Dinitrogen activation by group 4 and group 5 metal complexes supported by phosphine-amido containing ligand manifolds

Burford, Richard J.; Yeo, Alyssa; Fryzuk, Michael D.

doi:10.1016/j.ccr.2016.06.015

Cited by 108 publications

(58 citation statements)

References 82 publications

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“…While some progress has been made on the daunting road to artificial nitrogen activation, the number of well-defined complexes that bind N 2 and ultimately, lead to a complete cleavage of the N≡N triple bond is rather limited so far. For instance, complexes with single (14-32) and multiple (15,(33)(34)(35)(36)(37)(38)(39) transition metal centers, small metal clusters (40)(41)(42)(43)(44)(45)(46)(47)(48), and also, main group compounds (49-52) have been found to be able to split dinitrogen. The activation of N-N bonds by oriented external electric fields (53,54) followed by insertion of, for example, a nitrogen atom in the C-C bonds of alkanes has been reported as well (55,56).…”

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confidence: 99%

“…There are indications that the cooperative activation of N 2 by several transition metal atoms holds promise as well (28, 34-39, 45, 61-64). Furthermore, the reactivity of ditantalum complexes of the type ([NPN]Ta(μ-H)) 2 N 2 ([NPN] = PhP(CH 2 SiMe 2 NPh) 2 ) with dinitrogen (65) has also been extensively investigated in the past (28,34,(61)(62)(63)(64)(65)(66)(67)(68)(69)(70)(71).…”

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confidence: 99%

“…:η 2 -N 2 )(34,63,(65)(66)(67) to form intermediate 1 (−93 kJ mol −1 , C s symmetry) in a barrier-free process. The end-on bonded nitrogen atom (N a ) in 1 has an N a −Ta a bond length of only 1.82 Å, while Ta b binds side on to N a (2.08 Å) and end on to N b (1.90 Å).…”

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confidence: 99%

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Ta₂⁺-mediated ammonia synthesis from N₂and H₂at ambient temperature

Geng

Weiske

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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In a full catalytic cycle, bare Ta2+ in the highly diluted gas phase is able to mediate the formation of ammonia in a Haber–Bosch-like process starting from N2 and H2 at ambient temperature. This finding is the result of extensive quantum chemical calculations supported by experiments using Fourier transform ion cyclotron resonance MS. The planar Ta2N2+, consisting of a four-membered ring of alternating Ta and N atoms, proved to be a key intermediate. It is formed in a highly exothermic process either by the reaction of Ta2+ with N2 from the educt side or with two molecules of NH3 from the product side. In the thermal reaction of Ta2+ with N2, the N≡N triple bond of dinitrogen is entirely broken. A detailed analysis of the frontier orbitals involved in the rate-determining step shows that this unexpected reaction is accomplished by the interplay of vacant and doubly occupied d-orbitals, which serve as both electron acceptors and electron donors during the cleavage of the triple bond of N≡N by the ditantalum center. The ability of Ta2+ to serve as a multipurpose tool is further shown by splitting the single bond of H2 in a less exothermic reaction as well. The insight into the microscopic mechanisms obtained may provide guidance for the rational design of polymetallic catalysts to bring about ammonia formation by the activation of molecular nitrogen and hydrogen at ambient conditions.

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confidence: 99%

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confidence: 99%

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Ta₂⁺-mediated ammonia synthesis from N₂and H₂at ambient temperature

Geng

Weiske

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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“…[42][43][44][45] Many more complexes capable of activating and transforming dinitrogen have been synthesised and characterised, and a number of thorough reviews summarising the current state of the art are available. 24,[46][47][48][49][50][51][52][53][54]…”

Section: Nitrogen Binding In Metal Complexesmentioning

confidence: 99%

Dinitrogen photoactivation: status quo and future perspectives

Krewald

2018

Dalton Trans.

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While the thermal activation of the dinitrogen molecule has been demonstrated in numerous examples with a variety of transition metals and ligand frameworks, the use of light to induce a weakening or splitting of the strong N-N bond is less well explored. Six complexes that bind N in a linear μ-η:η-end-on fashion between two transition metals are known to cleave dinitrogen after absorbing a photon and relaxing from an electronically excited state. This Perspective article reviews the molecular complexes known to be capable of dinitrogen photocleavage, and discusses mechanistic insights into the photoactivation process gained from experimental and computational studies. In an extension of previous hypotheses for pathways to dinitrogen photoactivation that would facilitate easy protonation of the μ-N atoms, a scheme is presented that may help to identify other complexes that could be capable of dinitrogen photoactivation.

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“…Along with the development of the general pincer concept, amidophosphine hybrid ligands, combining hard nitrogen donors and soft phosphines within a tailor‐made ligand framework, have emerged in coordination chemistry. Out of the numerous known P x N y amidophosphines, monoanionic PNP ligands stand out as being well‐suited not only for the complexation of transitions metals, but also for coordinating f‐block and main group elements …”

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confidence: 99%

Phosphines and N‐Heterocycles Joining Forces: an Emerging Structural Motif in PNP‐Pincer Chemistry

2020

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Aminodiphosphines and their monoanionic amido derivatives are among the most widely used tridentate ligands. A good share of these ligands, in particular the ones that are based on a rigid N‐heterocyclic core, is predisposed to coordinate in a meridional fashion. Negatively charged derivatives of these meridionally coordinating N‐heterocyclic ligands satisfy all the criteria for PNP pincer scaffolds. Herein, these ligands and their coordination chemistry is reviewed from the perspective of coordination chemistry. For our discussion, ligands containing a protonated N‐heterocycle (e.g. pyrrole‐ or carbazole‐based PNP scaffolds) are to be distinguished from their counterparts that do not contain such an NH‐functionality (e.g. pyridine‐ or triazine‐based PNP scaffolds). Different synthetic methodologies for the preparation of PNP pincer complexes are presented and shown to often depend on the presence or absence of the aforementioned NH‐proton. The different reactivity patterns of the resulting complexes are sub‐divided into two categories, namely into metal‐centered reactions and reactions that result in a chemical transformation at the metal and the ligand. The latter represent ligand‐cooperative transformations, which often play a key role in catalysis, and are showcased by discussing selected applications in catalysis. It will become evident in this review that this relatively young research field is still emerging and far from reaching maturity. Finally, a brief overview on ligand/metal combinations that have not been explored to date is provided, to stimulate future research on PNP pincers featuring a central N‐heterocycle.

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Dinitrogen activation by group 4 and group 5 metal complexes supported by phosphine-amido containing ligand manifolds

Cited by 108 publications

References 82 publications

Ta₂⁺-mediated ammonia synthesis from N₂and H₂at ambient temperature

Ta₂⁺-mediated ammonia synthesis from N₂and H₂at ambient temperature

Dinitrogen photoactivation: status quo and future perspectives

Phosphines and N‐Heterocycles Joining Forces: an Emerging Structural Motif in PNP‐Pincer Chemistry

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Dinitrogen activation by group 4 and group 5 metal complexes supported by phosphine-amido containing ligand manifolds

Cited by 108 publications

References 82 publications

Ta2+-mediated ammonia synthesis from N2and H2at ambient temperature

Ta2+-mediated ammonia synthesis from N2and H2at ambient temperature

Dinitrogen photoactivation: status quo and future perspectives

Phosphines and N‐Heterocycles Joining Forces: an Emerging Structural Motif in PNP‐Pincer Chemistry

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Product

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Ta₂⁺-mediated ammonia synthesis from N₂and H₂at ambient temperature

Ta₂⁺-mediated ammonia synthesis from N₂and H₂at ambient temperature