1
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Bhutto SM, Hooper RX, McWilliams SF, Mercado BQ, Holland PL. Iron(iv) alkyl complexes: electronic structure contributions to Fe-C bond homolysis and migration reactions that form N-C bonds from N 2. Chem Sci 2024; 15:3485-3494. [PMID: 38455018 PMCID: PMC10915813 DOI: 10.1039/d3sc05939a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 01/16/2024] [Indexed: 03/09/2024] Open
Abstract
High-valent iron alkyl complexes are rare, as they are prone to Fe-C bond homolysis. Here, we describe an unusual way to access formally iron(iv) alkyl complexes through double silylation of iron(i) alkyl dinitrogen complexes to form an NNSi2 group. Spectroscopically validated computations show that the disilylehydrazido(2-) ligand stabilizes the formal iron(iv) oxidation state through a strongly covalent Fe-N π-interaction, in which one π-bond fits an "inverted field" description. This means that the two bonding electrons are localized more on the metal than the ligand, and thus an iron(ii) resonance structure is a significant contributor, similar to the previously-reported phenyl analogue. However, in contrast to the phenyl complex which has an S = 1 ground state, the ground state of the alkyl complex is S = 2, which places one electron in the π* orbital, leading to longer and weaker Fe-N bonds. The reactivity of these hydrazido(2-) complexes is dependent on the steric and electronic properties of the specific alkyl group. When the alkyl group is the bulky trimethylsilylmethyl, the formally iron(iv) species is stable at room temperature and no migration of the alkyl ligand is observed. However, the analogous complex with the smaller methyl ligand does indeed undergo migration of the carbon-based ligand to the NNSi2 group to form a new N-C bond. This migration is followed by isomerization of the hydrazido ligand, and the product exists as two isomers that have distinct η1 and η2 binding of the hydrazido group. Lastly, when the alkyl group is benzyl, the Fe-C bond homolyzes to give a three-coordinate hydrazido(2-) complex which is likely due to the greater stability of a benzyl radical compared to that for methyl or trimethylsilylmethyl. These studies demonstrate the availability of a hydrocarbyl migration pathway at formally iron(iv) centers to form new N-C bonds directly to N2, though product selectivity is highly dependent on the identity of the migrating group.
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Affiliation(s)
- Samuel M Bhutto
- Department of Chemistry, Yale University New Haven Connecticut 06520 USA
| | - Reagan X Hooper
- Department of Chemistry, Yale University New Haven Connecticut 06520 USA
| | - Sean F McWilliams
- Department of Chemistry, Yale University New Haven Connecticut 06520 USA
| | - Brandon Q Mercado
- Department of Chemistry, Yale University New Haven Connecticut 06520 USA
| | - Patrick L Holland
- Department of Chemistry, Yale University New Haven Connecticut 06520 USA
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2
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Zapata-Rivera J, Calzado CJ. Dinitrogen Activation Mediated by the (P 2P Ph)Fe Complex: Electronic Structure, Dimerization Mechanism, and Magnetic Coupling. Inorg Chem 2024; 63:1633-1641. [PMID: 38194669 PMCID: PMC10954229 DOI: 10.1021/acs.inorgchem.3c03813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 12/18/2023] [Accepted: 12/22/2023] [Indexed: 01/11/2024]
Abstract
Herein, we report the estimation of the extent of dinitrogen activation by different charged and structural forms of (P2PPh)Fe biomimetic catalysts, which, in the presence of light, exhibit significant yield in the N2-to-NH3 conversion. Complete active space self-consistent field (CASSCF) calculations have been used to determine the electronic structure of different reduced forms of the mononuclear complexes: the neutral (P2PPh)Fe(N2)2 adduct and the anionic [(P2PPh)Fe(N2)]- and [(P2PPh)Fe(N2)]2- complexes. These calculations also revealed that the extent of reduction of a dinitrogen molecule reaches up to one electron (N21-) due to the back-bonding from the Fe center, in agreement with the changes observed in the vibration frequency of the N-N bond in these complexes. In addition, the energy profile of the dimerization of the mononuclear (P2PPh)Fe(N2)2 complex to the dinuclear mono-N2-bridged [(P2PPh)Fe]2(μ-N2) complex has been determined by means of density functional theory (DFT) calculations. A three-step mechanism has been proposed for the dimerization, favored by both kinetics and thermodynamics criteria. Finally, the magnetic coupling constant in the diiron (μ-N2) complex is estimated from CASSCF/NEVPT2 calculations. Such a dinuclear complex presents a strong antiferromagnetic coupling resulting from the interaction between two S = 1 d6 Fe2+ ions, bridged by a highly activated dinitrogen molecule (N22-) with two electrons on the π* orbitals.
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Affiliation(s)
- Jhon Zapata-Rivera
- Facultad
de Ciencias Naturales y Exactas, Departamento de Química, Universidad del Valle, Calle 13 N° 100–00, 25360 Cali, Colombia
| | - Carmen J. Calzado
- Departamento
de Química Física, Universidad
de Sevilla, c/Profesor
García González, s/n, 41012 Sevilla, Spain
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3
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Jori N, Keener M, Rajeshkumar T, Scopelliti R, Maron L, Mazzanti M. Dinitrogen cleavage by a dinuclear uranium(iii) complex. Chem Sci 2023; 14:13485-13494. [PMID: 38033909 PMCID: PMC10686047 DOI: 10.1039/d3sc05253b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 11/05/2023] [Indexed: 12/02/2023] Open
Abstract
Understanding the role of multimetallic cooperativity and of alkali ion-binding in the second coordination sphere is important for the design of complexes that can promote dinitrogen (N2) cleavage and functionalization. Herein, we compare the reaction products and mechanism of N2 reduction of the previously reported K2-bound dinuclear uranium(iii) complex, [K2{[UIII(OSi(OtBu)3)3]2(μ-O)}], B, with those of the analogous dinuclear uranium(iii) complexes, [K(2.2.2-cryptand)][K{UIII(OSi(OtBu)3)3}2(μ-O)], 1, and [K(2.2.2-cryptand)]2[{UIII(OSi(OtBu)3)3}2(μ-O)], 2, where one or two K+ ions have been removed from the second coordination sphere by addition of 2.2.2-cryptand. In this study, we found that the complete removal of the K+ ions from the inner coordination sphere leads to an enhanced reducing ability, as confirmed by cyclic voltammetry studies, of the resulting complex 2, and yields two new species upon N2 addition, namely the U(iii)/U(iv) complex, [K(2.2.2-cryptand)][{UIII(OSi(OtBu)3)3}(μ-O){UIV(OSi(OtBu)3)3}], 3, and the N2 cleavage product, the bis-nitride, terminal-oxo complex, [K(2.2.2-cryptand)]2[{UV(OSi(OtBu)3)3}(μ-N)2{UVI(OSi(OtBu)3)2(κ-O)}], 4. We propose that the formation of these two products involves a tetranuclear uranium-N2 intermediate that can only form in the absence of coordinated alkali ions, resulting in a six-electron transfer and cleavage of N2, demonstrating the possibility of a three-electron transfer from U(iii) to N2. These results give an insight into the relationship between alkali ion binding modes, multimetallic cooperativity and reactivity, and demonstrate how these parameters can be tuned to cleave and functionalize N2.
