 1%), comparable to the effect of MIF-1 (18 ± 9%) at the same concentration. This result supports previous evidence that the replacement of proline residue by heteroaromatic scaffolds are tolerated at the allosteric binding site of MIF-1. Biological assays performed for peptidomimetic 6a using cortex neurons from 19-day-old Wistar-Kyoto rat embryos suggest that 6a displays no neurotoxicity up to 100 μM. Overall, the pharmacological and toxicological profile and the structural simplicity of 6a makes this peptidomimetic a potential lead compound for further development and optimization, paving the way for the development of novel modulating agents of D2R suitable for the treatment of CNS-related diseases. Additionally, the pharmacological and biological data herein reported, along with >20a000 outcomes of preclinical assays, was used to seek a general model to predict the allosteric modulatory potential of molecular candidates for a myriad of target receptors, organisms, cell lines, and biological activity parameters based on perturbation theory (PT) ideas and machine learning (ML) techniques, abbreviated as ALLOPTML. By doing so, ALLOPTML shows high specificity Sp = 89.2/89.4%, sensitivity Sn = 71.3/72.2%, and accuracy Ac = 86.1%/86.4% in training/validation series, respectively. To the best of our knowledge, ALLOPTML is the first general-purpose chemoinformatic tool using a PTML-based model for the multioutput and multicondition prediction of allosteric compounds, which is expected to save both time and resources during the early drug discovery of allosteric modulators.

New insight into hydroxyl-mediated NH3 formation on the Rh-CeO2 catalyst surface during catalytic reduction of NO by CO

Wang, Chengxiong,Xia, Wenzheng,Zhao, Yunkun

, p. 1399 - 1405 (2017)

Vibrational IR spectra and light-off investigations show that NH3 forms via the “hydrogen down” reaction of adsorbed CO and NO with hydroxyl groups on a CeO2 support during the catalytic reduction of NO by CO. The presence of water in the reaction stream results in a significant increase in NH3 selectivity. This result is due to water-induced hydroxylation promoting NH3 formation and the competitive adsorption of H2O and NO at the same sites, which inhibits the reactivity of NO reduction by NH3.

Cerium and tin oxides anchored onto reduced graphene oxide for selective catalytic reduction of NO with NH3 at low temperatures

Wang, Yanli,Kang, Ying,Ge, Meng,Zhang, Xiu,Zhan, Liang

, p. 36383 - 36391 (2018)

A series of cerium and tin oxides anchored on reduced graphene oxide (CeO2-SnOx/rGO) catalysts are synthesized using a hydrothermal method and their catalytic activities are investigated by selective catalytic reduction (SCR) of NO with NH3 in the temperature range of 120-280 °C. The results indicate that the CeO2-SnOx/rGO catalyst shows high SCR activity and high selectivity to N2 in the temperature range of 120-280 °C. The catalyst with a mass ratio of (Ce + Sn)/GO = 3.9 exhibits NO conversion of about 86% at 160 °C, above 97% NO conversion at temperatures of 200-280 °C and higher than 95% N2 selectivity at 120-280 °C. In addition, the catalyst presents a certain SO2 resistance. It is found that the highly dispersed CeO2 nanoparticles are deposited on the surface of rGO nanosheets, because of the incorporation of Sn4+ into the lattice of CeO2. The mesoporous structures of the CeO2-SnOx/rGO catalyst provides a large specific surface area and more active sites for facilitating the adsorption of reactant species, leading to high SCR activity. More importantly, the synergistic interaction between cerium and tin oxides is responsible for the excellent SCR activity, which results in a higher ratio of Ce3+/(Ce3+ + Ce4+), higher concentrations of surface chemisorbed oxygen and oxygen vacancies, more strong acid sites and stronger acid strength on the surface of the CeSn(3.9)/rGO catalyst.

Reduction of nitrate and nitrite ions over Ni-ZnS photocatalyst under visible light irradiation in the presence of a sacrificial reagent

Hamanoi, Osamu,Kudo, Akihiko

, p. 838 - 839 (2002)

Ni-doped ZnS photocatalysts (Zn0.999Ni0.001S) with a 2.4 eV energy gap showed activities for the reduction of nitrate and nitrite ions to nitrite, ammonia, and dinitrogen under visible light irradiation (λ > 420 nm) in the presence of methanol as a reducing reagent. The reduction of nitrate ions competed with that of water to form dihydrogen. The concentration of nitrate ions and loading a platinum cocatalyst affected the selectivity for the reduction products of nitrate ions.

Boosted electrocatalytic N2 reduction on fluorine-doped SnO2 mesoporous nanosheets

Liu, Ya-Ping,Li, Yu-Biao,Zhang, Hu,Chu, Ke

, p. 10424 - 10431 (2019)

The development of highly active and durable electrocatalysts toward the N2 reduction reaction (NRR) holds a key to ambient electrocatalytic NH3 synthesis. Herein, fluorine (F)-doped SnO2 mesoporous nanosheets on carbon cloth (F-SnO2/CC) were developed as an efficient NRR electrocatalyst. Benefiting from the combined structural advantages of mesoporous nanosheet structure and F-doping, the F-SnO2/CC exhibited high NRR activity with an NH3 yield of 19.3 μg h-1 mg-1 and a Faradaic efficiency of 8.6% at-0.45 V (vs RHE) in 0.1 M Na2SO4, comparable or even superior to those of most reported NRR electrocatalysts. Density functional theory calculations revealed that the F-doping could readily tailor the electronic structure of SnO2 to render it with improved conductivity and increased positive charge on active Sn sites, leading to the lowered reaction energy barriers and boosted NRR activity.

