Multimetallic Cooperative Activation of N<sub>2</sub>

Gambarotta, Sandro; Scott, Jennifer

doi:10.1002/anie.200301669

Cited by 283 publications

(151 citation statements)

References 82 publications

(63 reference statements)

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“…[61] More recently, nitrogen activation has also been achieved by complexes of nonclassical divalent lanthanides. [62] Furthermore, various organic and inorganic molecules react with 68 and 66. [63] In another striking breakthrough, Evans et al found that the extremely sterically crowded complex 67 (Figure 3), containing three Cp* rings around the Sm metal, can be structurally characterized and that it acts as a powerful singleelectron reductant despite the three-valent oxidation state of Sm.…”

Section: Samarium(ii) Cyclopentadienyl Complexesmentioning

confidence: 99%

Beyond Samarium Diiodide: Vistas in Reductive Chemistry Mediated by Lanthanides(II)

2012

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Reactions proceeding through open-shell, single-electron pathways offer attractive alternative outcomes to those proceeding through closed-shell, two-electron mechanisms. In this context, samarium diiodide (SmI(2)) has emerged as one of the most important and convenient-to-use electron-transfer reagents available in the laboratory. Recently, significant progress has been made in the reductive chemistry of other divalent lanthanides which for many years had been considered too reactive to be of value to synthetic chemists. Herein, we illustrate how new samarium(II) complexes and nonclassical lanthanide(II) reagents are changing the landscape of modern reductive chemistry.

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Section: Samarium(ii) Cyclopentadienyl Complexesmentioning

confidence: 99%

Beyond Samarium Diiodide: Vistas in Reductive Chemistry Mediated by Lanthanides(II)

2012

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“…). 24) In order to confirm the dynamic behavior of the reduction and nitriding of hematite with ammonia, commercial hematite and metallic iron reagents were subjected to in-situ XRD measurements. Figure 4 shows the in-situ XRD profiles obtained during heating from 298 to 973 K of the two reagents in a stream of 5% NH3 diluted with helium.…”

Section: Mechanisms Of Hematite Reduction and Nitridingmentioning

confidence: 99%

Reduction and Nitriding Behavior of Hematite with Ammonia

et al. 2015

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This paper describes the reduction and nitriding behavior of hematite with ammonia in the context of ironmaking. The effects of temperature and ammonia concentration on the products were investigated. In the temperature range from 793 to 863 K, hematite was directly reduced to magnetite by ammonia (1/2Fe2O3 + 1/9NH3 → 1/3Fe3O4 + 1/6H2O + 1/18N2). The ammonia started to decompose at 873 K, triggered by the generation of α-Fe. Magnetite was reduced mainly to iron by hydrogen generated from the decomposition of ammonia (1/3Fe3O4 + 4/3H2 → Fe + 4/3H2O). According to in-situ X-ray diffraction (XRD) measurements, α-Fe was immediately nitrided to an ε-Fe 3-x N (0 ≤ x ≤ 1) phase, and the N/Fe atomic ratio decreased gradually with increasing temperatures. The rate of hematite reduction increased with the ammonia concentration for 5% to 20% NH3, but plateaus for NH3 concentrations greater than 20%. This was attributed to the mechanism of ammonia decomposition; the amount of hydrogen generated also plateaus at ammonia concentrations above 20%. The reduction rate was therefore limited by the rate at which hydrogen was generated during ammonia decomposition. The N content of the product was affected not only by the temperature but also by the nitriding potential (KN = P NH 3 /P H 2 3/2 ). The nitriding potential increased with increasing ammonia concentrations and decreasing temperatures. The addition of nitrogen gas to the reactive gas inhibited ammonia decomposition and increased the nitrogen potential and N content of the product.

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“…[1,2] 3 , with N 2 bridging the metal centers end-on, followed by N-N bond cleavage to form the nitride product NMo[N(tBu)Ar] 3 . [3][4][5] The reaction proceeds under mild conditions (1 atm of pressure and between -33 and 25°C) compared with the extreme conditions of 200 atm and 500°C required in the industrial Haber-Bosch process for nitrogen fixation.…”

Section: Introductionmentioning

confidence: 99%

Cleavage of CO by Mo[N(R)Ar]₃ Complexes

et al. 2007

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The reaction of MoL3 [L = NH2 and N(tBu)Ar] with CO was explored using DFT in order to rationalize why CO cleavage is not observed experimentally for this system in contrast to the corresponding N2 reaction which results in spontaneous cleavage of the N–N bond. The binding of CO to MoL3 was found to be both kinetically and thermodynamically favored over the binding of N2, with the formation of the encounter complex, L3Mo–CO, calculated to be without barrier and exothermic. While the overall reaction to form the C–MoL3 and O–MoL3 products was calculated to be energetically favorable, both the encounter complex and intermediate dimer, L3Mo–CO–MoL3, were found to be lower in energy than the products, with the final C–O cleavage step calculated to be endothermic by 169 kJ mol–1 and 163 kJ mol–1 for L = NH2 and N(tBu)Ar, respectively. The unfavorable CO cleavage step can be attributed to the fact that Mo does not possess the optimum d‐electron configuration to sufficiently stabilise the carbide and oxide products relative to the CO‐bridged intermediate dimer.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

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Multimetallic Cooperative Activation of N₂

Cited by 283 publications

References 82 publications

Beyond Samarium Diiodide: Vistas in Reductive Chemistry Mediated by Lanthanides(II)

Beyond Samarium Diiodide: Vistas in Reductive Chemistry Mediated by Lanthanides(II)

Reduction and Nitriding Behavior of Hematite with Ammonia

Cleavage of CO by Mo[N(R)Ar]₃ Complexes

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Multimetallic Cooperative Activation of N2

Cited by 283 publications

References 82 publications

Beyond Samarium Diiodide: Vistas in Reductive Chemistry Mediated by Lanthanides(II)

Beyond Samarium Diiodide: Vistas in Reductive Chemistry Mediated by Lanthanides(II)

Reduction and Nitriding Behavior of Hematite with Ammonia

Cleavage of CO by Mo[N(R)Ar]3 Complexes

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Multimetallic Cooperative Activation of N₂

Cleavage of CO by Mo[N(R)Ar]₃ Complexes