1
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DiMucci IM, Titus CJ, Nordlund D, Bour JR, Chong E, Grigas DP, Hu CH, Kosobokov MD, Martin CD, Mirica LM, Nebra N, Vicic DA, Yorks LL, Yruegas S, MacMillan SN, Shearer J, Lancaster KM. Scrutinizing formally Ni IV centers through the lenses of core spectroscopy, molecular orbital theory, and valence bond theory. Chem Sci 2023; 14:6915-6929. [PMID: 37389249 PMCID: PMC10306094 DOI: 10.1039/d3sc02001k] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 05/30/2023] [Indexed: 07/01/2023] Open
Abstract
Nickel K- and L2,3-edge X-ray absorption spectra (XAS) are discussed for 16 complexes and complex ions with nickel centers spanning a range of formal oxidation states from II to IV. K-edge XAS alone is shown to be an ambiguous metric of physical oxidation state for these Ni complexes. Meanwhile, L2,3-edge XAS reveals that the physical d-counts of the formally NiIV compounds measured lie well above the d6 count implied by the oxidation state formalism. The generality of this phenomenon is explored computationally by scrutinizing 8 additional complexes. The extreme case of NiF62- is considered using high-level molecular orbital approaches as well as advanced valence bond methods. The emergent electronic structure picture reveals that even highly electronegative F-donors are incapable of supporting a physical d6 NiIV center. The reactivity of NiIV complexes is then discussed, highlighting the dominant role of the ligands in this chemistry over that of the metal centers.
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Affiliation(s)
- Ida M DiMucci
- Department of Chemistry and Chemical Biology, Cornell University, Baker Laboratory 162 Sciences Drive Ithaca NY 14853 USA
| | - Charles J Titus
- Department of Physics, Stanford University Stanford California 94305 USA
| | - Dennis Nordlund
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory Menlo Park California 94025 USA
| | - James R Bour
- Department of Chemistry, University of Michigan Ann Arbor Michigan 48109 USA
| | - Eugene Chong
- Department of Chemistry, University of Michigan Ann Arbor Michigan 48109 USA
| | - Dylan P Grigas
- Department of Chemistry and Chemical Biology, Cornell University, Baker Laboratory 162 Sciences Drive Ithaca NY 14853 USA
| | - Chi-Herng Hu
- Department of Chemistry, University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA
| | | | - Caleb D Martin
- Department of Chemistry and Biochemistry, Baylor University Waco Texas 76798 USA
| | - Liviu M Mirica
- Department of Chemistry, University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA
| | - Noel Nebra
- Laboratoire Hétérochimie Fondamentale et Appliquée (LHFA), Université Paul Sabatier, CNRS 118 Route de Narbonne 31062 Toulouse France
| | - David A Vicic
- Department of Chemistry, Lehigh University Bethlehem Pennsylvania 18015 USA
| | - Lydia L Yorks
- Department of Chemistry, Lehigh University Bethlehem Pennsylvania 18015 USA
| | - Sam Yruegas
- Department of Chemistry and Biochemistry, Baylor University Waco Texas 76798 USA
| | - Samantha N MacMillan
- Department of Chemistry and Chemical Biology, Cornell University, Baker Laboratory 162 Sciences Drive Ithaca NY 14853 USA
| | - Jason Shearer
- Department of Chemistry, Trinity University San Antonio Texas 78212-7200 USA
| | - Kyle M Lancaster
- Department of Chemistry and Chemical Biology, Cornell University, Baker Laboratory 162 Sciences Drive Ithaca NY 14853 USA
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2
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Bashir M, Dar AA, Yousuf I. Syntheses, Structural Characterization, and Cytotoxicity Assessment of Novel Mn(II) and Zn(II) Complexes of Aroyl-Hydrazone Schiff Base Ligand. ACS OMEGA 2023; 8:3026-3042. [PMID: 36713712 PMCID: PMC9878661 DOI: 10.1021/acsomega.2c05927] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 12/30/2022] [Indexed: 06/15/2023]
Abstract
This work describes the syntheses, structural characterization, and biological profile of Mn(II)- and Zn(II)-based complexes 1 and 2 derived from the aroyl-hydrazone Schiff base ligand (L1). The synthesized compounds were thoroughly characterized by elemental analysis, Fourier transform infrared spectroscopy (FTIR), UV-vis, electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), and single-crystal X-ray diffraction (s-XRD). Density functional theory (DFT) studies of complexes 1 and 2 were performed to ascertain the structural and electronic properties. Hirshfeld surface analysis was used to investigate different intermolecular interactions that define the stability of crystal lattice structures. To ascertain the therapeutic potential of complexes 1 and 2, in vitro interaction studies were carried out with ct-DNA and bovine serum albumin (BSA) using analytical and multispectroscopic techniques, and the results showed more avid binding of complex 2 than complex 1 and L1. The antioxidant potential of complexes 1 and 2 was examined against the 2,2-diphenyl picrylhydrazyl (DPPH) free radical, which revealed better antioxidant ability of the Mn(II) complex. Moreover, the antibacterial activity of synthesized complexes 1 and 2 was tested against Gram-positive and Gram-negative bacteria in which complex 2 demonstrated more effective bactericidal activity than L1 and complex 1 toward Gram-positive bacteria. Furthermore, the in vitro cytotoxicity assessment of L1 and complexes 1 and 2 was carried out against MDA-MB-231 (triple negative breast cancer) and A549 (lung) cancer cell lines. The cytotoxic results revealed that the polymeric Zn(II) complex exhibited better and selective cytotoxicity against the A549 cancer cell line as was evidenced by its low IC50 value.
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Affiliation(s)
- Masrat Bashir
- Department
of Chemistry, Aligarh Muslim University, Aligarh202002, Uttar Pradesh, India
| | - Aijaz A. Dar
- Department
of Chemistry, University of Kashmir, Hazratbal, Srinagar190006, Jammu & Kashmir, India
| | - Imtiyaz Yousuf
- Department
of Chemistry, Aligarh Muslim University, Aligarh202002, Uttar Pradesh, India
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3
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Shi H, Liang R, Phillips DL, Lee HK, Man WL, Lau KC, Yiu SM, Lau TC. Structure and Reactivity of One- and Two-Electron Oxidized Manganese(V) Nitrido Complexes Bearing a Bulky Corrole Ligand. J Am Chem Soc 2022; 144:7588-7593. [PMID: 35442033 DOI: 10.1021/jacs.2c02506] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
As a strategy to design stable but highly reactive metal nitrido species, we have synthesized a manganese(V) nitrido complex bearing a bulky corrole ligand, [MnV(N)(TTPPC)]- (1, TTPPC is the trianion of 5,10,15-Tris(2,4,6-triphenylphenyl)corrole). Complex 1 is readily oxidized by 1 equiv of Cp2Fe+ to give the neutral complex 2, which can be further oxidized by 1 equiv of [(p-Br-C6H4)3N•+][B(C6F5)4] to afford the cationic complex 3. All three complexes are stable in the solid state and in CH2Cl2 solution, and their molecular structures have been determined by X-ray crystallography. Spectroscopic and theoretical studies indicate that complexes 2 and 3 are best formulated as Mn(V) nitrido π-cation corrole [MnV(N)(TTPPC+•)] and Mn(V) nitrido π-dication corrole [MnV(N)(TTPPC2+)]+, respectively. Complex 3 is the most reactive N atom transfer reagent among isolated nitrido complexes; it reacts with PPh3 and styrene with second-order rate constants of 2.12 × 105 and 1.95 × 10-2 M-1 s-1, respectively, which are >107 faster than that of 2.