Built-in Electric Field Triggered Interfacial Accumulation Effect for Efficient Nitrate Removal at Ultra-Low Concentration and Electroreduction to Ammonia

Sun, Wu-Ji,Ji, Hao-Qing,Li, Lan-Xin,Zhang, Hao-Yu,Wang, Zhen-Kang,He, Jing-Hui,Lu, Jian-Mei

, p. 22933 - 22939 (2021)

A built-in electric field in electrocatalyst can significantly accumulate higher concentration of NO3? ions near electrocatalyst surface region, thus facilitating mass transfer for efficient nitrate removal at ultra-low concentration and electroreduction reaction (NO3RR). A model electrocatalyst is created by stacking CuCl (111) and rutile TiO2 (110) layers together, in which a built-in electric field induced from the electron transfer from TiO2 to CuCl (CuCl_BEF) is successfully formed. This built-in electric field effectively triggers interfacial accumulation of NO3? ions around the electrocatalyst. The electric field also raises the energy of key reaction intermediate *NO to lower the energy barrier of the rate determining step. A NH3 product selectivity of 98.6 %, a low NO2? production of ?1 is achieved, which are all the best among studies reported at 100 mg L?1 of nitrate concentration to date.

NO + H2 reaction on Pt(100). Steady state and oscillatory kinetics

Slinko, M.,Fink, T.,Loeher, T.,Madden, H. H.,Lombardo, S. J.,et al.

, p. 157 - 170 (1992)

The reaction of NO + H2 on Pt(100) was studied in the 10-6 mbar range between 300 and 800 K with mass spectrometry, work-function measurements, and video LEED. Both multiple steady states and kinetic oscillations were found. The principal reaction products were N2, H2O and NH3, and the activity and selectivity of the reaction were seen to depend on the partial pressure ratio pH(2)/pNO, on the surface temperature, and on the degree of surface reconstruction. Whereas the 1 × 1 surface of Pt was active for both N2 and NH3 formation, a well-annealed hex phase exhibited a low catalytic activity. The occurrence of defects during the 1 × 1 hex transition was shown to lead to enhanced N2 formation. At low pH(2)/pNO ratios, N2 formation was favored, while for large pH(2)/pNO ratios NH3 production was enhanced. Kinetic oscillations, as determined from variations in the N2, H2O and work-function signals, were found between 430 and 445 K.

Gland, John L.,Kollin, Edward B.

, p. 349 - 354 (1981)

Putting ammonia into a chemically opened fullerene

Whitener Jr., Keith E.,Frunze, Michael,Iwamatsu, Sho-Ichi,Murata, Shizuaki,Cross, R. James,Saunders, Martin

, p. 13996 - 13999 (2008)

We put ammonia into an open-cage fullerene with a 20-membered ring (1) as the orifice and examined the properties of the complex using NMR and MALDI-TOF mass spectroscopy. The proton NMR shows a broad resonance corresponding to endohedral NH3 at δH = -12.3 ppm relative to TMS. This resonance was seen to narrow when a 14N decoupling frequency was applied. MALDI spectroscopy confirmed the presence of both 1 (m/z = 1172) and 1 + NH3 (m/z = 1189), and integrated intensities of MALDI peak trains and NMR resonances indicate an incorporation fraction of 35-50% under our experimental conditions. NMR observations showed a diminished incorporation fraction after 6 months of storage at -10°C, which indicates that ammonia slowly escapes from the open-cage fullerene.

McCoy, R. E.

, p. 1447 - 1448 (1954)

Catalytic Cleavage of the Amide Bond in Urea Using a Cobalt(III) Amino-Based Complex

Uprety, Bhawna,Arderne, Charmaine,Bernal, Ivan

, p. 5058 - 5067 (2018)

The urease mimetic activity of CoIII amine complexes with respect to cleavage of urea was explored using SCXRD and spectroscopic techniques. The reaction of [CoIII(tren)Cl2]Cl [tren = tris(2-aminoethyl)amine] with urea results in the formation of an isocyanato complex {[CoIII(tren)(NH3)(NCO)]Cl2} and ammonia, following the cleavage of the amide bond. The reaction progress and the subsequent formation of cleavage products were confirmed by SCXRD analysis of the reactants as well as the products obtained during the reaction. The reaction was found to be pH and temperature dependent, and the reaction conditions were optimized to maximize conversion. The reaction kinetics was followed spectroscopically (1H NMR and UV/Vis), following the decrease in urea concentration or the increase in pH succeeding ammonia formation. A detailed kinetic study revealed an overall second order rate law and kobs was found to be 3.89 × 10–4 m–1 s–1.

Ruthenium(III)-aminopolycarboxylato complexes active for the reduction of the N-N bond of hydrazine and phenylhydrazine in aqueous acidic media

Prakash, Raju,Ramachandraiah, Gadde

, p. 85 - 92 (2000)

Interactions of hydrazines N2H4X+ (X = H or Ph) with tri-, tetra- and penta-chelated ruthenium(III)-aminopolycarboxylic acid complexes giving the respective monomeric hydrazinium (RuIII-N2H4X+) adducts have been investigated by potentiometry, spectrophotometry and voltammetry in aqueous acidic solution at 25°C. The deprotonation and metal hydrolysis constants of the complexes and their N2H4X+ adducts in 0.1 M Na2SO4 solution were determined. At pH 2.8, the complexes exhibited a quasi-reversible one-electron reduction wave of RuIII→ RuII in sampled dc in the potential range between -0.16 and -0.37 V vs. SCE, while their hydrazinium adducts obtained in situ by adding an excess of N2H4X+ showed an additional two-electron reduction wave assigned to RuIII-N2H4X+ → RuI-N2H4X+ in the potential range of -0.02 to -0.35 V vs. SCE. The species RuI-N2H4X+ on successive decomposition and hydrolysis give one mole of each of NH3, NH2X and ruthenium(III) species. Further, the RuIII-N2H4X+ complexes have been used as electro-catalysts for the reduction of N2H4X+ to NH3 and NH2X at a mercury pool cathode in acidic solutions of pH 1.9 and 2.8. The quantity of ammonia produced in all cases is linear with time. The E1/2 of RuIII-N2H4X+ → RuI-N2H4X+ and the turnover number are correlated with the sigma basicity (∑pKa) of the aminopolycarboxylic acids and the results are discussed in terms of the hydrolytic tendency of the metal, the number of co-ordinating groups and the steric repulsion caused by the increase in size of the aminopolycarboxylic acid. The Royal Society of Chemistry 2000.