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Affiliation(s)
- Nadir Jori
- Insititut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Megan Keener
- Insititut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Thayalan Rajeshkumar
- Laboratoire de Physique et Chimie des Nano-objets, Institut National des Sciences Appliquées 31077 Toulouse Cedex 4 France
| | - Rosario Scopelliti
- X-Ray Diffraction and Surface Analytics Platform, Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL) CH-1015 Lausanne Switzerland
| | - Laurent Maron
- Laboratoire de Physique et Chimie des Nano-objets, Institut National des Sciences Appliquées 31077 Toulouse Cedex 4 France
| | - Marinella Mazzanti
- Insititut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
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4
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Bhardwaj A, Mondal B. μ 2 -η 1 :η 1 -N 2 Bridged Bimetallic Dinitrogen Complexes: Geometry of the First Excited State in Connection to N 2 π-Photoactivation. Chemistry 2023; 29:e202301984. [PMID: 37578813 DOI: 10.1002/chem.202301984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 08/08/2023] [Accepted: 08/14/2023] [Indexed: 08/15/2023]
Abstract
Bimetallic end-on μ2 -η1 :η1 -N2 bridging dinitrogen complexes have served as the platform for photochemical N2 activation, mainly for the N-N cleavage. However, the alternate N-N π-photoactivation route has remained largely unexplored. This study strengthens the notion of weakening the N-N bond through the population of π* orbital upon electronic excitation from the ground to the first excited state using four prototypical complexes based on Fe (1), Mo (2), and Ru (3,4). The complexes 1-4 possess characteristic N-N π* based LUMO (π*-π*-π*) centered on their M-N-N-M core, which was earlier postulated to play a central role in the N2 photoactivation. Vertical electronic excitation of the highest oscillator strength involves transitions to the N-N π*-based acceptor orbital (π*-π*-π*) in complexes 1-4. This induces geometry relaxation of the first excited metal-to-nitrogen (π*) charge transfer (1 MNCT) state leading to a "zigzag" M-N-N-M core in the equilibrium structure. Obtaining the equilibrium geometry in the first excited state with the full-sized complexes widens the scope of N-N π-photoactivation with μ2 -η1 :η1 -N2 bridging dinitrogen complexes. Promisingly, the elongated N-N bond and bent ∠MNN angle in the photoexcited S1 state of 1-4 resemble their radical- and di-anion forms, which lead toward thermodynamically feasible N-N protonation in the S1 excited state.
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Affiliation(s)
- Akhil Bhardwaj
- School of Chemical Sciences, Indian Institute of Technology Mandi, Himachal, Pradesh, 175075, India
| | - Bhaskar Mondal
- School of Chemical Sciences, Indian Institute of Technology Mandi, Himachal, Pradesh, 175075, India
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5
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Wang GX, Yin ZB, Wei J, Xi Z. Dinitrogen Activation and Functionalization Affording Chromium Diazenido and Hydrazido Complexes. Acc Chem Res 2023; 56:3211-3222. [PMID: 37937752 PMCID: PMC10666292 DOI: 10.1021/acs.accounts.3c00476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 10/01/2023] [Accepted: 10/18/2023] [Indexed: 11/09/2023]
Abstract
ConspectusThe 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 unmixed or hybrid substituents.The studies of Cr-N2 systems provide effective approaches for the activation and functionalization of N2, deepening the understanding of N2 electrophilic attack. We hope that this Account will inspire more discoveries related to the transformation of gaseous N2 to high-value-added nitrogen-containing organic compounds.
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Affiliation(s)
- Gao-Xiang Wang
- Beijing National Laboratory
for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry
and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Zhu-Bao Yin
- Beijing National Laboratory
for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry
and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Junnian Wei
- Beijing National Laboratory
for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry
and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Zhenfeng Xi
- Beijing National Laboratory
for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry
and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
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6
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Wang GX, Wang X, Jiang Y, Chen W, Shan C, Zhang P, Wei J, Ye S, Xi Z. Snapshots of Early-Stage Quantitative N 2 Electrophilic Functionalization. J Am Chem Soc 2023; 145:9746-9754. [PMID: 37067517 DOI: 10.1021/jacs.3c01497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
Electrophilic functionalization of N2 moieties in metal dinitrogen complexes typically initiates the catalytic synthesis of N-containing molecules directly from N2. Despite intensive research in the last six decades, how to efficiently and even quantitatively convert N2 into diazenido and hydrazido species still poses a great challenge. In this regard, systematic and comprehensive investigations to elucidate the reaction intricacies are of profound significance. Herein, we report a kinetic dissection on the first and second electrophilic functionalization steps of a new Cr0-N2 system with HOTf, MeOTf, and Me3SiOTf. All reactions pass through fleeting diazenido intermediates and furnish long-lived final hydrazido products, and both steps are quantitative conversions at low temperatures. All of the second-order reaction rates of the first and second transformations were determined as well as the lifetimes of the intervening diazenido species. Based on these findings, we succeeded in large-scale and near-quantitative preparation of all hydrazido species.
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Affiliation(s)
- Gao-Xiang Wang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Xueli Wang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Yang Jiang
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Wang Chen
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chunxiao Shan
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Peng Zhang
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Junnian Wei
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Shengfa Ye
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Zhenfeng Xi
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
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7
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Bhutto SM, Hooper RX, Mercado BQ, Holland PL. Mechanism of Nitrogen-Carbon Bond Formation from Iron(IV) Disilylhydrazido Intermediates during N 2 Reduction. J Am Chem Soc 2023; 145:4626-4637. [PMID: 36794981 DOI: 10.1021/jacs.2c12382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
We recently reported a reaction sequence that activates C-H bonds in simple arenes as well as the N-N triple bond in N2, delivering the aryl group to N2 to form a new N-C bond (Nature 2020, 584, 221). This enables the transformation of abundant feedstocks (arenes and N2) into N-containing organic compounds. The key N-C bond forming step occurs upon partial silylation of N2. However, the pathway through which reduction, silylation, and migration occurred was unknown. Here, we describe synthetic, structural, magnetic, spectroscopic, kinetic, and computational studies that elucidate the steps of this transformation. N2 must be silylated twice at the distal N atom before aryl migration can occur, and sequential silyl radical and silyl cation addition is a kinetically competent pathway to a formally iron(IV)-NN(SiMe3)2 intermediate that can be isolated at low temperature. Kinetic studies show its first-order conversion to the migrated product, and DFT calculations indicate a concerted transition state for migration. The electronic structure of the formally iron(IV) intermediate is examined using DFT and CASSCF calculations, which reveal contributions from iron(II) and iron(III) resonance forms with oxidized NNSi2 ligands. The depletion of electron density from the Fe-coordinated N atom makes it electrophilic enough to accept the incoming aryl group. This new pathway for the N-C bond formation offers a method for functionalizing N2 using organometallic chemistry.
