Cleavage of Dinitrogen from Forming Gas by a Titanium Molecular System under Ambient Conditions

González-Moreiras, Mariano; Mena, Miguel; Pérez‐Redondo, Adrián; Yélamos, Carlos

doi:10.1002/chem.201700152

Cited by 18 publications

(18 citation statements)

References 69 publications

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“…Some early-transition-metal hydrides are reported to split and hydrogenate N 2 in the solid state in combination with H 2 . − For well-defined molecular metal hydride systems, Fryzuk and Kawaguchi reported some dinuclear group 5 transition-metal tantalum and niobium , polyhydride complexes which can reduce and split N 2 . We reported several di-, tri-, and tetranuclear group 4 transition metal titanium polyhydride complexes that enable N 2 cleavage and partial hydrogenation without an extra electron or proton source. − Yélamos and co-workers reported the formation of a mixed nitride/methylidene/methylidyne tetranuclear titanium complex from the reaction of a titanium trimethyl complex with a mixture of H 2 and N 2 . To date, well-defined transition-metal hydride complexes that enable N 2 cleavage and hydrogenation have been limited only to group 4 and 5 transition metals.…”

Section: Introductionmentioning

confidence: 99%

Dinitrogen Activation and Hydrogenation by C₅Me₄SiMe₃-Ligated Di- and Trinuclear Chromium Hydride Complexes

et al. 2020

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Activation of dinitrogen (N2) by well-defined metal hydrides is of much interest and importance, but studies in this area have remained limited to date. We report here N2 activation and hydrogenation by C5Me4SiMe3-ligated di- and trinuclear chromium polyhydride complexes. Hydrogenolysis of [Cp′Cr(μ-Me)2CrCp′] (Cp′ = C5Me4SiMe3) (1) with H2 in a dilute hexane solution under N2-free conditions affords the dichromium dihydride complex [Cp′Cr(μ-H)2CrCp′] (2), while hydrogenolysis of 1 in a concentrated solution or without solvent provides the trinuclear chromium tetrahydride complex [(Cp′Cr)3(μ3-H)(μ-H)3] (3). When the reaction is carried out in the presence of N2 in a dilute hexane solution, the tetranuclear diimide/dihydride complex [(Cp′Cr)4(μ3-NH)2(μ3-H)2] (4) is formed via N–N bond cleavage and N–H bond formation. The reaction of 2 with N2 at room temperature gives the tetranuclear imide/nitride/dihydride complex [(Cp′Cr)3(C5Me3(CH2)SiMe3)Cr(μ3-NH)(μ3-N)(μ-H)2] (5) via N2 cleavage and hydrogenation and C–H bond activation of a Cp methyl group. At –30 °C, the reaction of 2 with N2 affords the dinitride intermediate [(Cp′Cr)4(μ3-N)2(μ3-H)2] (6), which is quantitatively transformed to 5 at room temperature. Complex 5 reversibly converts to the stereoisomer 5′. The hydrogenation of a mixture of 5 and 5′ with H2 affords 4. The reaction of 3 with N2 proceeds at 100 °C to afford [(Cp′Cr)3(μ3-NH)2] (7). This transformation has also been investigated by DFT calculations. Both experimental and computational studies suggest that N2 incorporation into the chromium hydride cluster is involved in the rate-determining step. This work represents the first example of N2 cleavage and hydrogenation by well-defined chromium hydride complexes.

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Section: Introductionmentioning

confidence: 99%

Dinitrogen Activation and Hydrogenation by C₅Me₄SiMe₃-Ligated Di- and Trinuclear Chromium Hydride Complexes

et al. 2020

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“…This transformation demonstrated the unique reactivity of a multimetallic polyhydride complex. − However, studies on N 2 activation by well-defined multimetallic hydride complexes are still scarce. The reaction of a tetranuclear or higher nuclear metal hydride complex with N 2 has remained almost unexamined to date. ,, …”

Section: Introductionmentioning

confidence: 99%

Experimental and Computational Studies of Dinitrogen Activation and Hydrogenation at a Tetranuclear Titanium Imide/Hydride Framework

