Snapshots of Early-Stage Quantitative N<sub>2</sub> Electrophilic Functionalization

Wang, Gao‐Xiang; Wang, Xueli; Jiang, Yang; Chen, Wang; Shan, Chunxiao; Zhang, Peng; Wei, Junnian; Ye, Shengfa; Xi, Zhenfeng

doi:10.1021/jacs.3c01497

Cited by 11 publications

(14 citation statements)

References 60 publications

(69 reference statements)

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“…This prompted us to use low-temperature fast UV–vis spectroscopy to systematically investigate the electrophilic functionalization reactions of Cr(0)–N 2 complexes (Scheme ). The existence of isosbestic points on the UV–visible spectra could clearly show that the stepwise protonation, alkylation, and silylation reactions with HOTf, MeOTf, and Me 3 SiOTf in each step were quantitative conversions at low temperatures . As shown in Figure , upon treatment with one equivalent MeOTf with 20b in a 2-MeTHF solution at 153 K, an isosbestic point at 620 nm was observed, indicative of the quantitative formation of Cr(II)–NN–Me ( 21-Me ).…”

Section: Chromium Dinitrogen Complexes Bearing Cyclopentadienyl and B...mentioning

confidence: 92%

“…In order to achieve more efficient functionalization reactions, we replaced the monophosphine and monocarbene ligands with a simple bisphosphine ligand and synthesized the corresponding dinuclear Cr(I)–N 2 complex 19 and mononuclear Cr(0)–N 2 complex 20 (Scheme ). The magnetometric study of precursor Cr(II) chloride 18 revealed its S = 1 ground state. Compared with the monophosphine and monocarbene analogues, the reduction extent of N 2 units is stronger in both 19 and 20 , as evidenced by the longer N–N bond lengths and lower N–N bond-stretching vibrational frequencies.…”

Section: Chromium Dinitrogen Complexes Bearing Cyclopentadienyl and B...mentioning

confidence: 99%

“…Over the past 60 years, more than 600 terminal dinitrogen complexes characterized by X-ray crystallography have been reported. However, of them fewer than 50 terminal dinitrogen complexes (<8%) have been documented to be converted to diazenido and/or hydrazido complexes, and those reactions typically exhibit unsatisfactory yields . Because these transformations serve as the initial phase of the N 2 catalytic cycle, the observed low efficiency impedes the turnover of the catalytic N 2 reduction reaction. − …”

Section: Introductionmentioning

confidence: 99%

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Dinitrogen Activation and Functionalization Affording Chromium Diazenido and Hydrazido Complexes

Wang,

Yin,

Wei

et al. 2023

Acc. Chem. Res.

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Conspectus The activation and functionalization of N2 to form nitrogen-element bonds have long posed challenges to industrial, biological, and synthetic chemists. The first transition-metal dinitrogen complex prepared by Allen and Senoff in 1965 provoked researchers to explore homogeneous N2 fixation. Despite intensive research in the last six decades, efficient and quantitative conversion of N2 to diazenido and hydrazido species remains problematic. Relative to a plethora of reactions to generate N2 complexes, their functionalization reactions are rather rare, and the yields are often unsatisfactory, emphasizing the need for systematic investigations of the reaction mechanisms. In this Account, we summarize our recent work on the synthesis, spectroscopic features, electronic structures, and reactivities of several Cr–N2 complexes. Initially, a series of dinuclear and trinuclear Cr(I)–N2 complexes bearing cyclopentadienyl-phosphine ligands were accessed. However, they cannot achieve N2 functionalization but undergo oxidative addition reactions with phenylsilane, azobenzene, and other unsaturated organic compounds at the low-valent Cr(I) centers rather than at the N2 unit. Further reduction of these Cr(I) complexes leads to the formation of more activated mononuclear Cr(0) bis-dinitrogen complexes. Remarkably, silylation of the cyclopentadienyl-phosphine Cr(0)–N2 complex with Me3SiCl afforded the first Cr hydrazido complex. This process follows the distal pathway to functionalize the Nβ atom twice, yielding an end-on η1-hydrazido complex, Cr(III)N–N(SiMe3)2. In contrast, upon substitution of the phosphine ligand in the Cr(0)–N2 complex with a N-heterocyclic carbene (NHC) ligand, the corresponding reaction with Me3SiCl proceeds via the alternating pathway; the silylation occurs at both Nα and Nβ atoms and generates a side-on η2-hydrazido complex, Cr(III)(η2-Me3SiN–NSiMe3). Both silylation reactions are inevitably accompanied by the formation of Cr(III) hydrazido complexes and Cr(II) chlorides with a 2:1 ratio. These processes exhibit a peculiar ′3-4-2-1′ stoichiometry (i.e., treating 3 equiv of Cr(0)–N2 complexes with 4 equiv of Me3SiCl yields 2 equiv of Cr(III) disilyl-hydrazido complexes and 1 equiv of Cr(II) chloride). Upon replacing the monodentate phosphine and/or NHC ligand with a bisphosphine ligand, a monodinitrogen Cr(0) complex, instead of the bis-dinitrogen Cr(0) complexes, is obtained; consequently, the silylation reactions progress via the normal two-electron route, which passes through Cr(II)–NN–R diazenido species as an intermediate and furnishes [Cr(IV)N–NR2]+ hydrazido as the final products. More importantly, this type of Cr(0)–N2 complex can be not only silylated but also protonated and alkylated proficiently. All of the second-order reaction rates of the first and second transformations are determined along with the lifetimes of the intervening diazenido species. Based on these findings, we have successfully carried out nearly quantitative preparations of the Cr(IV) hydrazido species with unm...