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Affiliation(s)
- Huatian Shi
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong999077, People's Republic of China
| | - Runhui Liang
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Pokfulam, Hong Kong999077, People's Republic of China
| | - David Lee Phillips
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Pokfulam, Hong Kong999077, People's Republic of China
| | - Hung Kay Lee
- Department of Chemistry, The Chinese University of Hong Kong, Central Avenue, Shatin, New Territories, Hong Kong999077, People's Republic of China
| | - Wai-Lun Man
- Department of Chemistry, Hong Kong Baptist University, Waterloo Road, Kowloon Tong, Hong Kong999077, People's Republic of China
| | - Kai-Chung Lau
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong999077, People's Republic of China
| | - Shek-Man Yiu
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong999077, People's Republic of China
| | - Tai-Chu Lau
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong999077, People's Republic of China
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4
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Activating dinitrogen for chemical looping ammonia Synthesis: Mn nitride layer growth modeling. Chem Eng Sci 2022. [DOI: 10.1016/j.ces.2021.117287] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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5
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Shi H, Lee HK, Pan Y, Lau KC, Yiu SM, Lam WWY, Man WL, Lau TC. Structure and Reactivity of a Manganese(VI) Nitrido Complex Bearing a Tetraamido Macrocyclic Ligand. J Am Chem Soc 2021; 143:15863-15872. [PMID: 34498856 DOI: 10.1021/jacs.1c08072] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Manganese complexes in +6 oxidation state are rare. Although a number of Mn(VI) nitrido complexes have been generated in solution via one-electron oxidation of the corresponding Mn(V) nitrido species, they are too unstable to isolate. Herein we report the isolation and the X-ray structure of a Mn(VI) nitrido complex, [MnVI(N)(TAML)]- (2), which was obtained by one-electron oxidation of [MnV(N)(TAML)]2- (1). 2 undergoes N atom transfer to PPh3 and styrenes to give Ph3P═NH and aziridines, respectively. A Hammett study for various p-substituted styrenes gives a V-shaped plot; this is rationalized by the ability of 2 to function as either an electrophile or a nucleophile. 2 also undergoes hydride transfer reactions with NADH analogues, such as 10-methyl-9,10-dihydroacridine (AcrH2) and 1-benzyl-1,4-dihydronicotinamide (BNAH). A kinetic isotope effect of 7.3 was obtained when kinetic studies were carried out with AcrH2 and AcrD2. The reaction of 2 with NADH analogues results in the formation of [MnV(N)(TAML-H+)]- (3), which was characterized by ESI/MS, IR spectroscopy, and X-ray crystallography. These results indicate that this reaction occurs via an initial "separated CPET" (separated concerted proton-electron transfer) mechanism; that is, there is a concerted transfer of 1 e- + 1 H+ from AcrH2 (or BNAH) to 2, in which the electron is transferred to the MnVI center, while the proton is transferred to a carbonyl oxygen of TAML rather than to the nitrido ligand.
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Affiliation(s)
- Huatian Shi
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - Hung Kay Lee
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Yi Pan
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - Kai-Chung Lau
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - Shek-Man Yiu
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China
| | - William W Y Lam
- Faculty of Science and Technology, Technological and Higher Education Institute of Hong Kong, Tsing Yi Road, Tsing Yi Island, Hong Kong, China
| | - Wai-Lun Man
- Department of Chemistry, Hong Kong Baptist University, Waterloo Road, Kowloon Tong, Hong Kong, China
| | - Tai-Chu Lau
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong, China
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6
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7
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Abstract
The synthesis and characterization of a series of homoleptic iron complexes [Fe(benzNHCOCO)2]2-/1-/0/1+ supported by the tridentate bis-aryloxide benzimidazolin-2-ylidene pincer ligand benzNHCOCO2- (II) is presented. While the reaction of 2 equiv of free ligand II with a ferrous iron precursor leads to the isolation of the coordination polymer [Fe(benzNHCOCOK)2]n (1), treatment of II with ferric iron salts allows for the synthesis and isolation of the mononuclear, octahedral bis-pincer compound K[Fe(benzNHCOCO)2] (2) and its crown-ether derivative [K(18c6)(THF)2][Fe(benzNHCOCO)2] (3). Electrochemical studies of 2 suggested stable products upon further one- and two-electron oxidation. Hence, treatment of 2 with 1 equiv of AgPF6 yields the charge-neutral species [Fe(benzNHCOCO)2] (4). Similarly, the cationic complex [Fe(benzNHCOCO)2]PF6 (5) is obtained by addition of 2 equiv of AgPF6. The characterization of complexes 1, 3, and 4 reveals iron-centered reduction and oxidation processes; thus, preserving the dianionic, closed-shell structure of both coordinated benzNHCOCO pincer chelates, II. This implies a stabilization of a highly Lewis acidic iron(IV) center by four phenolate anions rather than charge distribution across the ligand framework with a lower formal oxidation state at iron. Notably, the overall charge-neutral iron(IV) complex undergoes reductive elimination of the pincer ligand, providing a metal-free compound that can be described as a spirocyclic imidazolone ketal (6). In contrast, the ligand-metal bonds in 5, formally an iron(V) complex, are considerably covalent, rendering the assignment of its oxidation state challenging, if not impossible. All compounds are fully characterized, and the complexes' electronic structures were studied with a variety of spectroscopic and computational methods, including single-crystal X-ray diffraction (SC-XRD), X-band electron paramagnetic resonance (EPR), and zero-field 57Fe Mössbauer spectroscopy, variable-field and variable-temperature superconducting quantum interference device (SQUID) magnetization measurements, and multi-reference ab initio (NEVPT2/CASSCF) as well as density functional theory (DFT) studies. Taken altogether, the electronic structure of 5 is best described as an iron(IV) center antiferromagnetically coupled to a ligand-centered radical.
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Affiliation(s)
- Lisa Gravogl
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen-Nürnberg, Egerlandstraße 1, 91058 Erlangen, Germany
| | - Frank W Heinemann
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen-Nürnberg, Egerlandstraße 1, 91058 Erlangen, Germany
| | - Dominik Munz
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen-Nürnberg, Egerlandstraße 1, 91058 Erlangen, Germany
| | - Karsten Meyer
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen-Nürnberg, Egerlandstraße 1, 91058 Erlangen, Germany
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8
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Affiliation(s)
- Anuvab Das
- Department of Chemistry, Texas A&M University, College Station, Texas, USA
| | | | - David C. Powers
- Department of Chemistry, Texas A&M University, College Station, Texas, USA
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9
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DeJesus JF, Jenkins DM. A Chiral Macrocyclic Tetra-N-Heterocyclic Carbene Yields an "All Carbene" Iron Alkylidene Complex. Chemistry 2020; 26:1429-1435. [PMID: 31788868 PMCID: PMC7024548 DOI: 10.1002/chem.201905360] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Indexed: 01/12/2023]
Abstract
The first chiral macrocyclic tetra-N-heterocyclic carbene (NHC) ligand has been synthesized. The macrocycle, prepared in high yield and large scale, was ligated onto palladium and iron to give divalent C2 -symmetric square planar complexes. Multinuclear NMR and single crystal X-ray diffraction demonstrated that there are two distinct NHCs on each ligand, due to the bridging chiral cyclohexane. Oxidation of the iron(II) complex with trimethylamine N-oxide yielded a bridging oxo complex. Diazodiphenylmethane reacted with the iron(II) complex at room temperature to give a paramagnetic diazoalkane complex; the same reaction yielded the "all carbene" complex at elevated temperature. Electrochemical measurements support the assignment of the "all carbene" complex being an alkylidene. Notably, the diazoalkane complex can be directly transformed into the alkylidene complex, which had not been previously demonstrated on iron. Finally, a test catalytic reaction with a diazoalkane on the iron(II) complex does not yield the expected cyclopropane, but actually the azine compound.