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Affiliation(s)
- Samuel M Bhutto
- Department of Chemistry, Yale University, 225 Prospect St., New Haven, Connecticut 06520, United States
| | - Reagan X Hooper
- Department of Chemistry, Yale University, 225 Prospect St., New Haven, Connecticut 06520, United States
| | - Brandon Q Mercado
- Department of Chemistry, Yale University, 225 Prospect St., New Haven, Connecticut 06520, United States
| | - Patrick L Holland
- Department of Chemistry, Yale University, 225 Prospect St., New Haven, Connecticut 06520, United States
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8
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Yin ZB, Wu B, Wang GX, Wei J, Xi Z. Dinitrogen Functionalization Affording Chromium Diazenido and Side-on η 2-Hydrazido Complexes. J Am Chem Soc 2023; 145:7065-7070. [PMID: 36815758 DOI: 10.1021/jacs.3c00266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Isolation of key intermediate complexes in dinitrogen functionalization is crucial for elucidating the mechanistic details and further investigation. Herein, the synthesis and characterization of (μ-η1:η1-N2)(η1-N2)-Cr(I) 3 and (η1-N2)2-Cr(0) complexes 4 supported by Cp* (Cp* = C5Me5) and NHC ligands were reported. Further functionalization of Cr(0)-N2 complex 4 with silyl halides delivered the key intermediates in the alternating pathway, the chromium diazenido complex 5 and the chromium side-on η2-hydrazido complex 6. Protonation of 6 led to the quantitative formation of N2H4. Moreover, the [η2-Me3SiNNSiMe3]2- unit in 6 enabled N-C bond formation reactions with CO2 and tBuNCO, giving the corresponding N,O-chelating hydrazidochromium complexes 7 and 8, respectively.
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Affiliation(s)
- Zhu-Bao Yin
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Botao Wu
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Gao-Xiang Wang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Junnian Wei
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Zhenfeng Xi
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China.,State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Shanghai, 200032, China
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9
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Pokhriyal D, Heins SP, Sifri RJ, Gentekos DT, Coleman RE, Wolczanski PT, Cundari TR, Fors BP, Lancaster KM, MacMillan SN. Reversible C-C Bond Formation, Halide Abstraction, and Electromers in Complexes of Iron Containing Redox-Noninnocent Pyridine-imine Ligands. Inorg Chem 2021; 60:18662-18673. [PMID: 34889590 DOI: 10.1021/acs.inorgchem.1c01815] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The exploration of pyridine-imine (PI) iron complexes that exhibit redox noninnocence (RNI) led to several interesting discoveries. The reduction of (PI)FeX2 species afforded disproportionation products such as (dmpPI)2FeX (dmp = 2,6-Me2-C6H3, X = Cl, Br; 8-X) and (dippPI)2FeX (dipp = 2,6-iPr2-C6H3, X = Cl, Br; 9-X), which were independently prepared by reductions of (PI)FeX2 in the presence of PI. The crystal structure of 8-Br possessed an asymmetric unit with two distinct electromers, species with different electronic GSs: a low-spin (S = 1/2) configuration derived from an intermediate-spin S = 1 core antiferromagnetically (AF) coupled to an S = 1/2 PI ligand, and an S = 3/2 center resulting from a high-spin S = 2 core AF-coupled to an S = 1/2 PI ligand. Calculations were used to energetically compare plausible ground states. Polydentate diazepane-PI (DHPI) ligands were applied to the synthesis of monomeric dihalides (DHPI)FeX2 (X = Cl, 1-Cl2; X = Br, 1-Br2); reduction generated the highly distorted bioctahedral dimers (DHPA)2Fe2X2 ((3-X)2) containing a C-C bond formed from imine coupling; the monomers 1-X2 could be regenerated upon Ph3CX oxidation. Dihalides and their reduced counterparts were subjected to various alkyl halides and methyl methacrylate (MMA), generating polymers with little to no molecular weight control, indicative of simple radical-initiated polymerization.
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Affiliation(s)
- Devika Pokhriyal
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York, 14853, United States
| | - Spencer P Heins
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York, 14853, United States
| | - Renee J Sifri
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York, 14853, United States
| | - Dillon T Gentekos
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York, 14853, United States
| | - Rachael E Coleman
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York, 14853, United States
| | - Peter T Wolczanski
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York, 14853, United States
| | - Thomas R Cundari
- Department of Chemistry, CASCaM, University of North Texas, Denton, Texas 76201, United States
| | - Brett P Fors
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York, 14853, United States
| | - Kyle M Lancaster
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York, 14853, United States
| | - Samantha N MacMillan
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York, 14853, United States
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10
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Devi L, Kuzhalmozhi Madarasi P, Christopher Jeyakumar T. Computational studies of adsorption of dinitrogen over the group 8 metal-borazine complexes. CHEMICAL PAPERS 2021. [DOI: 10.1007/s11696-021-01953-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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11
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Bae DY, Lee G, Lee E. Fixation of Dinitrogen at an Asymmetric Binuclear Titanium Complex. Inorg Chem 2021; 60:12813-12822. [PMID: 34492761 DOI: 10.1021/acs.inorgchem.1c01050] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A new type of dititanium dinitrogen complex supported by a triphenolamine (TPA) ligand is reported. Analysis by single-crystal X-ray diffraction and Raman and NMR spectroscopy reveals different coordination geometries for the two titanium centers. Hence, coordination of TPA and a nitrogen ligand results in trigonal-bipyramidal geometry, while an octahedral titanium center is obtained upon additional coordination of an ethoxide generated upon C-O bond cleavage in a diethyl ether solvent molecule. The titanium complex successfully generates ammonia in the presence of an excess amount of PCy3HI and KC8 in 154% yield (per titanium atom). A titanium complex with a bulkier TPA does not form a dinitrogen complex, and mononuclear titanium dinitrogen complexes were not accessible, presumably because of the high tendency of early transition metals to form binuclear dinitrogen complexes.