Turrentine, J. W.

, p. 803 (1911)

Franklin, E. C.

, p. 820 - 851 (1905)

Vanadia directed synthesis of anatase TiO2 truncated bipyramids with preferential exposure of the reactive {001} facet

Shi, Quanquan,Li, Yong,Zhan, Ensheng,Ta, Na,Shen, Wenjie

, p. 3376 - 3382 (2015)

Anatase TiO2 truncated bipyramids that dominantly exposed the reactive {001} facet were hydrothermally synthesized using vanadia as the structure-directing agent. The exposed fraction of the {001} facet approached 53% upon adjusting the V/Ti mo

NiMn mixed oxides with enhanced low-temperature deNOx performance: Insight into the coordinated decoration of MnOx by NiO phase via glycine combustion method

Du, Yali,Hou, Benhui,Liu, Jiangning,Liu, Lili,Wu, Xu,Xie, Xianmei

, (2021)

Herein, a facile glycine combustion method was utilized to prepare a series of Ni and Mn based single/double metal oxides, which were evaluated as catalysts for low temperature selective catalytic reduction of NO with NH3. The NiMn-T samples presented superior catalytic performance especially for NiMn-400, with ~100 % NOx conversion, >85 % N2 selectivity within 90-300 °C, and better SO2 resistance. The superior catalytic activity might be related to the coordination of Ni and Mn, which afforded higher Mn4+/Mnn+ ratio, larger SBET, more suitable acid site amounts and redox capacity. The improved SO2 resistance of NiMn-400 catalyst can be ascribed to the less ammonium (bi)sulfate deposition and metal sulfation. In-situ DRIFTS revealed that the Ni doping could deliver more reactive species (NH2, monodentate nitrite, bidentate nitrate), and the surface acidity is less affected by SO2, which can account for the enhanced low temperature activity and SO2 resistance of the NiMn-400 catalyst.

Grubb

, p. 600 (1923)

Conversions of coordinated ligands by reducing thermolysis of some double complex compounds

Pechenyuk,Domonov,Avedisyan,Ikorskii

, p. 734 - 738 (2010)

Thermal decomposition of binary complexes [M(NH3) k]x[M'Ln]y (M = Ni, Co; M' = Fe, Cr, Cu; L = CN-, SCN-, C2O42 -) in a hydrogen atmosphere showed conversion of coordinated CN-groups into ammonia and hydrocarbons; SCN-into ammonia, hydrogen sulfide, and hydrocarbons; and C 2O42 - into hydrocarbons and CO2. In all cases, methane prevails in the resulting hydrocarbons; ethylene is the second in relative yield, which however strongly depends on the temperature and combination of the central ions of double complex salts. The yield of ethylene is especially high from the reduction of Co-Fe complexes at 350°C, Co 4-Fe3 complexes at 500°C, Ni3-Fe 2 and Ni3-Cr2 complexes at 350°C. The observed conversions of coordinated groups can be interpreted as arising from the catalytic effect caused by the reduced forms of the central atoms in the binary complexes to the interaction of ligands with hydrogen. Pleiades Publishing, Ltd., 2010.

Browne, A. W.,Hoel, A. B.

, p. 2116 (1922)

Kirk, R. E.,Browne, A. W.

, p. 337 (1928)

NH3 formation from N2 and H2 mediated by molecular tri-iron complexes

Baabe, Dirk,Bontemps, Sébastien,Coppel, Yannick,Freytag, Matthias,Jones, Peter G.,Münster, Katharina,Maron, Laurent,Reiners, Matthias,Rosal, Iker del,Walter, Marc D.,Zaretzke, Marc-Kevin

, (2020)

Living systems carry out the reduction of N2 to ammonia (NH3) through a series of protonation and electron transfer steps under ambient conditions using the enzyme nitrogenase. In the chemical industry, the Haber–Bosch process hydrogenates N2 but requires high temperatures and pressures. Both processes rely on iron-based catalysts, but molecular iron complexes that promote the formation of NH3 on addition of H2 to N2 have remained difficult to devise. Here, we isolate the tri(iron)bis(nitrido) complex [(Cp′Fe)3(μ3-N)2] (in which Cp′ = η5-1,2,4-(Me3C)3C5H2), which is prepared by reduction of [Cp′Fe(μ-I)]2 under an N2 atmosphere and comprises three iron centres bridged by two μ3-nitrido ligands. In solution, this complex reacts with H2 at ambient temperature (22 °C) and low pressure (1 or 4 bar) to form NH3. In the solid state, it is converted into the tri(iron)bis(imido) species, [(Cp′Fe)3(μ3-NH)2], by addition of H2 (10 bar) through an unusual solid–gas, single-crystal-to-single-crystal transformation. In solution, [(Cp′Fe)3(μ3-NH)2] further reacts with H2 or H+ to form NH3. [Figure not available: see fulltext.].