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Affiliation(s)
- Joseph F DeJesus
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee, 37996, USA
| | - David M Jenkins
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee, 37996, USA
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10
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Terminal uranium(V)-nitride hydrogenations involving direct addition or Frustrated Lewis Pair mechanisms. Nat Commun 2020; 11:337. [PMID: 31953390 PMCID: PMC6969212 DOI: 10.1038/s41467-019-14221-y] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 12/09/2019] [Indexed: 12/03/2022] Open
Abstract
Despite their importance as mechanistic models for heterogeneous Haber Bosch ammonia synthesis from dinitrogen and dihydrogen, homogeneous molecular terminal metal-nitrides are notoriously unreactive towards dihydrogen, and only a few electron-rich, low-coordinate variants demonstrate any hydrogenolysis chemistry. Here, we report hydrogenolysis of a terminal uranium(V)-nitride under mild conditions even though it is electron-poor and not low-coordinate. Two divergent hydrogenolysis mechanisms are found; direct 1,2-dihydrogen addition across the uranium(V)-nitride then H-atom 1,1-migratory insertion to give a uranium(III)-amide, or with trimesitylborane a Frustrated Lewis Pair (FLP) route that produces a uranium(IV)-amide with sacrificial trimesitylborane radical anion. An isostructural uranium(VI)-nitride is inert to hydrogenolysis, suggesting the 5f1 electron of the uranium(V)-nitride is not purely non-bonding. Further FLP reactivity between the uranium(IV)-amide, dihydrogen, and triphenylborane is suggested by the formation of ammonia-triphenylborane. A reactivity cycle for ammonia synthesis is demonstrated, and this work establishes a unique marriage of actinide and FLP chemistries. Despite their importance as mechanistic models for Haber Bosch ammonia synthesis from N2 and H2, high oxidation state terminal metal-nitrides are notoriously unreactive towards H2. Here, the authors report hydrogenolysis of a uranium(V)-nitride, which can occur directly or by Frustrated Lewis Pair chemistry with a borane ancillary.
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11
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Mathe Z, Pantazis DA, Lee HB, Gnewkow R, Van Kuiken BE, Agapie T, DeBeer S. Calcium Valence-to-Core X-ray Emission Spectroscopy: A Sensitive Probe of Oxo Protonation in Structural Models of the Oxygen-Evolving Complex. Inorg Chem 2019; 58:16292-16301. [PMID: 31743026 PMCID: PMC6891804 DOI: 10.1021/acs.inorgchem.9b02866] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Indexed: 12/12/2022]
Abstract
Calcium is an abundant, nontoxic metal that finds many roles in synthetic and biological systems including the oxygen-evolving complex (OEC) of photosystem II. Characterization methods for calcium centers, however, are underdeveloped compared to those available for transition metals. Valence-to-core X-ray emission spectroscopy (VtC XES) selectively probes the electronic structure of an element's chemical environment, providing insight that complements the geometric information available from other techniques. Here, the utility of calcium VtC XES is established using an in-house dispersive spectrometer in combination with density functional theory. Spectral trends are rationalized within a molecular orbital framework, and Kβ2,5 transitions, derived from molecular orbitals with primarily ligand p character, are found to be a promising probe of the calcium coordination environment. In particular, it is shown that calcium VtC XES is sensitive to the electronic structure changes that accompany oxo protonation in Mn3CaO4-based molecular mimics of the OEC. Through correlation to calculations, the potential of calcium VtC XES to address unresolved questions regarding the mechanism of biological water oxidation is highlighted.
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Affiliation(s)
- Zachary Mathe
- Max Planck Institute
for Chemical Energy Conversion, Stiftstrasse 34−36, D-45470 Mülheim an der Ruhr, Germany
| | - Dimitrios A. Pantazis
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der
Ruhr, Germany
| | - Heui Beom Lee
- Division of Chemistry and
Chemical Engineering, California Institute
of Technology, Pasadena, California 91125, United States
| | - Richard Gnewkow
- Institute of Optics and Atomic Physics, Technical University of Berlin, Hardenbergstraße 36, D-10587 Berlin, Germany
| | - Benjamin E. Van Kuiken
- Max Planck Institute
for Chemical Energy Conversion, Stiftstrasse 34−36, D-45470 Mülheim an der Ruhr, Germany
| | - Theodor Agapie
- Division of Chemistry and
Chemical Engineering, California Institute
of Technology, Pasadena, California 91125, United States
| | - Serena DeBeer
- Max Planck Institute
for Chemical Energy Conversion, Stiftstrasse 34−36, D-45470 Mülheim an der Ruhr, Germany
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12
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Citek C, Oyala PH, Peters JC. Mononuclear Fe(I) and Fe(II) Acetylene Adducts and Their Reductive Protonation to Terminal Fe(IV) and Fe(V) Carbynes. J Am Chem Soc 2019; 141:15211-15221. [PMID: 31430146 PMCID: PMC6800224 DOI: 10.1021/jacs.9b06987] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The activity of nitrogenase enzymes, which catalyze the conversion of atmospheric dinitrogen to bioavailable ammonia, is most commonly assayed by the reduction of acetylene gas to ethylene. Despite the practical importance of acetylene as a substrate, little is known concerning its binding or activation in the iron-rich active site. "Fischer-Tropsch" type coupling of non-native C1 substrates to higher-order C≥2 products is also known for nitrogenase, though potential metal-carbon multiply bonded intermediates remain underexplored. Here we report the activation of acetylene gas at a mononuclear tris(phosphino)silyl-iron center, (SiP3)Fe, to give Fe(I) and Fe(II) side-on adducts, including S = 1/2 FeI(η2-HCCH); the latter is characterized by pulse EPR spectroscopy and DFT calculations. Reductive protonation reactions with these compounds converge at stable examples of unusual, formally iron(IV) and iron(V) carbyne complexes, as in diamagnetic (SiP3)Fe≡CCH3 and the paramagnetic cation S = 1/2 [(SiP3)Fe≡CCH3]+. Both alkylcarbyne compounds possess short Fe-C triple bonds (approximately 1.7 Å) trans to the anchoring silane. Pulse EPR experiments, X-band ENDOR and HYSCORE, reveal delocalization of the iron-based spin onto the α-carbyne nucleus in carbon p-orbitals. Furthermore, isotropic coupling of the distal β-CH3 protons with iron indicates hyperconjugation with the spin/hole character on the Fe≡CCH3 unit. The electronic structures of (SiP3)Fe≡CCH3 and [(SiP3)Fe≡CCH3]+ are discussed in comparison to previously characterized, but heterosubstituted, iron carbynes, as well as a hypothetical nitride species, (SiP3)Fe≡N. Such comparisons are germane to the consideration of formally high-valent, multiply bonded Fe≡C and/or Fe≡N intermediates in synthetic or biological catalysis by iron.
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Affiliation(s)
- Cooper Citek
- 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
| | - Jonas C. Peters
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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13
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Hunt C, Peterson M, Anderson C, Chang T, Wu G, Scheiner S, Ménard G. Switchable Aromaticity in an Isostructural Mn Phthalocyanine Series Isolated in Five Separate Redox States. J Am Chem Soc 2019; 141:2604-2613. [DOI: 10.1021/jacs.8b12899] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Camden Hunt
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Madeline Peterson
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Cassidy Anderson
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Tieyan Chang
- ChemMatCARS, University of Chicago, Argonne, Illinois 60493, United States
| | - Guang Wu
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
| | - Steve Scheiner
- Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, United States
| | - Gabriel Ménard
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States
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14
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Cook BJ, Johnson SI, Chambers GM, Kaminsky W, Bullock RM. Triple hydrogen atom abstraction from Mn–NH3 complexes results in cyclophosphazenium cations. Chem Commun (Camb) 2019; 55:14058-14061. [DOI: 10.1039/c9cc06915a] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
All three H atoms of the NH3 ligand of [Mn(depe)2(CO)(NH3)]+ are abstracted by an organic radical, giving a rare cyclophosphazenium cation; computations suggest that insertion of NHx into a Mn–P bond provides a strong thermodynamic driving force.