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Affiliation(s)
- Dae Young Bae
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Gunhee Lee
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Eunsung Lee
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
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12
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Liang Q, DeMuth JC, Radović A, Wolford NJ, Neidig ML, Song D. [2Fe-2S] Cluster Supported by Redox-Active o-Phenylenediamide Ligands and Its Application toward Dinitrogen Reduction. Inorg Chem 2021; 60:13811-13820. [PMID: 34043353 DOI: 10.1021/acs.inorgchem.1c00683] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
As prevalent cofactors in living organisms, iron-sulfur clusters participate in not only the electron-transfer processes but also the biosynthesis of other cofactors. Many synthetic iron-sulfur clusters have been used in model studies, aiming to mimic their biological functions and to gain mechanistic insight into the related biological systems. The smallest [2Fe-2S] clusters are typically used for one-electron processes because of their limited capacity. Our group is interested in functionalizing small iron-sulfur clusters with redox-active ligands to enhance their electron storage capacity, because such functionalized clusters can potentially mediate multielectron chemical transformations. Herein we report the synthesis, structural characterization, and catalytic activity of a diferric [2Fe-2S] cluster functionalized with two o-phenylenediamide ligands. The electrochemical and chemical reductions of such a cluster revealed rich redox chemistry. The functionalized diferric cluster can store up to four electrons reversibly, where the first two reduction events are ligand-based and the remainder metal-based. The diferric [2Fe-2S] cluster displays catalytic activity toward silylation of dinitrogen, affording up to 88 equiv of the amine product per iron center.
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Affiliation(s)
- Qiuming Liang
- Davenport Chemical Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Joshua C DeMuth
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Aleksa Radović
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Nikki J Wolford
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Michael L Neidig
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Datong Song
- Davenport Chemical Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
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13
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Forrest SJK, Schluschaß B, Yuzik-Klimova EY, Schneider S. Nitrogen Fixation via Splitting into Nitrido Complexes. Chem Rev 2021; 121:6522-6587. [DOI: 10.1021/acs.chemrev.0c00958] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sebastian J. K. Forrest
- Institut für Anorganische Chemie, Universität Göttingen, Tammannstrasse 4, D-37077 Göttingen, Germany
| | - Bastian Schluschaß
- Institut für Anorganische Chemie, Universität Göttingen, Tammannstrasse 4, D-37077 Göttingen, Germany
| | | | - Sven Schneider
- Institut für Anorganische Chemie, Universität Göttingen, Tammannstrasse 4, D-37077 Göttingen, Germany
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14
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Wedal JC, Windorff CJ, Huh DN, Ryan AJ, Ziller JW, Evans WJ. Structural variations in cyclopentadienyl uranium(III) iodide complexes. J COORD CHEM 2020. [DOI: 10.1080/00958972.2020.1856824] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Justin C. Wedal
- Department of Chemistry, University of California, Irvine, CA, USA
| | - Cory J. Windorff
- Department of Chemistry, University of California, Irvine, CA, USA
| | - Daniel N. Huh
- Department of Chemistry, University of California, Irvine, CA, USA
| | - Austin J. Ryan
- Department of Chemistry, University of California, Irvine, CA, USA
| | - Joseph W. Ziller
- Department of Chemistry, University of California, Irvine, CA, USA
| | - William J. Evans
- Department of Chemistry, University of California, Irvine, CA, USA
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15
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Arnett CH, Bogacz I, Chatterjee R, Yano J, Oyala PH, Agapie T. Mixed-Valent Diiron μ-Carbyne, μ-Hydride Complexes: Implications for Nitrogenase. J Am Chem Soc 2020; 142:18795-18813. [PMID: 32976708 DOI: 10.1021/jacs.0c05920] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Binding of N2 by the FeMo-cofactor of nitrogenase is believed to occur after transfer of 4 e- and 4 H+ equivalents to the active site. Although pulse EPR studies indicate the presence of two Fe-(μ-H)-Fe moieties, the structural and electronic features of this mixed valent intermediate remain poorly understood. Toward an improved understanding of this bioorganometallic cluster, we report herein that diiron μ-carbyne complex (P6ArC)Fe2(μ-H) can be oxidized and reduced, allowing for the first time spectral characterization of two EPR-active Fe(μ-C)(μ-H)Fe model complexes linked by a 2 e- transfer which bear some resemblance to a pair of En and En+2 states of nitrogenase. Both species populate S = 1/2 states at low temperatures, and the influence of valence (de)localization on the spectroscopic signature of the μ-hydride ligand was evaluated by pulse EPR studies. Compared to analogous data for the {Fe2(μ-H)}2 state of FeMoco (E4(4H)), the data and analysis presented herein suggest that the hydride ligands in E4(4H) bridge isovalent (most probably FeIII) metal centers. Although electron transfer involves metal-localized orbitals, investigations of [(P6ArC)Fe2(μ-H)]+1 and [(P6ArC)Fe2(μ-H)]-1 by pulse EPR revealed that redox chemistry induces significant changes in Fe-C covalency (-50% upon 2 e- reduction), a conclusion further supported by X-ray absorption spectroscopy, 57Fe Mössbauer studies, and DFT calculations. Combined, our studies demonstrate that changes in covalency buffer against the accumulation of excess charge density on the metals by partially redistributing it to the bridging carbon, thereby facilitating multielectron transformations.
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Affiliation(s)
- Charles H Arnett
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Isabel Bogacz
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Ruchira Chatterjee
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Junko Yano
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Paul H Oyala
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Theodor Agapie
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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16
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Abstract
A persistent challenge in chemistry is to activate abundant, yet inert molecules such as hydrocarbons and atmospheric N2. In particular, forming C–N bonds from N2 typically requires a reactive organic precursor1, which limits the ability to design catalytic cycles. Here, we report an diketiminate-supported iron system that is able to sequentially activate benzene and N2 to form aniline derivatives. The key to this new coupling reaction is the partial silylation of a reduced iron-N2 complex, which is followed by migratory insertion of a benzene-derived phenyl group to the nitrogen. Further reduction releases the nitrogen products, and the resulting iron species can re-enter the cyclic pathway. Using a mixture of sodium powder, crown ether, and trimethylsilyl bromide, an easily prepared diketiminate iron bromide complex2 can mediate the one-pot conversion of several petroleum-derived compounds into the corresponding silylated aniline derivatives using N2 as the nitrogen source. Numerous compounds along the cyclic pathway have been isolated and crystallographically characterized; their reactivity outlines the mechanism including the hydrocarbon activation step and the N2 functionalization step. This strategy incorporates nitrogen atoms from N2 directly into abundant hydrocarbons.
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17
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Chalkley MJ, Drover MW, Peters JC. Catalytic N 2-to-NH 3 (or -N 2H 4) Conversion by Well-Defined Molecular Coordination Complexes. Chem Rev 2020; 120:5582-5636. [PMID: 32352271 DOI: 10.1021/acs.chemrev.9b00638] [Citation(s) in RCA: 178] [Impact Index Per Article: 44.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Nitrogen fixation, the six-electron/six-proton reduction of N2, to give NH3, is one of the most challenging and important chemical transformations. Notwithstanding the barriers associated with this reaction, significant progress has been made in developing molecular complexes that reduce N2 into its bioavailable form, NH3. This progress is driven by the dual aims of better understanding biological nitrogenases and improving upon industrial nitrogen fixation. In this review, we highlight both mechanistic understanding of nitrogen fixation that has been developed, as well as advances in yields, efficiencies, and rates that make molecular alternatives to nitrogen fixation increasingly appealing. We begin with a historical discussion of N2 functionalization chemistry that traverses a timeline of events leading up to the discovery of the first bona fide molecular catalyst system and follow with a comprehensive overview of d-block compounds that have been targeted as catalysts up to and including 2019. We end with a summary of lessons learned from this significant research effort and last offer a discussion of key remaining challenges in the field.