Shima

Luo

et al. 2019

J. Am. Chem. Soc.

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The activation of N2 by a tetranuclear titanium(III) diimide/tetrahydride complex, [(Cp′Ti)4(μ3-NH)2(μ-H)4] (1) (Cp′ = C5Me4SiMe3), which was obtained by the reaction of the Cp′-ligated titanium trialkyl complex Cp′Ti(CH2SiMe3)3 with H2 and N2, was investigated in detail by experimental and density functional theory studies. The reaction of 1 in the solid state with N2 (1 atm) at 180 °C gave the dinitride/diimide complex [(Cp′Ti)4(μ3-N)2(μ3-NH)2] (2) through the incorporation, cleavage, and partial hydrogenation of one molecule of N2 and release of two molecules of H2. At 130 °C, the formation of 2 was not observed, but instead, dehydrogenation of 1 took place through cleavage of the N–H bond in an imide ligand, followed by deprotonation of the other imide ligand with a hydride ligand, affording the dinitride/tetrahydride complex [(Cp′Ti)4(μ3-N)2(μ-H)4] (3). Upon heating under N2 (1 atm) at 180 °C, 3 was quantitatively converted to the dinitride/diimide complex 2. This transformation was initiated by migration of a hydride ligand to a nitride ligand to give one imide unit, followed by N2 coordination to a Ti atom and H2 release through the reductive elimination of two hydride ligands. The other imide ligand in 2 was formed by hydride migration to one of the two nitride ligands generated through the cleavage of the newly incorporated N2 unit. The hydrogenation of 2 with H2 (100 atm) at 180 °C afforded the tetraimide complex [(Cp′Ti)4(μ3-NH)4] (4). This reaction was initiated by σ-bond metathesis between H2 and a titanium–nitride bond, followed by migration of the resulting hydride ligand to the remaining nitride ligand. In all of these transformations, the interplay among the hydride, imide, and nitride ligands, including the reversible dehydrogenation/hydrogenation of imide and nitride species, at the multimetallic titanium framework has a critically important role.

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“…[8] Where Ti is concerned, cleavage of N 2 by molecular polyhydrides and low valent species and/or stoichiometric protonolysis has been reported. [12] Recently,aheterogeneous Ti hydride was found to catalytically convert N 2 and H 2 into NH 3 ,w hilst TiO 2 is known to photolytically convert N 2 and H 2 Oi nto NH 3 and O 2 . [13] These reports hint that Ti could hold significant promise in this arena.…”

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Catalytic Dinitrogen Reduction to Ammonia at a Triamidoamine–Titanium Complex

et al. 2018

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Catalytic reduction of N2 to NH3 by a Ti complex has been achieved, thus now adding an early d‐block metal to the small group of mid‐ and late‐d‐block metals (Mo, Fe, Ru, Os, Co) that catalytically produce NH3 by N2 reduction and protonolysis under homogeneous, abiological conditions. Reduction of [TiIV(TrenTMS)X] (X=Cl, 1A; I, 1B; TrenTMS=N(CH2CH2NSiMe3)3) with KC8 affords [TiIII(TrenTMS)] (2). Addition of N2 affords [{(TrenTMS)TiIII}2(μ‐η1:η1‐N2)] (3); further reduction with KC8 gives [{(TrenTMS)TiIV}2(μ‐η1:η1:η2:η2‐N2K2)] (4). Addition of benzo‐15‐crown‐5 ether (B15C5) to 4 affords [{(TrenTMS)TiIV}2(μ‐η1:η1‐N2)][K(B15C5)2]2 (5). Complexes 3–5 treated under N2 with KC8 and [R3PH][I], (the weakest H+ source yet used in N2 reduction) produce up to 18 equiv of NH3 with only trace N2H4. When only acid is present, N2H4 is the dominant product, suggesting successive protonation produces [{(TrenTMS)TiIV}2(μ‐η1:η1‐N2H4)][I]2, and that extruded N2H4 reacts further with [R3PH][I]/KC8 to form NH3.

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Cleavage of Dinitrogen from Forming Gas by a Titanium Molecular System under Ambient Conditions

Cited by 18 publications

References 69 publications

Dinitrogen Activation and Hydrogenation by C₅Me₄SiMe₃-Ligated Di- and Trinuclear Chromium Hydride Complexes

Dinitrogen Activation and Hydrogenation by C₅Me₄SiMe₃-Ligated Di- and Trinuclear Chromium Hydride Complexes

Experimental and Computational Studies of Dinitrogen Activation and Hydrogenation at a Tetranuclear Titanium Imide/Hydride Framework

Catalytic Dinitrogen Reduction to Ammonia at a Triamidoamine–Titanium Complex

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Cleavage of Dinitrogen from Forming Gas by a Titanium Molecular System under Ambient Conditions

Cited by 18 publications

References 69 publications

Dinitrogen Activation and Hydrogenation by C5Me4SiMe3-Ligated Di- and Trinuclear Chromium Hydride Complexes

Dinitrogen Activation and Hydrogenation by C5Me4SiMe3-Ligated Di- and Trinuclear Chromium Hydride Complexes

Experimental and Computational Studies of Dinitrogen Activation and Hydrogenation at a Tetranuclear Titanium Imide/Hydride Framework

Catalytic Dinitrogen Reduction to Ammonia at a Triamidoamine–Titanium Complex

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Dinitrogen Activation and Hydrogenation by C₅Me₄SiMe₃-Ligated Di- and Trinuclear Chromium Hydride Complexes

Dinitrogen Activation and Hydrogenation by C₅Me₄SiMe₃-Ligated Di- and Trinuclear Chromium Hydride Complexes