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Affiliation(s)
- Brian J. Cook
- Center for Molecular Electrocatalysis
- Pacific Northwest National Laboratory P.O. Box 999
- Richland
- USA
| | - Samantha I. Johnson
- Center for Molecular Electrocatalysis
- Pacific Northwest National Laboratory P.O. Box 999
- Richland
- USA
| | - Geoffrey M. Chambers
- Center for Molecular Electrocatalysis
- Pacific Northwest National Laboratory P.O. Box 999
- Richland
- USA
| | | | - R. Morris Bullock
- Center for Molecular Electrocatalysis
- Pacific Northwest National Laboratory P.O. Box 999
- Richland
- USA
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15
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Martinie RJ, Blaesi EJ, Bollinger JM, Krebs C, Finkelstein KD, Pollock CJ. Two-Color Valence-to-Core X-ray Emission Spectroscopy Tracks Cofactor Protonation State in a Class I Ribonucleotide Reductase. Angew Chem Int Ed Engl 2018; 57:12754-12758. [PMID: 30075052 PMCID: PMC6579043 DOI: 10.1002/anie.201807366] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 07/20/2018] [Indexed: 12/20/2022]
Abstract
Proton transfer reactions are of central importance to a wide variety of biochemical processes, though determining proton location and monitoring proton transfers in biological systems is often extremely challenging. Herein, we use two-color valence-to-core X-ray emission spectroscopy (VtC XES) to identify protonation events across three oxidation states of the O2 -activating, radical-initiating manganese-iron heterodinuclear cofactor in a class I-c ribonucleotide reductase. This is the first application of VtC XES to an enzyme intermediate and the first simultaneous measurement of two-color VtC spectra. In contrast to more conventional methods of assessing protonation state, VtC XES is a more direct probe applicable to a wide range of metalloenzyme systems. These data, coupled to insight provided by DFT calculations, allow the inorganic cores of the MnIV FeIV and MnIV FeIII states of the enzyme to be assigned as MnIV (μ-O)2 FeIV and MnIV (μ-O)(μ-OH)FeIII , respectively.
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Affiliation(s)
- Ryan J Martinie
- Department of Chemistry, The Pennsylvania State University, 318 Chemistry Building, University Park, PA, 16802, USA
| | - Elizabeth J Blaesi
- Department of Chemistry, The Pennsylvania State University, 318 Chemistry Building, University Park, PA, 16802, USA
| | - J Martin Bollinger
- Department of Chemistry and Department of Biochemistry and Molecular Biology, The Pennsylvania State University, 318 Chemistry Building, University Park, PA, 16802, USA
| | - Carsten Krebs
- Department of Chemistry and Department of Biochemistry and Molecular Biology, The Pennsylvania State University, 318 Chemistry Building, University Park, PA, 16802, USA
| | - Kenneth D Finkelstein
- Cornell High Energy Synchrotron Source, Wilson Laboratory, Cornell University, Ithaca, NY, 14853, USA
| | - Christopher J Pollock
- Department of Chemistry, The Pennsylvania State University, 318 Chemistry Building, University Park, PA, 16802, USA
- Present address: Cornell High Energy Synchrotron Source, Wilson Laboratory, Cornell University, Ithaca, NY, 14853, USA
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16
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Martinie RJ, Blaesi EJ, Bollinger JM, Krebs C, Finkelstein KD, Pollock CJ. Two‐Color Valence‐to‐Core X‐ray Emission Spectroscopy Tracks Cofactor Protonation State in a Class I Ribonucleotide Reductase. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201807366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Ryan J. Martinie
- Department of Chemistry The Pennsylvania State University 318 Chemistry Building University Park PA 16802 USA
| | - Elizabeth J. Blaesi
- Department of Chemistry The Pennsylvania State University 318 Chemistry Building University Park PA 16802 USA
| | - J. Martin Bollinger
- Department of Chemistry and Department of Biochemistry and Molecular Biology The Pennsylvania State University 318 Chemistry Building University Park PA 16802 USA
| | - Carsten Krebs
- Department of Chemistry and Department of Biochemistry and Molecular Biology The Pennsylvania State University 318 Chemistry Building University Park PA 16802 USA
| | - Kenneth D. Finkelstein
- Cornell High Energy Synchrotron Source, Wilson Laboratory Cornell University Ithaca NY 14853 USA
| | - Christopher J. Pollock
- Department of Chemistry The Pennsylvania State University 318 Chemistry Building University Park PA 16802 USA
- Present address: Cornell High Energy Synchrotron Source Wilson Laboratory Cornell University Ithaca NY 14853 USA
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17
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Buss JA, Cheng C, Agapie T. A Low‐Valent Molybdenum Nitride Complex: Reduction Promotes Carbonylation Chemistry. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201803728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Joshua A. Buss
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
| | - Christine Cheng
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
| | - Theodor Agapie
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
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18
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Cheng J, Wang L, Wang P, Deng L. High-Oxidation-State 3d Metal (Ti-Cu) Complexes with N-Heterocyclic Carbene Ligation. Chem Rev 2018; 118:9930-9987. [PMID: 30011189 DOI: 10.1021/acs.chemrev.8b00096] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
High-oxidation-state 3d metal species have found a wide range of applications in modern synthetic chemistry and materials science. They are also implicated as key reactive species in biological reactions. These applications have thus prompted explorations of their formation, structure, and properties. While the traditional wisdom regarding these species was gained mainly from complexes supported by nitrogen- and oxygen-donor ligands, recent studies with N-heterocyclic carbenes (NHCs), which are widely used for the preparation of low-oxidation-state transition metal complexes in organometallic chemistry, have led to the preparation of a large variety of isolable high-oxidation-state 3d metal complexes with NHC ligation. Since the first report in this area in the 1990s, isolable complexes of this type have been reported for titanium(IV), vanadium(IV,V), chromium(IV,V), manganese(IV,V), iron(III,IV,V), cobalt(III,IV,V), nickel(IV), and copper(II). With the aim of providing an overview of this intriguing field, this Review summarizes our current understanding of the synthetic methods, structure and spectroscopic features, reactivity, and catalytic applications of high-oxidation-state 3d metal NHC complexes of titanium to copper. In addition to this progress, factors affecting the stability and reactivity of high-oxidation-state 3d metal NHC species are also presented, as well as perspectives on future efforts.
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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
| | - Lijun Wang
- 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
| | - Peng Wang
- 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
| | - 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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19
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Buss JA, Cheng C, Agapie T. A Low‐Valent Molybdenum Nitride Complex: Reduction Promotes Carbonylation Chemistry. Angew Chem Int Ed Engl 2018; 57:9670-9674. [DOI: 10.1002/anie.201803728] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 05/31/2018] [Indexed: 11/07/2022]
Affiliation(s)
- Joshua A. Buss
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
| | - Christine Cheng
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
| | - Theodor Agapie
- Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA 91125 USA
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20
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Suntrup L, Kleoff M, Sarkar B. Serendipitous discoveries of new coordination modes of the 1,5-regioisomer of 1,2,3-triazoles enroute to the attempted synthesis of a carbon-anchored tri-mesoionic carbene. Dalton Trans 2018; 47:7992-8002. [DOI: 10.1039/c8dt01521j] [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
Di-, tri-, and tetra-nuclear Ag(i) complexes, a protonated ligand and a hydroxyl–alkyl-substituted triazolium salt with the 1,5-substituted-1,2,3-triazole ligand are presented.