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Section: Chromium Dinitrogen Complexes Bearing Cyclopentadienyl and B...mentioning

confidence: 92%

Section: Chromium Dinitrogen Complexes Bearing Cyclopentadienyl and B...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dinitrogen Activation and Functionalization Affording Chromium Diazenido and Hydrazido Complexes

Wang,

Yin,

Wei

et al. 2023

Acc. Chem. Res.

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“…[27] Quite recently, Xi and coworkers reported the stepwise functionalization of N 2 ligand on an anionic chromium complex bearing Cp* ligand K[Cp*Cr(depe)N 2 ] (Cp* = η 5 -C 5 Me 5 , depe = 1,2-bis(diethylphosphino)ethane) with MeOTf to give a cationic dimethyl hydrazide complex [Cp*Cr(depe)(= NNMe 2 )]OTf via a monomethyl diazenide complex [Cp*Cr(depe)(N=NMe)]. [28] In contrast to the addition of carbon-centered electrophiles to terminal N 2 ligand, Sellman and coworkers reported the reaction of a manganese-N 2 complex bearing a Cp ligand [Cp(CO) 2 Mn(N 2 )] (Cp = η 5 -C 5 H 5 ) with phenyl lithium (PhLi) as a carbon-centered nucleophile to form the anionic diazenide complex Li[Cp(CO) 2 Mn(NPh=N)]. [29] However, a recent study showed that the proposed reaction is unlikely to occur, and suggested that PhLi reacts with one of the CO ligands to provide an anionic acylcarbonyl dinitrogen complex Li[Cp-(CO)(N 2 )MnCOPh], then it decomposed to give an anionic phenyl complex Li[Cp(CO) 2 MnPh], which was misassigned in the original literature as the anionic diazenide complex with nitrogen-carbon bond.…”

Section: Stoichiometric Formation Of Nitrogen-carbon Bonds On Dinitro...mentioning

confidence: 99%

Direct Synthesis of Organonitrogen Compounds from Dinitrogen Using Transition Metal Complexes: Leap from Stoichiometric Reactions to Catalytic Reactions

Suginome,

Nishibayashi

2023

ChemCatChem

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Organonitrogen compounds are of vital importance to our lives. For almost all organonitrogen compounds, ammonia is only the feedstock as a nitrogen source. Ammonia is produced from dinitrogen (N2) and dihydrogen (H2) by the Haber‐Bosch process, which consumes an enormous amount of energy. As an alternative method to convert N2 into organonitrogen compounds under milder conditions, various stoichiometric reactions with transition metal complexes have been explored for the last 50 years. However, the field of catalytic formation of organonitrogen compounds directly from N2 with transition metal complexes is still in its infancy. This short review summarizes strategies to achieve the direct synthesis of organonitrogen compounds from N2 under mild reaction conditions using transition metal complexes ranging from stoichiometric reactions to catalytic reactions.

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“…[ 10‐13 ] Hence, a variety of strategies have been developed to achieve dinitrogen reduction more efficiently and in an environmentally‐friendly manner. [ 14‐37 ]…”

Section: Introductionmentioning

confidence: 99%

Light‐Driven Dinitrogen Activation with Transition Metal Complexes: Mechanisms and Applications^†

Zhao

Wei

2023

Chin. J. Chem.

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Comprehensive SummaryThe Haber‐Bosch process, which is used for ammonia (NH3) synthesis, requires vast amounts of energy, accounting for approximately 1%—2% of the world's annual energy consumption. Therefore, researchers in both industry and academia are interested in developing sustainable and environmentally friendly methods for synthesizing nitrogenous compounds at ambient conditions using renewable energy sources such as visible light. While several examples of thermal activation of dinitrogen molecules have been demonstrated using various transition metals and ligand frameworks, the use of light to weaken or split the strong N—N bond has been less explored. This article presents an overview of molecular complexes capable of dinitrogen photocleavage and provides mechanistic insights into the photoactivation process through experimental and theoretical studies. We believe this review will provide readers with an in‐depth understanding of the current state‐of‐the‐art and future research perspectives, particularly in the use of visible light for dinitrogen activation and transformation.

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Snapshots of Early-Stage Quantitative N₂ Electrophilic Functionalization

Cited by 11 publications

References 60 publications

Dinitrogen Activation and Functionalization Affording Chromium Diazenido and Hydrazido Complexes

Dinitrogen Activation and Functionalization Affording Chromium Diazenido and Hydrazido Complexes

Direct Synthesis of Organonitrogen Compounds from Dinitrogen Using Transition Metal Complexes: Leap from Stoichiometric Reactions to Catalytic Reactions

Light‐Driven Dinitrogen Activation with Transition Metal Complexes: Mechanisms and Applications^†

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Snapshots of Early-Stage Quantitative N2 Electrophilic Functionalization

Cited by 11 publications

References 60 publications

Dinitrogen Activation and Functionalization Affording Chromium Diazenido and Hydrazido Complexes

Dinitrogen Activation and Functionalization Affording Chromium Diazenido and Hydrazido Complexes

Direct Synthesis of Organonitrogen Compounds from Dinitrogen Using Transition Metal Complexes: Leap from Stoichiometric Reactions to Catalytic Reactions

Light‐Driven Dinitrogen Activation with Transition Metal Complexes: Mechanisms and Applications†

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Snapshots of Early-Stage Quantitative N₂ Electrophilic Functionalization

Light‐Driven Dinitrogen Activation with Transition Metal Complexes: Mechanisms and Applications^†