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Affiliation(s)
- Matthew J Chalkley
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Marcus W Drover
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Jonas C Peters
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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18
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Toniolo D, Scopelliti R, Zivkovic I, Mazzanti M. Assembly of High-Spin [Fe 3] Clusters by Ligand-Based Multielectron Reduction. J Am Chem Soc 2020; 142:7301-7305. [PMID: 32248681 DOI: 10.1021/jacs.0c01664] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The hexanuclear [Na12Fe6(tris-cyclo-salophen)2(THF)14], 1-THF, and the trinuclear [Na6Fe3(tris-cyclo-salophen)(py)9], 1-py, Fe(II) clusters can be easily assembled in one step from the ligand-based reduction of the [FeII(salophen)(THF)] complex. These complexes consist of triangular cores where three Fe(II) ions are held together, within range of bonding interaction, by the hexa-amide, hexaphenolate macrocyclic ligand tris-cyclo-salophen12-. The tris-cyclo-salophen12- ligand is perfectly suited for binding three Fe(II) centers at short distances, allowing for strong magnetic coupling between the Fe(II) centers. The macrocyclic ligand is generated by the reductive coupling of the imino groups of three salophen ligands, resulting in three new C-C bonds. The six electrons stored in the ligand become available for the reduction of carbon dioxide with selective formation of carbonate.
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Affiliation(s)
- Davide Toniolo
- Insititut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Rosario Scopelliti
- Insititut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Ivica Zivkovic
- Laboratory for Quantum Magnetism, Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Marinella Mazzanti
- Insititut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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19
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Sorsche D, Miehlich ME, Searles K, Gouget G, Zolnhofer EM, Fortier S, Chen CH, Gau M, Carroll PJ, Murray CB, Caulton KG, Khusniyarov MM, Meyer K, Mindiola DJ. Unusual Dinitrogen Binding and Electron Storage in Dinuclear Iron Complexes. J Am Chem Soc 2020; 142:8147-8159. [DOI: 10.1021/jacs.0c01488] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Dieter Sorsche
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Matthias E. Miehlich
- Inorganic Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Keith Searles
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Department of Chemistry and Molecular Structure Center, Indiana University, Bloomington, Indiana 47405, United States
| | - Guillaume Gouget
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Eva M. Zolnhofer
- Inorganic Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Skye Fortier
- Department of Chemistry and Molecular Structure Center, Indiana University, Bloomington, Indiana 47405, United States
| | - Chun-Hsing Chen
- Department of Chemistry and Molecular Structure Center, Indiana University, Bloomington, Indiana 47405, United States
| | - Michael Gau
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Patrick J. Carroll
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Christopher B. Murray
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Kenneth G. Caulton
- Department of Chemistry and Molecular Structure Center, Indiana University, Bloomington, Indiana 47405, United States
| | - Marat M. Khusniyarov
- Inorganic Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Karsten Meyer
- Inorganic Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Daniel J. Mindiola
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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20
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Cha J, Kwon H, Song H, Lee E. Dinitrogen activation by a penta-pyridyl molybdenum complex. Dalton Trans 2020; 49:12945-12949. [DOI: 10.1039/d0dt02692a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A new dinitrogen (N2) molybdenum(0) complex supported exclusively by pyridine ligands was synthesized.
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Affiliation(s)
- Jeongmin Cha
- Department of Chemistry
- Pohang University of Science and Technology
- 37673 Pohang
- Republic of Korea
| | - Hyunchul Kwon
- Department of Chemistry
- Pohang University of Science and Technology
- 37673 Pohang
- Republic of Korea
| | - Hayoung Song
- Department of Chemistry
- Pohang University of Science and Technology
- 37673 Pohang
- Republic of Korea
| | - Eunsung Lee
- Department of Chemistry
- Pohang University of Science and Technology
- 37673 Pohang
- Republic of Korea
- Division of Advanced Materials Science
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21
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Nagelski AL, Fataftah MS, Bollmeyer MM, McWilliams SF, MacMillan SN, Mercado BQ, Lancaster KM, Holland PL. The influences of carbon donor ligands on biomimetic multi-iron complexes for N 2 reduction. Chem Sci 2020; 11:12710-12720. [PMID: 34094466 PMCID: PMC8163302 DOI: 10.1039/d0sc03447a] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The active site clusters of nitrogenase enzymes possess the only examples of carbides in biology. These are the only biological FeS clusters that are capable of reducing N2 to NH4+, implicating the central carbon and its interaction with Fe as important in the mechanism of N2 reduction. This biological question motivates study of the influence of carbon donors on the electronic structure and reactivity of unsaturated, high-spin iron centers. Here, we present functional and structural models that test the impacts of carbon donors and sulfide donors in simpler iron compounds. We report the first example of a diiron complex that is bridged by an alkylidene and a sulfide, which serves as a high-fidelity structural and spectroscopic model of a two-iron portion of the active-site cluster (FeMoco) in the resting state of Mo-nitrogenase. The model complexes have antiferromagnetically coupled pairs of high-spin iron centers, and sulfur K-edge X-ray absorption spectroscopy shows comparable covalency of the sulfide for C and S bridged species. The sulfur-bridged compound does not interact with N2 even upon reduction, but upon removal of the sulfide it becomes capable of reducing N2 to NH4+ with the addition of protons and electrons. This provides synthetic support for sulfide extrusion in the activation of nitrogenase cofactors. High-spin diiron alkylidenes give insight into the electronic structure and functional relevance of carbon in the FeMoco active site of nitrogenase.![]()
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Affiliation(s)
| | | | - Melissa M. Bollmeyer
- Department of Chemistry and Chemical Biology
- Baker Laboratory
- Cornell University
- Ithaca
- USA
| | | | - Samantha N. MacMillan
- Department of Chemistry and Chemical Biology
- Baker Laboratory
- Cornell University
- Ithaca
- USA
| | | | - Kyle M. Lancaster
- Department of Chemistry and Chemical Biology
- Baker Laboratory
- Cornell University
- Ithaca
- USA
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22
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Kokubo Y, Wasada‐Tsutsui Y, Yomura S, Yanagisawa S, Kubo M, Kugimiya S, Kajita Y, Ozawa T, Masuda H. Syntheses, Characterizations, and Crystal Structures of Dinitrogen‐Divanadium Complexes Bearing Triamidoamine Ligands. Eur J Inorg Chem 2019. [DOI: 10.1002/ejic.201901123] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Yoshiaki Kokubo
- Department of Applied Chemistry Faculty of Engineering Aichi Institute of Technology 1247 Yachigusa 470‐0392 Yakusa‐cho Toyota Japan
| | - Yuko Wasada‐Tsutsui