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Affiliation(s)
- Lisa Suntrup
- Freie Universität Berlin
- Institut für Chemie und Biochemie
- 14195 Berlin
- Germany
| | - Merlin Kleoff
- Freie Universität Berlin
- Institut für Chemie und Biochemie
- 14195 Berlin
- Germany
| | - Biprajit Sarkar
- Freie Universität Berlin
- Institut für Chemie und Biochemie
- 14195 Berlin
- Germany
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21
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Charra V, de Frémont P, Braunstein P. Multidentate N-heterocyclic carbene complexes of the 3d metals: Synthesis, structure, reactivity and catalysis. Coord Chem Rev 2017. [DOI: 10.1016/j.ccr.2017.03.007] [Citation(s) in RCA: 113] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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22
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Amabilino S, Deeth RJ. DFT Analysis of Spin Crossover in Mn(III) Complexes: Is a Two-Electron S = 2 to S = 0 Spin Transition Feasible? Inorg Chem 2017; 56:2602-2613. [DOI: 10.1021/acs.inorgchem.6b02793] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Silvia Amabilino
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Robert J. Deeth
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
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23
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Clarke RM, Storr T. Tuning Electronic Structure To Control Manganese Nitride Activation. J Am Chem Soc 2016; 138:15299-15302. [DOI: 10.1021/jacs.6b09576] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ryan M. Clarke
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S4
| | - Tim Storr
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S4
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24
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Effect of Protonated Amine Molecules on the Oxygen Reduction Reaction on Metal-Nitrogen-Carbon-Based Catalysts. Electrocatalysis (N Y) 2016. [DOI: 10.1007/s12678-016-0341-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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25
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Baglia RA, Krest CM, Yang T, Leeladee P, Goldberg DP. High-Valent Manganese-Oxo Valence Tautomers and the Influence of Lewis/Brönsted Acids on C-H Bond Cleavage. Inorg Chem 2016; 55:10800-10809. [PMID: 27689821 DOI: 10.1021/acs.inorgchem.6b02109] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The addition of Lewis or Brönsted acids (LA = Zn(OTf)2, B(C6F5)3, HBArF, TFA) to the high-valent manganese-oxo complex MnV(O)(TBP8Cz) results in the stabilization of a valence tautomer MnIV(O-LA)(TBP8Cz•+). The ZnII and B(C6F5)3 complexes were characterized by manganese K-edge X-ray absorption spectroscopy (XAS). The position of the edge energies and the intensities of the pre-edge (1s to 3d) peaks confirm that the Mn ion is in the +4 oxidation state. Fitting of the extended X-ray absorption fine structure (EXAFS) region reveals 4 N/O ligands at Mn-Nave = 1.89 Å and a fifth N/O ligand at 1.61 Å, corresponding to the terminal oxo ligand. This Mn-O bond length is elongated compared to the MnV(O) starting material (Mn-O = 1.55 Å). The reactivity of MnIV(O-LA)(TBP8Cz•+) toward C-H substrates was examined, and it was found that H• abstraction from C-H bonds occurs in a 1:1 stoichiometry, giving a MnIV complex and the dehydrogenated organic product. The rates of C-H cleavage are accelerated for the MnIV(O-LA)(TBP8Cz•+) valence tautomer as compared to the MnV(O) valence tautomer when LA = ZnII, B(C6F5)3, and HBArF, whereas for LA = TFA, the C-H cleavage rate is slightly slower than when compared to MnV(O). A large, nonclassical kinetic isotope effect of kH/kD = 25-27 was observed for LA = B(C6F5)3 and HBArF, indicating that H-atom transfer (HAT) is the rate-limiting step in the C-H cleavage reaction and implicating a potential tunneling mechanism for HAT. The reactivity of MnIV(O-LA)(TBP8Cz•+) toward C-H bonds depends on the strength of the Lewis acid. The HAT reactivity is compared with the analogous corrole complex MnIV(O-H)(tpfc•+) recently reported (J. Am. Chem. Soc. 2015, 137, 14481-14487).
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Affiliation(s)
- Regina A Baglia
- Department of Chemistry, The Johns Hopkins University , 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Courtney M Krest
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Tzuhsiung Yang
- Department of Chemistry, The Johns Hopkins University , 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Pannee Leeladee
- Department of Chemistry, The Johns Hopkins University , 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - David P Goldberg
- Department of Chemistry, The Johns Hopkins University , 3400 North Charles Street, Baltimore, Maryland 21218, United States
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26
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Ding M, Cutsail III GE, Aravena D, Amoza M, Rouzières M, Dechambenoit P, Losovyj Y, Pink M, Ruiz E, Clérac R, Smith JM. A Low Spin Manganese(IV) Nitride Single Molecule Magnet. Chem Sci 2016; 7:6132-6140. [PMID: 27746891 PMCID: PMC5058364 DOI: 10.1039/c6sc01469k] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Accepted: 06/09/2016] [Indexed: 01/26/2023] Open
Abstract
Structural, spectroscopic and magnetic methods have been used to characterize the tris(carbene)borate compound PhB(MesIm)3Mn≡N as a four-coordinate manganese(IV) complex with a low spin (S = 1/2) configuration. The slow relaxation of the magnetization in this complex, i.e. its single-molecule magnet (SMM) properties, is revealed under an applied dc field. Multireference quantum mechanical calculations indicate that this SMM behavior originates from an anisotropic ground doublet stabilized by spin-orbit coupling. Consistent theoretical and experiment data show that the resulting magnetization dynamics in this system is dominated by ground state quantum tunneling, while its temperature dependence is influenced by Raman relaxation.
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Affiliation(s)
- Mei Ding
- Department of Chemistry
, Indiana University
,
800 E. Kirkwood Ave.
, Bloomington
, IN 47405
, USA
.
| | - George E. Cutsail III
- Department of Chemistry
, Northwestern University
,
2145 Sheridan Road
, Evanston
, IL 60208
, USA
| | - Daniel Aravena
- Departamento de Química de los Materiales
, Facultad de Química y Biología
, Universidad de Santiago de Chile (USACH)
,
Casilla 40, Correo 33
, Santiago
, Chile
| | - Martín Amoza
- Departament de Química Inorgànica
, Institut de Recerca de Química Teòrica i Computacional
, Universitat de Barcelona
,
Diagonal 645
, Barcelona
, 08028 Spain
.
| | - Mathieu Rouzières
- CNRS
, CRPP
, UPR 8641
,
F-33600 Pessac
, France
.
- Univ. Bordeaux
, CRPP
, UPR 8641
,
F-33600 Pessac
, France
| | - Pierre Dechambenoit
- CNRS
, CRPP
, UPR 8641
,
F-33600 Pessac
, France
.
- Univ. Bordeaux
, CRPP
, UPR 8641
,
F-33600 Pessac
, France
| | - Yaroslav Losovyj
- Department of Chemistry
, Indiana University
,
800 E. Kirkwood Ave.
, Bloomington
, IN 47405
, USA
.
| | - Maren Pink
- Department of Chemistry
, Indiana University
,
800 E. Kirkwood Ave.
, Bloomington
, IN 47405
, USA
.
| | - Eliseo Ruiz
- Departament de Química Inorgànica
, Institut de Recerca de Química Teòrica i Computacional
, Universitat de Barcelona
,
Diagonal 645
, Barcelona
, 08028 Spain
.
| | - Rodolphe Clérac
- CNRS
, CRPP
, UPR 8641
,
F-33600 Pessac
, France
.