Silica-Assisted Fabrication of N-doped Porous Carbon for Efficient Electrocatalytic Nitrogen Fixation

Hu, Chao,Liang, Sucen,Bai, Silin,Yang, Juan,Zhang, Xu,Qiu, Jieshan

, p. 3453 - 3458 (2020)

Here we demonstrate a silica-assisted strategy for the synthesis of N-doped porous carbon nanoparticles from zeolitic imidazolate framework precursors. As a metal-free electrocatalyst for N2 reduction to NH3 at ambient conditions, such porous carbon shows an improved catalytic performance compared with the counterpart without the assistance of silica, delivering a higher NH3 formation rate of 7.22 μg h?1 mgcat?1 and a Faradic efficiency of 7.42 % in 0.1 M HCl solution. The mesopores involved in the carbon catalyst are supposed to be responsible for the efficient electroreduction of N2.

Lee, J. Y.,Schwank, J.

, p. 207 - 215 (1986)

Infrared spectra and molecular dynamics simulations of cis-HONO isomer in an argon matrix

Talik, Tadeusz,Tokhadze, Konstantin G.,Mielke, Zofia

, p. 95 - 102 (2002)

Temperature dependent infrared spectra of cis-HONO trapped in an argon matrix are presented. All observed cis-HONO fundamental bands appear as doublets in the spectra. Both components of each doublet show reversible temperature broadening. Molecular dynamics simulations of cis-HONO trapping in an argon matrix suggest that the molecule is trapped in a one-atom substitutional cage in solid argon; no evidence of non-equivalent trapping sites was found. Experimental and theoretical results are discussed.

Adsorption and decomposition of hydrazine on Pd(100)

Dopheide,Schroeter,Zacharias

, p. 86 - 96 (1991)

The adsorption and decomposition of N2H4 on Pd(100) has been studied by measuring the sticking coefficient and by thermal desorption spectroscopy. Well-defined molecular beam dosing has been employed to limit the interaction of hydra

Ammonia formation over Pd/Al2O3 modified with cerium and barium

Adams, Emma Catherine,Skoglundh, Magnus,Gabrielsson, P?r,Laurell, Mats,Carlsson, Per-Anders

, p. 210 - 216 (2016)

We report experimental results for ammonia formation from nitric oxide and either a direct source of hydrogen or from a mixture of carbon monoxide and water over palladium based catalysts. Specifically, the addition of barium or cerium into an alumina supported palladium sample was studied. Static and transient flow reactor experiments were performed in order to identify the effects of temperature and the presence of oxygen on the activity for ammonia formation. Modification of Pd/Al2O3 with cerium proved to be beneficial for the activity due mainly to its enhancement of the water-gas-shift reaction, thus providing a higher availability of hydrogen for ammonia formation, but also because it remains active in the presence of slightly oxidizing global conditions when hydrogen is provided directly to the feed. Although the modification of Pd/Al2O3 with barium did not affect the ammonia formation during static conditions, the activity during lean/rich cycling increased. This is important for applications of passive selective catalytic reduction.

Relayed hyperpolarization from: Para -hydrogen improves the NMR detectability of alcohols

Rayner, Peter J.,Tickner, Ben. J.,Iali, Wissam,Fekete, Marianna,Robinson, Alastair D.,Duckett, Simon B.

, p. 7709 - 7717 (2019)

The detection of alcohols by magnetic resonance techniques is important for their characterization and the monitoring of chemical change. Hyperpolarization processes can make previously inpractical measurements, such as the determination of low concentration intermediates, possible. Here, we investigate the SABRE-Relay method in order to define its key characteristics and improve the resulting 1H NMR signal gains which subsequently approach 103 per proton. We identify optimal amine proton transfer agents for SABRE-Relay and show how catalyst structure influences the outcome. The breadth of the method is revealed by expansion to more complex alcohols and the polarization of heteronuclei.

Intramolecular Hydrogen Bonding Facilitates Electrocatalytic Reduction of Nitrite in Aqueous Solutions

Xu, Song,Kwon, Hyuk-Yong,Ashley, Daniel C.,Chen, Chun-Hsing,Jakubikova, Elena,Smith, Jeremy M.

, p. 9443 - 9451 (2019)

This work reports a combined experimental and computational mechanistic investigation into the electrocatalytic reduction of nitrite to ammonia by a cobalt macrocycle in an aqueous solution. In the presence of a nitrite substrate, the Co(III) precatalyst, [Co(DIM)(NO2)2]+ (DIM = 2,3-dimethyl-1,4,8,11-tetraazacyclotetradeca-1,3-diene), is formed in situ. Cyclic voltammetry and density functional theory (DFT) calculations show that this complex is reduced by two electrons, the first of which is coupled with nitrite ligand loss, to provide the active catalyst. Experimental observations suggest that the key N-O bond cleavage step is facilitated by intramolecular proton transfer from an amine group of the macrocycle to a nitro ligand, as supported by modeling several potential reaction pathways with DFT. These results provide insights into how the combination of a redox active ligand and first-row transition metal can facilitate the multiproton/electron process of nitrite reduction.

The adsorption of gases on the surface of solid solutions and binary compounds of the GaSb-ZnTe system

Kirovskaya,Novgorodtseva,Vasina

, p. 1532 - 1536 (2007)

The adsorption of ammonia, carbon monoxide, and oxygen on solid solution and binary compound films of the GaSb-ZnTe system was studied. The mechanism of adsorption and rules governing adsorption processes depending on adsorption conditions and system comp

Kinetics and mechanism of thermal decomposition of ammonium nitrate and sulfate mixtures

Kazakov,Ivanova,Kurochkina,Plishkin

, p. 1516 - 1523 (2011)

Fundamental kinetic aspects of the decomposition of mixtures and double salts of ammonium nitrate and ammonium sulfate were studied. The effect of water and sulfuric acid additives on the thermal decomposition rate of ammonium nitrate and sulfate mixtures was examined. The constant of proton exchange between nitric acid and the sulfate anion in molten ammonium nitrate was estimated.

