Ammonia Synthesis through Hydrolysis of a Trianionic Pincer Ligand‐Supported Molybdenum–Nitride Complex

Chakraborty, Jayasree; Mandal, Ushnish; Ghiviriga, Ion; Abboud, Khalil A.; Veige, Adam S.

doi:10.1002/chem.201903740

Cited by 6 publications

(3 citation statements)

References 59 publications

(132 reference statements)

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“…Although this was unexpected in the first place, it can be rationalized by the fact that somewhere during the catalytic process water must be eliminated to reform the metal–carbene and metal–phenolate bonds. At 130 °C reaction temperature, water is very likely to hydrolyze any imido complex to reform the dioxo complex 1 . The potential of 6 to split azobenzene is furthermore undermined by the fact that complex 1 reduces azobenzene to aniline catalytically using 4 equiv of pinacol as a reducing agent and a catalyst loading of 1 mol % within 4 h at 130 °C (Figure S34).…”

Section: Resultsmentioning

confidence: 99%

“…At 130 °C reaction temperature, water is very likely to hydrolyze any imido complex to reform the dioxo complex 1. 102 The potential of 6 to split azobenzene is furthermore undermined by the fact that complex 1 reduces azobenzene to aniline catalytically using 4 equiv of pinacol as a reducing agent and a catalyst loading of 1 mol % within 4 h at 130 °C (Figure S34). Nevertheless, on re-examining the time conversion data (Figure S33), no azobenzene could be detected in the reaction mixtures.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Catalytic Deoxygenation of Nitroarenes Mediated by High-Valent Molybdenum(VI)–NHC Complexes

et al. 2021

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The high-valent molybdenum(VI) N-heterocyclic carbene complexes, (NHC)MoO 2 (1) and (NHC)MoO(N t Bu) (2) (NHC = 1,3bis(3,5-di-tert-butyl-2-phenolato)-benzimidazol-2-ylidene), are investigated toward their catalytic potential in the deoxygenation of nitroarenes. Using pinacol as the sacrificial and green reductant, both complexes are shown to be very active (pre)catalysts for this transformation allowing a reduction of the catalyst loading down to 0.25 mol %. Mechanistic investigations show μ-oxo bridged molybdenum(V) complexes [(NHC)MoO] 2 O (4) and [(NHC)Mo-(N t Bu)] 2 O (5) as well as zwitterionic pinacolate benzimidazolium complex 6, with a doubly protonated NHC ligand, to be potentially active species in the catalytic cycle. Both 4 and 5 can be prepared independently by the deoxygenation of 1 and 2 using triethyl phosphine (PEt 3 ) or triphenyl phosphine (PPh 3 ) and were shown to exhibit an unusual multireferenced ground state with a very small singlet−triplet gap at room temperature. Computational studies show that the spin state plays an unneglectable role in the catalytic process, efficiently lowering the reaction barrier of the deoxygenation step. Mechanistic details, putting special emphasis on the fate of the catalyst will be presented and potential routes how nitroarene reduction is facilitated are evaluated.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Catalytic Deoxygenation of Nitroarenes Mediated by High-Valent Molybdenum(VI)–NHC Complexes

et al. 2021

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“…However, with M1–N40 distances of 1.995(4) and 1.984(14) Å these are slightly shorter compared to other molybdenum/tungsten–secondary amide interactions reported in the literature (2.00–2.12 Å). 112 − 122 Further studies on the influence of this rearrangement on the reactivity of the oxo ligand (e.g. towards small phosphines) 44 are currently ongoing.…”

Section: Resultsmentioning

confidence: 99%

Expanding the Utility of β-Diketiminate Ligands in Heavy Group VI Chemistry of Molybdenum and Tungsten

et al. 2023

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We report the synthesis of 17 molybdenum and tungsten complexes supported by the ubiquitous BDI ligand framework (BDI = β-diketiminate). The focal entry point is the synthesis of four molybdenum and tungsten(V) BDI complexes of the general formula [MO(BDIR)Cl2] [M = Mo, R = Dipp (1); M = W, R = Dipp (2); M = Mo, R = Mes (3); M = W, R = Mes (4)] synthesized by the reaction between MoOCl3(THF)2 or WOCl3(THF)2 and LiBDIR. Reactivity studies show that the BDIDipp complexes are excellent precursors toward adduct formation, reacting smoothly with dimethylaminopyridine (DMAP) and triethylphosphine oxide (OPEt3). No reaction with small phosphines has been observed, strongly contrasting the chemistry of previously reported rhenium(V) complexes. Additionally, the complexes 1 and 2 are good precursors for salt metathesis reactions. While 1 can be chemically reduced to the first stable example of a Mo(IV) BDI complex 15, reduction of 2 resulted in degradation of the BDI ligand via a nitrene transfer reaction, leading to MAD (4-((2,6-diisopropylphenyl)imino)pent-2-enide) supported tungsten(V) and tungsten(VI) complexes 16 and 17. All reported complexes have been thoroughly studied by VT-NMR and (heteronuclear) NMR spectroscopy, as well as UV–vis and EPR spectroscopy, IR spectroscopy, and X-ray diffraction analysis.

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A hemilabile diphosphine pyridine pincer ligand: σ- and π-binding in molybdenum coordination complexes

et al. 2020

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Ammonia Synthesis through Hydrolysis of a Trianionic Pincer Ligand‐Supported Molybdenum–Nitride Complex

Cited by 6 publications

References 59 publications

Catalytic Deoxygenation of Nitroarenes Mediated by High-Valent Molybdenum(VI)–NHC Complexes

Catalytic Deoxygenation of Nitroarenes Mediated by High-Valent Molybdenum(VI)–NHC Complexes

Expanding the Utility of β-Diketiminate Ligands in Heavy Group VI Chemistry of Molybdenum and Tungsten

A hemilabile diphosphine pyridine pincer ligand: σ- and π-binding in molybdenum coordination complexes

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