- Univ. Bordeaux
, CRPP
, UPR 8641
,
F-33600 Pessac
, France
| | - Jeremy M. Smith
- Department of Chemistry
, Indiana University
,
800 E. Kirkwood Ave.
, Bloomington
, IN 47405
, USA
.
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27
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A Practical Guide to High-resolution X-ray Spectroscopic Measurements and their Applications in Bioinorganic Chemistry. Isr J Chem 2016. [DOI: 10.1002/ijch.201600037] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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28
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Walroth RC, Uebler JWH, Lancaster KM. Probing Cu(I) in homogeneous catalysis using high-energy-resolution fluorescence-detected X-ray absorption spectroscopy. Chem Commun (Camb) 2016; 51:9864-7. [PMID: 25994112 DOI: 10.1039/c5cc01827g] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Metal-to-ligand charge transfer excitations in Cu(I) X-ray absorption spectra are introduced as spectroscopic handles for the characterization of species in homogeneous catalytic reaction mixtures. Analysis is supported by correlation of a spectral library to calculations and to complementary spectroscopic parameters.
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Affiliation(s)
- Richard C Walroth
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
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29
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Walroth RC, Lukens JT, MacMillan SN, Finkelstein KD, Lancaster KM. Spectroscopic Evidence for a 3d10 Ground State Electronic Configuration and Ligand Field Inversion in [Cu(CF3)4]1–. J Am Chem Soc 2016; 138:1922-31. [DOI: 10.1021/jacs.5b10819] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Richard C. Walroth
- Department
of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - James T. Lukens
- Department
of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Samantha N. MacMillan
- Department
of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Kenneth D. Finkelstein
- Cornell
High Energy Synchrotron Source, Wilson Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Kyle M. Lancaster
- Department
of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
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30
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Reilly SW, Webster CE, Hollis TK, Valle HU. Transmetallation from CCC-NHC pincer Zr complexes in the synthesis of air-stable CCC-NHC pincer Co(iii) complexes and initial hydroboration trials. Dalton Trans 2016; 45:2823-8. [PMID: 26814468 DOI: 10.1039/c5dt04752h] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Development of CCC-NHC pincer Co complexes via transmetalation from Zr is reported. Formation of these air-stable Co(iii) complexes was achieved through use of a CoCl2 or Co(acac)3in situ or with a discrete CCC-NHC pincer Zr transmetallating agent. Preliminary activity in the hydroboration of styrene is reported. This facile methodology will further the development of CCC-NHC pincer first-row transition metal complexes.
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Affiliation(s)
- Sean W Reilly
- Department of Chemistry, Mississippi State University, Mississippi State, MS 39762-9573, USA.
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31
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Pollock CJ, DeBeer S. Insights into the geometric and electronic structure of transition metal centers from valence-to-core X-ray emission spectroscopy. Acc Chem Res 2015; 48:2967-75. [PMID: 26401686 DOI: 10.1021/acs.accounts.5b00309] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A long-standing goal of inorganic chemists is the ability to decipher the geometric and electronic structures of chemical species. This is particularly true for the study of small molecule and biological catalysts, where this knowledge is critical for understanding how these molecules effect chemical transformations. Numerous techniques are available for this task, and collectively they have enabled detailed understanding of many complex chemical systems. Despite this battery of probes, however, challenges still remain, particularly when the structural question involves subtle perturbations of the ligands bound to a metal center, as is often the case during chemical reactions. It is here that, as an emerging probe of chemical structure, valence-to-core (VtC) X-ray emission spectroscopy (XES) holds promise. VtC XES begins with ionization of a 1s electron from a metal ion by high energy X-ray photons. Electrons residing in ligand-localized valence orbitals decay to fill the 1s hole, emitting fluorescent photons in the process; in this manner, VtC XES primarily probes the filled, ligand-based orbitals of a metal complex. This is in contrast to other X-ray based techniques, such as K-edge X-ray absorption and EXAFS, which probe the unoccupied d-manifold orbitals and atomic scatterers surrounding the metal, respectively. As a hard X-ray technique, VtC XES experiments can be performed on a variety of sample states and environments, enabling application to demanding systems, such as high pressure cells and dilute biological samples. VtC XES thus can offer unique insights into the geometric and electronic structures of inorganic complexes. In recent years, we have sought to use VtC XES in the study of inorganic and bioinorganic complexes; doing so, however, first required a thorough and detailed understanding of the information content of these spectra. Extensive experimental surveys of model compounds coupled to the insights provided by DFT calculated spectra of real and hypothetical compounds allowed the development of a framework whereby VtC XES spectra may be understood in terms of a molecular orbital picture. Specifically, VtC spectra may be interpreted as a probe of electronic structure for the ligands bound to a metal center, enabling access to chemical information that can be difficult to obtain with other methods. Examples of this include the ability to (1) assess the identity and number of atomic/small molecule ligands bound to a metal center, (2) quantify the degree of bond activation of a small molecule substrate, and (3) establish the protonation state of donor atoms. With this foundation established, VtC has been meaningfully applied to long-standing questions in bioinorganic chemistry, with the potential for numerous future applications in all areas of metal-mediated catalysis.
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Affiliation(s)
- Christopher J. Pollock
- Department
of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Serena DeBeer
- Max-Planck-Institute
for Chemical Energy Conversion, Stiftstrasse
34-36, D-45470 Mülheim
an der Ruhr, Germany
- Department
of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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32
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Al-Afyouni MH, Krishnan VM, Arman HD, Tonzetich ZJ. Synthesis and Reactivity of Manganese(II) Complexes Containing N-Heterocyclic Carbene Ligands. Organometallics 2015. [DOI: 10.1021/acs.organomet.5b00684] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Malik H. Al-Afyouni
- Department
of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
- Department
of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - V. Mahesh Krishnan
- Department
of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Hadi D. Arman
- Department
of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Zachary J. Tonzetich
- Department
of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, United States
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33
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Das B, Behm M, Lindbergh G, Reddy M, Chowdari B. High performance metal nitrides, MN (M = Cr, Co) nanoparticles for non-aqueous hybrid supercapacitors. ADV POWDER TECHNOL 2015. [DOI: 10.1016/j.apt.2015.02.001] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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34
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Kropp H, Scheurer A, Heinemann FW, Bendix J, Meyer K. Coordination-Induced Spin-State Change in Manganese(V) Complexes: The Electronic Structure of Manganese(V) Nitrides. Inorg Chem 2015; 54:3562-72. [DOI: 10.1021/acs.inorgchem.5b00112] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Henning Kropp
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Egerlandstrasse
1, 91058 Erlangen, Germany
| | - Andreas Scheurer
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Egerlandstrasse
1, 91058 Erlangen, Germany
| | - Frank W. Heinemann
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Egerlandstrasse
1, 91058 Erlangen, Germany
| | - Jesper Bendix
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
| | - Karsten Meyer
- Department of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Egerlandstrasse
1, 91058 Erlangen, Germany
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35
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Gul S, Ng JWD, Alonso-Mori R, Kern J, Sokaras D, Anzenberg E, Lassalle-Kaiser B, Gorlin Y, Weng TC, Zwart PH, Zhang JZ, Bergmann U, Yachandra VK, Jaramillo TF, Yano J. Simultaneous detection of electronic structure changes from two elements of a bifunctional catalyst using wavelength-dispersive X-ray emission spectroscopy and in situ electrochemistry. Phys Chem Chem Phys 2015; 17:8901-12. [PMID: 25747045 DOI: 10.1039/c5cp01023c] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Multielectron catalytic reactions, such as water oxidation, nitrogen reduction, or hydrogen production in enzymes and inorganic catalysts often involve multimetallic clusters. In these systems, the reaction takes place between metals or metals and ligands to facilitate charge transfer, bond formation/breaking, substrate binding, and release of products. In this study, we present a method to detect X-ray emission signals from multiple elements simultaneously, which allows for the study of charge transfer and the sequential chemistry occurring between elements. Kβ X-ray emission spectroscopy (XES) probes charge and spin states of metals as well as their ligand environment. A wavelength-dispersive spectrometer based on the von Hamos geometry was used to disperse Kβ signals of multiple elements onto a position detector, enabling an XES spectrum to be measured in a single-shot mode. This overcomes the scanning needs of the scanning spectrometers, providing data free from temporal and normalization errors and therefore ideal to follow sequential chemistry at multiple sites. We have applied this method to study MnOx-based bifunctional electrocatalysts for the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR). In particular, we investigated the effects of adding a secondary element, Ni, to form MnNiOx and its impact on the chemical states and catalytic activity, by tracking the redox characteristics of each element upon sweeping the electrode potential. The detection scheme we describe here is general and can be applied to time-resolved studies of materials consisting of multiple elements, to follow the dynamics of catalytic and electron transfer reactions.