Iron Porphyrin-based Electrocatalytic Reduction of Nitrite to Ammonia

Barley, Mark H.,Takeuchi, Kenneth,Murphy, W. Rorer,Meyer, Thomas J.

, p. 507 - 508 (1985)

Electrocatalytic reduction of nitrite to ammonia has been demonstrated using a water-soluble iron porphyrin as catalyst.

Grubb

, p. 658 (1926)

Fixation of Molecular Nitrogen in Aqueous Solution Induced by Nitrogen Arc Plasma

Takasaki, Michiaki,Harada, Kaoru

, p. 437 - 440 (1987)

Argon Arc Plasma containing nitrogen gas (nitrogen arc plasma) was directly introduced into water, and a disproportionation reaction of molecular nitrogen took place in aqueous solution to form ammonia, nitrous acid, and nitric acid.The redox reaction of molecular nitrogen is interesting on the chemical evolutionary point of view as a possible route for the formation of ammonia under nonreducing conditions.

Interaction of nitric oxide with cobalt(II) tetrasulfophthalocyanine

Vilakazi, Sibulelo,Nyokong, Tebello

, p. 229 - 234 (2000)

The interaction of nitric oxide (NO) with cobalt(II) tetrasulfophthalocyanine [Co(II)TSPc]4-) has been studied. Coordination of NO is accompanied by electron transfer from the central metal in [Co(II)TSPc]4-, the resulting complex being represented as [(NO-)Co(III)TSPc]4-. The rate constant for the formation of this species is k(f)-= 142 ± 7 dm3 mol-1 s-1 and an equilibrium constant of 3.0 ± 0.5 x 105 dm3 mol-1 was obtained. When adsorbed to a glassy carbon electrode, [Co (II) TSPc]4- catalyses the oxidation and reduction of NO, with a detection limit of the order of 10-9 mol dm-3. Ammonia and hydroxylamine are some of the reduction products obtained for the reduction of NO on [Co(II)TSPc]4- -modified glassy carbon electrodes. (C) 2000 Elsevier Science Ltd.

Ti3C2Tx (T = F, OH) MXene nanosheets: Conductive 2D catalysts for ambient electrohydrogenation of N2 to NH3

Zhao, Jinxiu,Zhang, Lei,Xie, Xiao-Ying,Li, Xianghong,Ma, Yongjun,Liu, Qian,Fang, Wei-Hai,Shi, Xifeng,Cui, Ganglong,Sun, Xuping

, p. 24031 - 24035 (2018)

The Haber-Bosch process for industrial-scale NH3 production suffers from high energy consumption and serious CO2 emission. Electrochemical N2 reduction is an attractive carbon-neutral alternative for NH3 synthesis but is severely restricted due to N2 activation needing efficient electrocatalysts for the N2 reduction reaction (NRR) under ambient conditions. Here, we report that Ti3C2Tx (T = F, OH) MXene nanosheets act as high-performance 2D NRR electrocatalysts for ambient N2-to-NH3 conversion with excellent selectivity. In 0.1 M HCl, such catalysts achieve a large NH3 yield of 20.4 g h-1 mgcat.-1 and a high faradic efficiency of 9.3% at -0.4 V vs. reversible hydrogen electrode, with high electrochemical and structural stability. Density functional theory calculations reveal that N2 chemisorbed on Ti3C2Tx experiences elongation/weakness of the NN triple bond facilitating its catalytic conversion to NH3 and the distal NRR mechanism is more favorable with the final reaction of ?NH2 to NH3 as the rate-limiting step.

An Iodido-Bridged Dimer of Cubane-Type RuIr3S4 Cluster: Structural Rearrangement to New Octanuclear Core and Catalytic Reduction of Hydrazine

Seino, Hidetake,Hirata, Keiichi,Arai, Yusuke,Jojo, Risa,Okazaki, Masaaki

, p. 1483 - 1489 (2020)

Nitrogen-fixing enzymes contain octanuclear metal–sulfur clusters at the active site, which are constructed on the basis of combined two cubic M4S3C skeletons. In this study, the dimer of cubane-type RuIr3S4 cluster [{(Cp*Ir)3(μ3-S)4Ru}2(μ2-I)3]I (2: Cp* = η5-C5Me5) was synthesized via oxidation of [(Cp*Ir)3(μ3-S)4(CymRu)] (Cym = η6-p-iPrC6H4Me) with I2 followed by ligand exchange. Two cubane cores are bridged by three iodido ligands in 2, while these cubes are fused into a unique Ru2Ir6S8 framework by 2e-reductuion to give [(Cp*Ir)6Ru2(μ3-S)8][I]2. Addition of excess PhNHNH2 to 2 cleaved the dimer structure to form the hydrazine adduct of single cubane [(Cp*Ir)3(μ3-S)4{RuI(NH2NHPh)2}]I. Reduction of N2H4 with Cp2Co and [HNEt3][BF4] was catalyzed by 2 in much higher rate than disproportionation of N2H4. The molecular structures of all new cluster compounds were characterized by X-ray diffraction studies.