- Department of Life and Applied Chemistry Graduate School of Engineering Nagoya Institute of Technology 466‐8555 Nagoya Gokiso‐cho, Showa‐ku Japan
| | - Shunsuke Yomura
- Department of Life and Applied Chemistry Graduate School of Engineering Nagoya Institute of Technology 466‐8555 Nagoya Gokiso‐cho, Showa‐ku Japan
| | - Sachiko Yanagisawa
- Graduate School of Life Science Graduate School of Engineering University of Hyogo 3‐2‐1 Koto 678‐1297 Kamigori‐cho Ako‐gun Hyogo Japan
| | - Minoru Kubo
- Graduate School of Life Science Graduate School of Engineering University of Hyogo 3‐2‐1 Koto 678‐1297 Kamigori‐cho Ako‐gun Hyogo Japan
| | - Shinichi Kugimiya
- Department of Applied Chemistry Faculty of Engineering Aichi Institute of Technology 1247 Yachigusa 470‐0392 Yakusa‐cho Toyota Japan
| | - Yuji Kajita
- Department of Applied Chemistry Faculty of Engineering Aichi Institute of Technology 1247 Yachigusa 470‐0392 Yakusa‐cho Toyota Japan
| | - Tomohiro Ozawa
- Department of Life and Applied Chemistry Graduate School of Engineering Nagoya Institute of Technology 466‐8555 Nagoya Gokiso‐cho, Showa‐ku Japan
| | - Hideki Masuda
- Department of Applied Chemistry Faculty of Engineering Aichi Institute of Technology 1247 Yachigusa 470‐0392 Yakusa‐cho Toyota Japan
- Department of Life and Applied Chemistry Graduate School of Engineering Nagoya Institute of Technology 466‐8555 Nagoya Gokiso‐cho, Showa‐ku Japan
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23
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Hatanaka T, Kusunose H, Kawaguchi H, Funahashi Y. Dinitrogen Activation by a Heterometallic VFe Complex Derived from 1,1'‐Bis(arylamido)vanadocene. Eur J Inorg Chem 2019. [DOI: 10.1002/ejic.201901120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Tsubasa Hatanaka
- Department of Chemistry Graduate School of Science Osaka University 1–1 Machikaneyama 560–0043 Toyonaka Osaka Japan
| | - Hinano Kusunose
- Department of Chemistry Graduate School of Science Osaka University 1–1 Machikaneyama 560–0043 Toyonaka Osaka Japan
| | - Hiroyuki Kawaguchi
- Department of Chemistry Graduate School of Science Tokyo Institute of Technology 2–12–1 Ookayama, Meguro‐ku 152–8551 Tokyo Japan
| | - Yasuhiro Funahashi
- Department of Chemistry Graduate School of Science Osaka University 1–1 Machikaneyama 560–0043 Toyonaka Osaka Japan
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24
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Zhang Y, Wei J, Zhu M, Chi Y, Zhang W, Ye S, Xi Z. Tetralithio Metalla‐aromatics with Two Independent Perpendicular Dilithio Aromatic Rings Spiro‐fused by One Manganese Atom. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201904681] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Yongliang Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS)Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of EducationCollege of ChemistryPeking University Beijing 100871 P. R. China
| | - Junnian Wei
- Beijing National Laboratory for Molecular Sciences (BNLMS)Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of EducationCollege of ChemistryPeking University Beijing 100871 P. R. China
| | - Miaomiao Zhu
- Beijing National Laboratory for Molecular Sciences (BNLMS)Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of EducationCollege of ChemistryPeking University Beijing 100871 P. R. China
| | - Yue Chi
- Beijing National Laboratory for Molecular Sciences (BNLMS)Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of EducationCollege of ChemistryPeking University Beijing 100871 P. R. China
| | - Wen‐Xiong Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS)Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of EducationCollege of ChemistryPeking University Beijing 100871 P. R. China
| | - Shengfa Ye
- Max-Planck Institute for Coal Research 45470 Mülheim a. d. Ruhr Germany
| | - Zhenfeng Xi
- Beijing National Laboratory for Molecular Sciences (BNLMS)Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of EducationCollege of ChemistryPeking University Beijing 100871 P. R. China
- State Key Laboratory of Organometallic ChemistryShanghai Institute of Organic Chemistry Shanghai 200032 P. R. China
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25
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Zhang Y, Wei J, Zhu M, Chi Y, Zhang WX, Ye S, Xi Z. Tetralithio Metalla-aromatics with Two Independent Perpendicular Dilithio Aromatic Rings Spiro-fused by One Manganese Atom. Angew Chem Int Ed Engl 2019; 58:9625-9631. [PMID: 31102480 DOI: 10.1002/anie.201904681] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Indexed: 12/13/2022]
Abstract
Herein, we present the realization of a class of unprecedented aromatic structures 2: metalla-aromatics with two independent and perpendicular aromatic rings spiro-fused by a transition-metal spiro atom, of which their corresponding organic analogues are impossible. Tetralithio spiro manganacycles 2 are readily synthesized from 1,4-dilithio-1,3-butadienes 1 and MnCl2 in the presence of lithium. The aromaticity of 2 is supported by experimental measurements (X-ray structural analysis, NMR) and theoretical analyses (NICS, ACID, MOs). The spiro atom Mn in 2 uses its 3dxz and 3dxy orbitals to form the two perpendicular manganacycles, which are two independent 6π aromatic systems. Theoretical analyses reveal that the Li cations play an indispensable role in governing their geometric and electronic structures and hence their aromaticity. Therefore, this work contributes not only to enrich the concept of aromaticity, but also to deepen the understanding of the fundamental chemical bonding.
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Affiliation(s)
- Yongliang Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing, 100871, P. R. China
| | - Junnian Wei
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing, 100871, P. R. China
| | - Miaomiao Zhu
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing, 100871, P. R. China
| | - Yue Chi
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing, 100871, P. R. China
| | - Wen-Xiong Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing, 100871, P. R. China
| | - Shengfa Ye
- Max-Planck Institute for Coal Research, 45470, Mülheim a. d. Ruhr, Germany
| | - Zhenfeng Xi
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing, 100871, P. R. China.,State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Shanghai, 200032, P. R. China
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26
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27
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Cheng J, Liu J, Leng X, Lohmiller T, Schnegg A, Bill E, Ye S, Deng L. A Two-Coordinate Iron(II) Imido Complex with NHC Ligation: Synthesis, Characterization, and Its Diversified Reactivity of Nitrene Transfer and C-H Bond Activation. Inorg Chem 2019; 58:7634-7644. [PMID: 31083985 PMCID: PMC6750749 DOI: 10.1021/acs.inorgchem.9b01147] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Iron
terminal imido species are typically implicated as reaction intermediates
in iron-catalyzed transformations. While a large body of work has
been devoted to mid- and high-valent iron imidos, to date the chemistry
of iron(II) imidos has remained largely unexplored due to the difficulty
in accessing them. Herein, we present a study on the two-coordinate
iron(II) imido complex [(IPr)Fe(NArTrip)] (3; IPr = 1,3-bis(2′,6′-diisopropylphenyl)imidazol-2-ylidene;
ArTrip = 2,6-bis(2′,4′,6′-triisopropylphenyl)phenyl)
prepared from the reaction of an iron(0) complex with the bulky azide
ArTripN3. Spectroscopic investigations in combination
with DFT calculations established a high-spin S =
2 ground spin state for 3, consistent with its long Fe–N
multiple bond of 1.715(2) Å revealed by X-ray diffraction analysis.