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Affiliation(s)
- Sheraz Gul
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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MacMillan SN, Walroth R, Perry DM, Morsing TJ, Lancaster KM. Ligand-sensitive but not ligand-diagnostic: evaluating Cr valence-to-core X-ray emission spectroscopy as a probe of inner-sphere coordination. Inorg Chem 2015; 54:205-14. [PMID: 25496512 PMCID: PMC4335811 DOI: 10.1021/ic502152r] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Indexed: 01/10/2023]
Abstract
This paper explores the strengths and limitations of valence-to-core X-ray emission spectroscopy (V2C XES) as a probe of coordination environments. A library was assembled from spectra obtained for 12 diverse Cr complexes and used to calibrate density functional theory (DFT) calculations of V2C XES band energies. A functional dependence study was undertaken to benchmark predictive accuracy. All 7 functionals tested reproduce experimental V2C XES energies with an accuracy of 0.5 eV. Experimentally calibrated, DFT calculated V2C XES spectra of 90 Cr compounds were used to produce a quantitative spectrochemical series showing the V2C XES band energy ranges for ligands comprising 18 distinct classes. Substantial overlaps are detected in these ranges, which complicates the use of V2C XES to identify ligands in the coordination spheres of unknown Cr compounds. The ligand-dependent origins of V2C intensity are explored for a homologous series of [Cr(III)(NH3)5X](2+) (X = F, Cl, Br, and I) to rationalize the variable intensity contributions of these ligand classes.
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Affiliation(s)
- Samantha N. MacMillan
- Department of Chemistry
and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Richard
C. Walroth
- Department of Chemistry
and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Demetra M. Perry
- Department of Chemistry
and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Thorbjørn J. Morsing
- Department of Chemistry
and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Kyle M. Lancaster
- Department of Chemistry
and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
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Zolnhofer EM, Käß M, Khusniyarov MM, Heinemann FW, Maron L, van Gastel M, Bill E, Meyer K. An Intermediate Cobalt(IV) Nitrido Complex and its N-Migratory Insertion Product. J Am Chem Soc 2014; 136:15072-8. [DOI: 10.1021/ja508144j] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Eva M. Zolnhofer
- Department
of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen - Nürnberg (FAU), Egerlandstr. 1, 91058 Erlangen, Germany
| | - Martina Käß
- Department
of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen - Nürnberg (FAU), Egerlandstr. 1, 91058 Erlangen, Germany
| | - Marat M. Khusniyarov
- Department
of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen - Nürnberg (FAU), Egerlandstr. 1, 91058 Erlangen, Germany
| | - Frank W. Heinemann
- Department
of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen - Nürnberg (FAU), Egerlandstr. 1, 91058 Erlangen, Germany
| | - Laurent Maron
- Université de Toulouse et CNRS, NSA, UPS, CNRS, UMR 5215 LPCNO, 135 avenue de Rangueil, 31077 Toulouse, France
| | - Maurice van Gastel
- Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34−36, 45470 Mülheim, Germany
| | - Eckhard Bill
- Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34−36, 45470 Mülheim, Germany
| | - Karsten Meyer
- Department
of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander University Erlangen - Nürnberg (FAU), Egerlandstr. 1, 91058 Erlangen, Germany
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Pollock CJ, Lancaster KM, Finkelstein KD, DeBeer S. Study of iron dimers reveals angular dependence of valence-to-core X-ray emission spectra. Inorg Chem 2014; 53:10378-85. [PMID: 25211540 PMCID: PMC4186667 DOI: 10.1021/ic501462y] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Transition-metal Kβ X-ray emission spectroscopy (XES) is a developing technique that probes the occupied molecular orbitals of a metal complex. As an element-specific probe of metal centers, Kβ XES is finding increasing applications in catalytic and, in particular, bioinorganic systems. For the continued development of XES as a probe of these complex systems, however, the full range of factors which contribute to XES spectral modulations must be explored. In this report, an investigation of a series of oxo-bridged iron dimers reveals that the intensity of valence-to-core features is sensitive to the Fe-O-Fe bond angle. The intensity of these features has a well-known dependence on metal-ligand bond distance, but a dependence upon bond angle has not previously been documented. Herein, we explore the angular dependence of valence-to-core XES features both experimentally and computationally. Taken together, these results show that, as the Fe-O-Fe angle decreases, the intensity of the Kβ″ feature increases and that this effect is modulated by increasing amounts of Fe np mixing into the O 2s orbital at smaller bond angles. The relevance of these findings to the identification of oxygenated intermediates in bioinorganic systems is highlighted, with special emphasis given to the case of soluble methane monooxygenase.