Synthesis, characterization and reactivity of thiolate-bridged cobalt-iron and ruthenium-iron complexes

Guo, Chao,Su, Linan,Yang, Dawei,Wang, Baomin,Qu, Jingping

, p. 217 - 220 (2022)

Thiolate-bridged hetero-bimetallic complexes [Cp*M(MeCN)N2S2FeCl][PF6] (2, M = Ru; 3, M = Co, Cp* = η5-C5Me5, N2S2 = N,N'-dimethyl-3,6-diazanonane-1,8-dithiolate) were prepared by self-assembly of dimer [N2S2Fe]2 with mononuclear precursor [Cp*Ru(MeCN)3][PF6] or [Cp*Co(MeCN)3][PF6]2 in the presence of CHCl3 as a chloride donor. Complexes 2 and 3 exhibit obviously different redox behaviors investigated by cyclic voltammetry and spin density distributions supported by DFT calculations. Notably, iron-cobalt complex 3 possesses versatile reactivities that cannot be achieved for complex 2. In the presence of CoCp2, complex 3 can undergo one-electron reduction to generate a stable formally CoIIFeII complex [Cp*CoN2S2FeCl] (4). Besides, the terminal chloride on the iron center in 3 can be removed by dehalogenation agent AgPF6 or exchanged with azide to afford the corresponding complexes [Cp*Co(MeCN)N2S2Fe(MeCN)][PF6]2 (5) and [Cp*Co(MeCN)N2S2Fe(N3)][PF6] (6). In addition, complexes 2, 3 and 4 show distinct catalytic reactivity toward the disproportionation of hydrazine into ammonia. These results may be helpful to understand the vital role of the heterometal in some catalytic transformations promoted by heteromultinuclear complexes.

Graphdiyne Interface Engineering: Highly Active and Selective Ammonia Synthesis

Chen, Xi,Fang, Yan,Gao, Yang,Huang, Bolong,Hui, Lan,Li, Yongjun,Li, Yuliang,Liu, Yuxin,Wang, Zhongqiang,Xing, Chengyu,Xue, Yurui,Yu, Huidi,Zhang, Chao,Zhang, Danyan

, p. 13021 - 13027 (2020)

A freestanding 3D graphdiyne–cobalt nitride (GDY/Co2N) with a highly active and selective interface is fabricated for the electrochemical nitrogen reduction reaction (ECNRR). Density function theory calculations reveal that the interface-bonded GDY contributes an unique p-electronic character to optimally modify the Co-N compound surface bonding, which generates as-observed superior electronic activity for NRR catalysis at the interface region. Experimentally, at atmospheric pressure and room temperature, the electrocatalyst creates a new record of ammonia yield rate (Y (Formula presented.)) and Faradaic efficiency (FE) of 219.72 μg h?1 mgcat.?1 and 58.60 percent, respectively, in acidic conditions, higher than reported electrocatalysts. Such a catalyst is promising to generate new concepts, new knowledge, and new phenomena in electrocatalytic research, driving rapid development in the field of electrocatalysis.

Triple C-H/N-H activation by O2 for molecular engineering: Heterobifunctionalization of the 19-electron redox catalyst Fe1Cp(arene)

Rigaut,Delville,Astruc

, p. 11132 - 11133 (1997)

-

Grubb

, p. 671 (1923)

Photocatalytic reduction of hydrazine to ammonia catalysed by [RuIII(edta)(H2O)]- complex in a Pt/TiO2 semiconductor particulate system

Chatterjee

, p. 1 - 3 (2000)

The illumination of aqueous suspensions of Pt/TiO2 semicondutor photocatalyst with [RuIII(edta)(H2O)]- led to the reduction of hydrazine to ammonia. Coordination of hydrazine to [RuIII(edta)(H2O)]- lowered the energy barrier significantly for the reduction of hydrazine. The rate controlling step of photocatalytic process was probably a surface chemical step (electron transfer) possibly coupled with adsorption of reactants and desorption of ammonia molecule. A working mechanism involving the formation of a [(RuIII(edta)(N2H5)] species (adsorbed onto TiO2 surface) that underwent two-electron transfer reduction followed by cleavage of the N-N bond of coordinated hydrazine was proposed.

Ray, P. Ch.,Jana, S. Ch.

, p. 1565 - 1567 (1913)

Reactive Ionic Liquid Enables the Construction of 3D Rh Particles with Nanowire Subunits for Electrocatalytic Nitrogen Reduction

Chen, Tingting,Hao, Jingcheng,Li, Zhonghao,Liu, Shuai,Ying, Hao

, (2020)

Until now, the synthesis of Rh particles with unusual three-dimensional (3D) nanostructures is still challenging. A 3D nanostructure enables fast ion/molecule transport and possesses plenty of exposed active surface, and therefore it is of great interest to construct 3D Rh particles catalysts for the N2 reduction reaction (NRR). Herein, we proposed a reactive ionic liquid strategy for fabricating unusual 3D Rh particles with nanowires as the subunits. The ionic liquid n-octylammonium formate simultaneously worked as reaction medium, reductant and template for the successful construction of 3D Rh particles. The as-prepared 3D Rh particles demonstrated excellent activity for electrocatalytic N2 fixation in 0.1 M KOH electrolyte under ambient conditions with a high NH3 yield of 35.58 μg h?1 mgcat. ?1 at ?0.2 V versus reversible hydrogen electrode (RHE), surpassing most of the state-of-the-art noble metal catalysts. Our reactive ionic liquid strategy thus holds great promise for the rational construction of high-performance electrocatalysts toward NRR.

REDUCTION OF NITRIC OXIDE BY CARBON MONOXIDE AND WATER IN AN AQUEOUS ALKALINE SOLUTIONS OF HEXARHODIUM HEXADECACARBONYL AND TETRARHODIUM DODECACARBONYL COMPLEXES

Naito, Shuichi,Tamaru, Kenzi

, p. 1833 - 1836 (1982)

The reduction of nitric oxide to ammonia was examined in an aqueous KOH solution of Rh6(CO)16 or Rh4(CO)12 complex.It is confirmed that the water gas shift reaction is incorporated with this reaction, providing hydrogen for ammonia formation.