Complex 3 exhibits unusual activity of nitrene transfer
and C–H bond activation in comparison to the reported iron
imido complexes. Specifically, the reactions of 3 with
CH2=CHArCF3, an electron-deficient alkene,
and CO, a strong π acid, readily afford nitrene transfer products,
ArCF3CH=CHNHArTrip and ArTripNCO, respectively, yet no similar reaction occurs when 3 is treated with electron-rich alkenes and PMe3. Moreover, 3 is inert toward the weak C(sp3)–H bonds
in 1,4-cyclohexadiene, THF, and toluene, whereas it can cleave the
stronger C(sp)–H bond in p-trifluoromethylphenylacetylene
to form an iron(II) amido alkynyl complex. Interestingly, intramolecular
C(sp3)–H bond functionalization was observed by
adding (p-Tol)2CN2 to 3. The unique reactivity of 3 is attributed to
its low-coordinate nature and the high negative charge population
on the imido N atom, which render its iron–imido unit nucleophilic
in nature. The two-coordinate iron(II)
imido complex (IPr)Fe(NArTrip) (3) exhibits
a high-spin ground state (S = 2) and was found to
be reactive toward electron-deficient alkene, diazo compounds, terminal
alkyne, et al., in which diversified reactivities of nitrene transfer,
C−H bond activation, and C−N bond formation have been
observed. The reactivity pattern reflects the nucleophilic nature
of the imido moiety of the high-spin iron(II) complex.
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Affiliation(s)
- Jun Cheng
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis , Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences , 345 Lingling Road , Shanghai 200032 , People's Republic of China
| | - Jian Liu
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis , Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences , 345 Lingling Road , Shanghai 200032 , People's Republic of China
| | - Xuebing Leng
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis , Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences , 345 Lingling Road , Shanghai 200032 , People's Republic of China
| | - Thomas Lohmiller
- Berlin Joint EPR Lab , Helmholtz-Zentrum Berlin für Materialien und Energie , Berlin , Germany
| | - Alexander Schnegg
- Max-Planck-Institut für Chemische Energiekonversion , Mülheim an der Ruhr D-45470 , Germany
| | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion , Mülheim an der Ruhr D-45470 , Germany
| | - Shengfa Ye
- Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1 , Mülheim an der Ruhr D-45470 , Germany
| | - Liang Deng
- State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis , Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences , 345 Lingling Road , Shanghai 200032 , People's Republic of China
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28
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Ahn S, Hong M, Sundararajan M, Ess DH, Baik MH. Design and Optimization of Catalysts Based on Mechanistic Insights Derived from Quantum Chemical Reaction Modeling. Chem Rev 2019; 119:6509-6560. [DOI: 10.1021/acs.chemrev.9b00073] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Seihwan Ahn
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea
| | - Mannkyu Hong
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea
| | - Mahesh Sundararajan
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea
| | - Daniel H. Ess
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602, United States
| | - Mu-Hyun Baik
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea
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29
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Schild DJ, Peters JC. Light Enhanced Fe-Mediated Nitrogen Fixation: Mechanistic Insights Regarding H 2 Elimination, HER, and NH 3 Generation. ACS Catal 2019; 9:4286-4295. [PMID: 31467770 DOI: 10.1021/acscatal.9b00523] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Despite their proposed accumulation at the Fe sites of the FeMo-cofactor of MoFe-nitrogenase, the presence of hydride ligands in molecular model systems capable of the nitrogen reduction reaction (N2RR) appears to diminish the catalytic N2-to-NH3 conversion. We find that for an iron-based system bearing the trisphosphine ligand P2PPh, a dramatic difference in yields is observed for N2RR catalyzed by precatalysts with zero, one, or two hydride ligands; however, irradiating the three different catalysts with a mercury lamp results in similar yields. Although the efficacy for N2RR versus the hydrogen evolution reaction (HER) is modest for this system by comparison to certain iron (and other metal) catalysts, the system provides an opportunity to study the role of hydrides in the selectivity for N2RR versus HER, which is a central issue in catalyst design. Stochiometric reactions with hydride containing precatalysts reveal a hydrogen evolution cycle in which no nitrogen fixation occurs. Irradiation of the dihydride precatalysts, observed during turnover, results in H2 elimination and formation of (P2PPh)Fe(N2)2, which itself is unreactive with acids at low temperature. N2 functionalization does occur with acids and silyl electrophiles for the reduced species [(P2PPh)Fe(N2)]- and [(P2PPh)Fe(N2)]2-, which have been characterized independently. The requirement of accessing such low formal oxidation states explains the need for strong reductants. The low selectivity of the system for functionalization at Nβ versus Fe creates off-path hydride species that participate in unproductive HER, helping to explain the low selectivity for N2RR over HER. The data presented here hence lends further insight into the growing understanding of the selectivity, activity, and required driving force relevant to iron (and other) N2RR catalysts.