Ligand-field photolysis of [Mo(CN)8]4- in aqueous hydrazine: Trapped Mo(II) intermediate and catalytic disproportionation of hydrazine by cyano-ligated Mo(III,IV) complexes

Szklarzewicz, Janusz,Matoga, Dariusz,Klys, Agnieszka,Lasocha, Wieslaw

, p. 5464 - 5472 (2008)

The substitutional photolysis of K4[Mo(CN)8] ·2H2O in 98% N2H4·H2O has been investigated in detail. A molybdenum(II) intermediate, K 5[Mo(CN)7]·N2H4, is isolated in the primary stage of the reaction that involves the oxidation of N 2H4 to N2, as evidenced by the analysis of evolving gases. The powder X-ray crystal structure of K5[Mo(CN) 7]·N2H4 indicates the pentagonal bipiramidal geometry of the anion and the presence of N2H4 in proximity to the CN- ligands. The salt is characterized by means of EDS, IR, UV-vis, and EPR spectroscopy as well as cyclic voltammetry measurements. The secondary stages of photolysis, involving the catalytic decomposition of N2H4 into NH3 and N 2, lead to the formation of a molybdenum(IV) complex, [Mo(CN) 4O(NH3)]2-. The monitoring of the amounts of evolving gases combined with UV-vis and EPR spectroscopic measurements at various stages of photolysis indicate that the molybdenum(III,IV) couple is catalytically active. The scheme of the catalytic decomposition of hydrazine is presented and discussed.

Three-way catalytic reactions on Rh-based catalyst: Effect of Rh/ceria interfaces

Wang, Chengxiong,Zheng, Tingting,Lu, Jun,Wu, Xiaodong,Hochstadt, Harold,Zhao, Yunkun

, p. 30 - 39 (2017)

Rh-based catalysts were prepared by various methods and it was found that preparation methods play an important role in metal-support interaction (MSI) control which affects the catalytic performance of catalyst. The results suggest that the catalytic reduction of NO is mainly achieved by C3H6 in exhaust and H2 generated from the water-gas shift reaction as well as the steam reforming of C3H8 and CH4. Concentration of water in reaction stream has a significant influence on the water-gas shift and steam reforming reactions. The removal of C3H6 is accomplished by oxygen-induced oxidation instead of steam reforming reaction. In addition, Rh/ceria interactions promote the formation of active oxygen species and surface oxygen vacancy that respectively favors CO oxidation and NO reduction with a high N2 selectivity. Rh@CeO2 system shows high thermal stability due to Rh/ceria interaction.

A thiolate-bridged FeIVFeIV μ-nitrido complex and its hydrogenation reactivity toward ammonia formation

Chen, Hui,Mei, Tao,Qu, Jingping,Wang, Baomin,Wang, Junhu,Yang, Dawei,Ye, Shengfa,Zhang, Yixin,Zhao, Jinfeng,Zhou, Yuhan

, p. 46 - 52 (2021/12/27)

Iron nitrides are key intermediates in biological nitrogen fixation and the industrial Haber–Bosch process, used to form ammonia from dinitrogen. However, the proposed successive conversion of nitride to ammonia remains elusive. In this regard, the search for well-described multi-iron nitrido model complexes and investigations on controlling their reactivity towards ammonia formation have long been of great challenge and importance. Here we report a well-defined thiolate-bridged FeIVFeIV μ-nitrido complex featuring an uncommon bent Fe–N–Fe moiety. Remarkably, this complex shows excellent reactivity toward hydrogenation with H2 at ambient conditions, forming ammonia in high yield. Combined experimental and computational studies demonstrate that a thiolate-bridged FeIIIFeIII μ-amido complex is a key intermediate, which is generated through an unusual two-electron oxidation of H2. Moreover, ammonia production was also realized by treating this diiron μ-nitride with electrons and water as a proton source. [Figure not available: see fulltext.].

Atomic defects in pothole-rich two-dimensional copper nanoplates triggering enhanced electrocatalytic selective nitrate-to-ammonia transformation

Li, Xiaonian,Liu, Mengying,Ren, Kaili,Ren, Tianlun,Wang, Hongjing,Wang, Liang,Wang, Mingzhen,Wang, Ziqiang,Xu, You

supporting information, p. 16411 - 16417 (2021/08/09)

The development of efficient catalysts for electrocatalytic selective conversion of nitrate pollutants into valuable ammonia is a project of far-reaching importance. This work demonstrated thein situelectroreduction of pre-synthesized CuO nanoplates into defect-rich metallic Cu nanoplates and evaluated their electrocatalytic nitrate-to-ammonia activity. Concentrated atomic defects in the as-converted Cu nanoplates could favor the adsorption, enrichment and confinement of nitrate ions and pivotal reaction intermediates, selectively promoting eight-electron reduction (NH3formation). Consequently, the resultant defect-rich Cu nanoplates exhibit a significant ammonia production rate of 781.25 μg h?1mg?1, together with excellent nitrate conversion (93.26%), high ammonia selectivity (81.99%) and good electrocatalytic stability, superior to the defect-free Cu nanoplate counterpart. Isotope labelling experiments demonstrated that the source of ammonia was from nitrate. Both1H NMR and colorimetric methods were used to quantify the ammonia yield.

Visible light enables catalytic formation of weak chemical bonds with molecular hydrogen

Park, Yoonsu,Kim, Sangmin,Tian, Lei,Zhong, Hongyu,Scholes, Gregory D.,Chirik, Paul J.

, p. 969 - 976 (2021/07/25)

The synthesis of weak chemical bonds at or near thermodynamic potential is a fundamental challenge in chemistry, with applications ranging from catalysis to biology to energy science. Proton-coupled electron transfer using molecular hydrogen is an attractive strategy for synthesizing weak element–hydrogen bonds, but the intrinsic thermodynamics presents a challenge for reactivity. Here we describe the direct photocatalytic synthesis of extremely weak element–hydrogen bonds of metal amido and metal imido complexes, as well as organic compounds with bond dissociation free energies as low as 31 kcal mol?1. Key to this approach is the bifunctional behaviour of the chromophoric iridium hydride photocatalyst. Activation of molecular hydrogen occurs in the ground state and the resulting iridium hydride harvests visible light to enable spontaneous formation of weak chemical bonds near thermodynamic potential with no by-products. Photophysical and mechanistic studies corroborate radical-based reaction pathways and highlight the uniqueness of this photodriven approach in promoting new catalytic chemistry. [Figure not available: see fulltext.].

Ammonia Formation Catalyzed by a Dinitrogen-Bridged Dirhenium Complex Bearing PNP-Pincer Ligands under Mild Reaction Conditions**

Egi, Akihito,Kuriyama, Shogo,Meng, Fanqiang,Nishibayashi, Yoshiaki,Tanaka, Hiromasa,Yoshizawa, Kazunari

supporting information, p. 13906 - 13912 (2021/05/13)

A series of rhenium complexes bearing a pyridine-based PNP-type pincer ligand are synthesized from rhenium phosphine complexes as precursors. A dinitrogen-bridged dirhenium complex bearing the PNP-type pincer ligands catalytically converts dinitrogen into ammonia during the reaction with KC8 as a reductant and [HPCy3]BArF4 (Cy=cyclohexyl, ArF=3,5-(CF3)2C6H3) as a proton source at ?78 °C to afford 8.4 equiv of ammonia based on the rhenium atom of the catalyst. The rhenium-dinitrogen complex also catalyzes silylation of dinitrogen in the reaction with KC8 as a reductant and Me3SiCl as a silylating reagent under ambient reaction conditions to afford 11.7 equiv of tris(trimethylsilyl)amine based on the rhenium atom of the catalyst. These results demonstrate the first successful example of catalytic nitrogen fixation under mild reaction conditions using rhenium-dinitrogen complexes as catalysts.

Process route upstream and downstream products

Process route

hydrogenchloride
7647-01-0,15364-23-5

hydrogenchloride

3,4-dibromo-1,2,5-oxadiazole 2-oxide
70134-71-3

3,4-dibromo-1,2,5-oxadiazole 2-oxide

ammonia
7664-41-7

ammonia

hydrogen bromide
10035-10-6,12258-64-9

hydrogen bromide

hydroxylamine
7803-49-8

hydroxylamine

Conditions
Conditions Yield
at 100 ℃; im Rohr;
hydrogenchloride
7647-01-0,15364-23-5

hydrogenchloride

2-methyl-5-phenyl-2H-tetrazole
20743-49-1

2-methyl-5-phenyl-2H-tetrazole

5-Phenyl-1H-tetrazole
18039-42-4,3999-10-8

5-Phenyl-1H-tetrazole

methylene chloride
74-87-3

methylene chloride

ammonia
7664-41-7

ammonia

methylamine
74-89-5

methylamine

Conditions
Conditions Yield
at 150 ℃; und andere Zersetzungsprodukte;
(4,4-dibromo-5-oxo-4,5-dihydro-[1,2,3]triazol-1-yl)-acetic acid amide
860569-66-0

(4,4-dibromo-5-oxo-4,5-dihydro-[1,2,3]triazol-1-yl)-acetic acid amide

water
7732-18-5

water

ammonia
7664-41-7

ammonia

hydrogen bromide
10035-10-6,12258-64-9

hydrogen bromide

Conditions
Conditions Yield
(4,4-dibromo-5-oxo-4,5-dihydro-[1,2,3]triazol-1-yl)-acetic acid amide
860569-66-0

(4,4-dibromo-5-oxo-4,5-dihydro-[1,2,3]triazol-1-yl)-acetic acid amide

ammonia
7664-41-7

ammonia

hydrogen bromide
10035-10-6,12258-64-9

hydrogen bromide

Conditions
Conditions Yield
4-nitro-aniline
100-01-6,104810-17-5

4-nitro-aniline

furan-2,3,5(4H)-trione pyridine (1:1)

furan-2,3,5(4H)-trione pyridine (1:1)

ammonia
7664-41-7

ammonia

Conditions
Conditions Yield
ethanol
64-17-5

ethanol

1-(1-naphthyl)-biguanide
13261-53-5

1-(1-naphthyl)-biguanide

ammonia
7664-41-7

ammonia

1-amino-naphthalene
134-32-7

1-amino-naphthalene

Conditions
Conditions Yield
1-(1-naphthyl)hydrazine
2243-55-2

1-(1-naphthyl)hydrazine

ammonia
7664-41-7

ammonia

1-amino-naphthalene
134-32-7

1-amino-naphthalene

Conditions
Conditions Yield
beim Erhitzen ueber den Schmelzpunkt;
water
7732-18-5

water

2-bromo-maleic acid-1-ureide
62891-84-3

2-bromo-maleic acid-1-ureide

carbon dioxide
124-38-9,18923-20-1

carbon dioxide

ammonia
7664-41-7

ammonia

hydrogen bromide
10035-10-6,12258-64-9

hydrogen bromide

Conditions
Conditions Yield
at 60 - 70 ℃;
2-hydroxybenzaldehyde phenylhydrazone
614-65-3

2-hydroxybenzaldehyde phenylhydrazone

salicylonitrile
611-20-1

salicylonitrile

ammonia
7664-41-7

ammonia

aniline
62-53-3

aniline

Conditions
Conditions Yield
at 294 ℃; durch Destillation;
terephthalohydrazide
136-64-1

terephthalohydrazide

terephthalic acid
100-21-0

terephthalic acid

ammonia
7664-41-7

ammonia

Conditions
Conditions Yield
beim Erhitzen ueber den Schmelzpunkt;

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