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Affiliation(s)
- Dirk J. Schild
- Division of Chemistry and Chemical Engineering, California Institute of Technology (Caltech), Pasadena, California 91125, United States
| | - Jonas C. Peters
- Division of Chemistry and Chemical Engineering, California Institute of Technology (Caltech), Pasadena, California 91125, United States
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30
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Thompson NB, Oyala PH, Dong HT, Chalkley MJ, Zhao J, Alp EE, Hu M, Lehnert N, Peters JC. Electronic Structures of an [Fe(NNR 2)] +/0/- Redox Series: Ligand Noninnocence and Implications for Catalytic Nitrogen Fixation. Inorg Chem 2019; 58:3535-3549. [PMID: 30762355 DOI: 10.1021/acs.inorgchem.9b00133] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The intermediacy of metal-NNH2 complexes has been implicated in the catalytic cycles of several examples of transition-metal-mediated nitrogen (N2) fixation. In this context, we have shown that triphosphine-supported Fe(N2) complexes can be reduced and protonated at the distal N atom to yield Fe(NNH2) complexes over an array of charge and oxidation states. Upon exposure to further H+/e- equivalents, these species either continue down a distal-type Chatt pathway to yield a terminal iron(IV) nitride or instead follow a distal-to-alternating pathway resulting in N-H bond formation at the proximal N atom. To understand the origin of this divergent selectivity, herein we synthesize and elucidate the electronic structures of a redox series of Fe(NNMe2) complexes, which serve as spectroscopic models for their reactive protonated congeners. Using a combination of spectroscopies, in concert with density functional theory and correlated ab initio calculations, we evidence one-electron redox noninnocence of the "NNMe2" moiety. Specifically, although two closed-shell configurations of the "NNR2" ligand have been commonly considered in the literature-isodiazene and hydrazido(2-)-we provide evidence suggesting that, in their reduced forms, the present iron complexes are best viewed in terms of an open-shell [NNR2]•- ligand coupled antiferromagnetically to the Fe center. This one-electron redox noninnocence resembles that of the classically noninnocent ligand NO and may have mechanistic implications for selectivity in N2 fixation activity.
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Affiliation(s)
- Niklas B Thompson
- Division of Chemistry and Chemical Engineering , California Institute of Technology , Pasadena , California 91125 , United States
| | - Paul H Oyala
- Division of Chemistry and Chemical Engineering , California Institute of Technology , Pasadena , California 91125 , United States
| | - Hai T Dong
- Department of Chemistry and Department of Biophysics , University of Michigan , Ann Arbor , Michigan 48109-1055 , United States
| | - Matthew J Chalkley
- Division of Chemistry and Chemical Engineering , California Institute of Technology , Pasadena , California 91125 , United States
| | - Jiyong Zhao
- Advanced Photon Source (APS) , Argonne National Laboratory (ANL) , Argonne , Illinois 60439 , United States
| | - E Ercan Alp
- Advanced Photon Source (APS) , Argonne National Laboratory (ANL) , Argonne , Illinois 60439 , United States
| | - Michael Hu
- Advanced Photon Source (APS) , Argonne National Laboratory (ANL) , Argonne , Illinois 60439 , United States
| | - Nicolai Lehnert
- Department of Chemistry and Department of Biophysics , University of Michigan , Ann Arbor , Michigan 48109-1055 , United States
| | - Jonas C Peters
- Division of Chemistry and Chemical Engineering , California Institute of Technology , Pasadena , California 91125 , United States
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31
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Yin J, Li J, Wang GX, Yin ZB, Zhang WX, Xi Z. Dinitrogen Functionalization Affording Chromium Hydrazido Complex. J Am Chem Soc 2019; 141:4241-4247. [DOI: 10.1021/jacs.9b00822] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Jianhao Yin
- Beijing National Laboratory for Molecular
Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular
Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Jiapeng Li
- Beijing National Laboratory for Molecular
Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular
Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Gao-Xiang Wang
- Beijing National Laboratory for Molecular
Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular
Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Zhu-Bao Yin
- Beijing National Laboratory for Molecular
Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular
Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Wen-Xiong Zhang
- Beijing National Laboratory for Molecular
Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular
Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Zhenfeng Xi
- Beijing National Laboratory for Molecular
Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular
Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
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32
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Taylor LJ, Kays DL. Low-coordinate first-row transition metal complexes in catalysis and small molecule activation. Dalton Trans 2019; 48:12365-12381. [DOI: 10.1039/c9dt02402f] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this Perspective, we will highlight selected examples of transition metal complexes with low coordination numbers whose high reactivity has been exploited in catalysis and the activation of small molecules featuring strong bonds (N2, CO2, and CO).
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Affiliation(s)
| | - Deborah L. Kays
- School of Chemistry
- University of Nottingham
- University Park
- Nottingham
- UK
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33
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McWilliams SF, Bunting PC, Kathiresan V, Mercado BQ, Hoffman BM, Long JR, Holland PL. Isolation and characterization of a high-spin mixed-valent iron dinitrogen complex. Chem Commun (Camb) 2018; 54:13339-13342. [PMID: 30403226 DOI: 10.1039/c8cc07294a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report a rare example of a mixed-valence iron compound with an FeNNFe core, which gives insight into the structural, spectroscopic, and magnetic influences of single-electron reductions and oxidations. In the new compound, the odd electron is localized as judged from Mössbauer spectra at 80 K and infrared spectra at room temperature, and the backbonding into the N2 unit is intermediate between diiron(i) and diiron(0) congeners. Magnetic susceptibility and relaxation studies on the series of FeNNFe compounds show significant magnetic anisotropy, but through-barrier pathways enable fairly rapid magnetic relaxation.
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Affiliation(s)
- Sean F McWilliams
- Department of Chemistry, Yale University, 225 Prospect St., New Haven, CT 06520, USA.
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34
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Piascik AD, Li R, Wilkinson HJ, Green JC, Ashley AE. Fe-Catalyzed Conversion of N 2 to N(SiMe 3) 3 via an Fe-Hydrazido Resting State. J Am Chem Soc 2018; 140:10691-10694. [PMID: 30114921 DOI: 10.1021/jacs.8b06999] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The catalytic conversion of N2 to N(SiMe3)3 by homogeneous transition metal compounds is a rapidly developing field, yet few mechanistic details have been experimentally elucidated for 3 d element catalysts. Herein we show that Fe(PP)2(N2) (PP = R2PCH2CH2PR2; R = Me, 1Me; R = Et, 1Et) are highly effective for the catalytic production of N(SiMe3)3 from N2 (using KC8/Me3SiCl), with the yields being the highest reported to date for Fe-based catalysts. We propose that N2 fixation proceeds via electrophilic Nβ silylation and 1e- reduction to form unstable FeI(NN-SiMe3) intermediates, which disproportionate to 1Me/Et and hydrazido FeII[N-N(SiMe3)2] species (3Me/Et); the latter act as resting states on the catalytic cycle. Subsequent 2e- reduction of 3Me/Et leads to N-N scission and formation of [N(SiMe3)2]- and putative anionic Fe imido products. These mechanistic results are supported by both experiment and DFT calculations.
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Affiliation(s)
- Adam D Piascik
- Department of Chemistry , Imperial College London , Exhibition Road , South Kensington, London SW7 2AZ , United Kingdom
| | - Ruohao Li
- Department of Chemistry , Imperial College London , Exhibition Road , South Kensington, London SW7 2AZ , United Kingdom
| | - Harry J Wilkinson
- Department of Chemistry , Imperial College London , Exhibition Road , South Kensington, London SW7 2AZ , United Kingdom
| | - Jennifer C Green
- Inorganic Chemistry Laboratory , University of Oxford , South Parks Road , Oxford OX1 3QR , United Kingdom
| | - Andrew E Ashley
- Department of Chemistry , Imperial College London , Exhibition Road , South Kensington, London SW7 2AZ , United Kingdom
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