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Affiliation(s)
- Christopher J Pollock
- Max-Planck-Institut für Chemische Energiekonversion , Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
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Bellemin-Laponnaz S, Dagorne S. Group 1 and 2 and early transition metal complexes bearing N-heterocyclic carbene ligands: coordination chemistry, reactivity, and applications. Chem Rev 2014; 114:8747-74. [PMID: 25144918 DOI: 10.1021/cr500227y] [Citation(s) in RCA: 251] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Stéphane Bellemin-Laponnaz
- IPCMS (Institut de Physique et Chimie des Matériaux de Strasbourg), CNRS-Université de Strasbourg , 23 rue du Loess BP 43, F-67034 Strasbourg, France
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Hall ER, Pollock CJ, Bendix J, Collins TJ, Glatzel P, DeBeer S. Valence-to-Core-Detected X-ray Absorption Spectroscopy: Targeting Ligand Selectivity. J Am Chem Soc 2014; 136:10076-84. [DOI: 10.1021/ja504206y] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Eleanor R. Hall
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
- Department
of Chemistry, University of Oxford, Oxford OX1 2JD, United Kingdom
| | - Christopher J. Pollock
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Jesper Bendix
- Department
of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
| | - Terrence J. Collins
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Pieter Glatzel
- European
Synchrotron Radiation Facility, 71 Rue des Martyrs, 38000 Grenoble, France
| | - Serena DeBeer
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
- Department
of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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Käß M, Hohenberger J, Adelhardt M, Zolnhofer EM, Mossin S, Heinemann FW, Sutter J, Meyer K. Synthesis and Characterization of Divalent Manganese, Iron, and Cobalt Complexes in Tripodal Phenolate/N-Heterocyclic Carbene Ligand Environments. Inorg Chem 2013; 53:2460-70. [DOI: 10.1021/ic4024053] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Martina Käß
- Department
of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-University Erlangen-Nuremberg, Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Johannes Hohenberger
- Department
of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-University Erlangen-Nuremberg, Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Mario Adelhardt
- Department
of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-University Erlangen-Nuremberg, Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Eva M. Zolnhofer
- Department
of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-University Erlangen-Nuremberg, Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Susanne Mossin
- Department
of Chemistry, Technical University of Denmark, Kemitorvet 207, 2800 Kgs. Lyngby, Denmark
| | - Frank W. Heinemann
- Department
of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-University Erlangen-Nuremberg, Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Jörg Sutter
- Department
of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-University Erlangen-Nuremberg, Egerlandstrasse 1, 91058 Erlangen, Germany
| | - Karsten Meyer
- Department
of Chemistry and Pharmacy, Inorganic Chemistry, Friedrich-Alexander-University Erlangen-Nuremberg, Egerlandstrasse 1, 91058 Erlangen, Germany
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Delgado-Jaime MU, DeBeer S, Bauer M. Valence-to-core X-ray emission spectroscopy of iron-carbonyl complexes: implications for the examination of catalytic intermediates. Chemistry 2013; 19:15888-97. [PMID: 24222392 DOI: 10.1002/chem.201301913] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Indexed: 11/12/2022]
Abstract
Valence-to-core X-ray emission spectroscopy (V2C XES) has been applied to a series of compounds relevant to both homogeneous catalysts and intermediates in heterogeneous reactions, namely [Fe(CO)5], [Fe2(CO)9], [Fe3(CO)12], [Fe(CO)3(cod)] (cod=cyclo-octadienyl), [Fe2Cp2(CO)4] (Cp=cyclo-pentadienyl), [Fe2Cp*2(CO)4] (Cp*=tetramethylcyclopentadienyl), and [FeCp(CO)2(thf)][B(ArF)4] (ArF=pentafluorophenyl). DFT calculations of the V2C XES spectra show very good agreement with experiment, which allows for an in depth analysis of the origins of the observed spectral signatures. It is demonstrated that the observed spectral features can be broken down into specific ligand and metal fragment contributions. The relative intensities of the observed features are further explained through a quantitative investigation of the metal 3p and 4p contributions to the spectra. The ability to use V2C XES to separate carbonyl, hydrocarbon, and solvent contributions is highlighted.
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Bogart JA, Lewis AJ, Medling SA, Piro NA, Carroll PJ, Booth CH, Schelter EJ. Homoleptic Cerium(III) and Cerium(IV) Nitroxide Complexes: Significant Stabilization of the 4+ Oxidation State. Inorg Chem 2013; 52:11600-7. [DOI: 10.1021/ic401974t] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Justin A. Bogart
- P. Roy and Diana T. Vagelos
Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Andrew J. Lewis
- P. Roy and Diana T. Vagelos
Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Scott A. Medling
- Chemical Sciences
Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Nicholas A. Piro
- P. Roy and Diana T. Vagelos
Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Patrick J. Carroll
- P. Roy and Diana T. Vagelos
Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Corwin H. Booth
- Chemical Sciences
Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Eric J. Schelter
- P. Roy and Diana T. Vagelos
Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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45
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Gloaguen Y, Jongens LM, Reek JNH, Lutz M, de Bruin B, van der Vlugt JI. Reductive Elimination at an Ortho-Metalated Iridium(III) Hydride Bearing a Tripodal Tetraphosphorus Ligand. Organometallics 2013. [DOI: 10.1021/om400451y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Yann Gloaguen
- Homogeneous & Supramolecular Catalysis, van ’t Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Lianne M. Jongens
- Homogeneous & Supramolecular Catalysis, van ’t Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Joost N. H. Reek
- Homogeneous & Supramolecular Catalysis, van ’t Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Martin Lutz
- Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Faculty of Science, Utrecht University, The Netherlands
| | - Bas de Bruin
- Homogeneous & Supramolecular Catalysis, van ’t Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Jarl Ivar van der Vlugt
- Homogeneous & Supramolecular Catalysis, van ’t Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
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46
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Chandrasekaran P, Chiang KP, Nordlund D, Bergmann U, Holland PL, DeBeer S. Sensitivity of X-ray core spectroscopy to changes in metal ligation: a systematic study of low-coordinate, high-spin ferrous complexes. Inorg Chem 2013; 52:6286-98. [PMID: 23662855 DOI: 10.1021/ic3021723] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In order to assess the sensitivity and complementarity of X-ray absorption and emission spectroscopies for determining changes in the metal ligation sphere, a systematic experimental and theoretical study of iron model complexes has been carried out. A series of high-spin ferrous complexes, in which the ligation sphere has been varied from a three-coordinate complex, [L(tBu)Fe(SPh)] (1) (where L(tBu) = bulky β-diketiminate ligand; SPh = phenyl thiolate) to four-coordinate complexes [L(tBu)Fe(SPh)(X)] (where X = CN(t)Bu (2); 1-methylimidazole (3); or N,N-dimethylformamide (DMF) (4)), has been investigated using a combination of Fe K-edge X-ray absorption (XAS) and Kβ X-ray emission (XES) spectroscopies. The Fe K XAS pre-edge and edge of all four complexes are consistent with a high-spin ferrous assignment, with the largest differences in the pre-edge intensities attributed to changes in covalency of the fourth coordination site. The X-ray emission spectra show pronounced changes in the valence to core region (V2C) as the identity of the coordinated ligand is varied. The experimental results have been correlated to density functional theory (DFT) calculations, to understand key molecular orbital contributions to the observed absorption and emission features. The calculations also have been extended to a series of hypothetical high-spin iron complexes to understand the sensitivity of XAS and XES techniques to different ligand protonation states ([L(tBu)Fe(II)(SPh)(NHn)](3-n) (n = 3, 2, 1, 0)), metal oxidation states [L(tBu)Fe(SPh)(N)](n-) (n = 3, 2, 1), and changes in the ligand identity [L(tBu)Fe(IV)(SPh)(X)](n-) (X = C(4-), N(3-), O(2-); n = 2, 1, 0). This study demonstrates that XAS pre-edge data have greater sensitivity to changes in oxidation state, while valence to core (V2C) XES data provide a more sensitive probe of ligand identity and protonation state. The combination of multiple X-ray spectroscopic methods with DFT results thus has the potential to provide for detailed characterization of complex inorganic systems in both chemical and biological catalysis.
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Affiliation(s)
- P Chandrasekaran
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
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Bass HM, Cramer SA, McCullough AS, Bernstein KJ, Murdock CR, Jenkins DM. Employing Dianionic Macrocyclic Tetracarbenes To Synthesize Neutral Divalent Metal Complexes. Organometallics 2013. [DOI: 10.1021/om400043z] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Heather M. Bass
- Department of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996-1600, United
States
| | - S. Alan Cramer
- Department of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996-1600, United
States
| | - Alexander S. McCullough
- Department of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996-1600, United
States
| | - Karl J. Bernstein
- Department of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996-1600, United
States
| | - Christopher R. Murdock
- Department of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996-1600, United
States
| | - David M. Jenkins
- Department of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996-1600, United
States
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48
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Das B, Reddy MV, Chowdari BVR. X-ray absorption spectroscopy and energy storage of Ni-doped cobalt nitride, (Ni(0.33)Co(0.67))N, prepared by a simple synthesis route. NANOSCALE 2013; 5:1961-1966. [PMID: 23360912 DOI: 10.1039/c2nr33675h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Metal nitride (Ni(0.33)Co(0.67))N nanoparticles are prepared by nitridation using NiCo(2)O(4) as a precursor material by heating at 335 °C for 2 h in flowing NH(3) + N(2) gas and characterized by X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), high resolution-transmission electron microscopy (HR-TEM), along with selective area electron diffraction (SAED) and X-ray absorption spectroscopy (XAS) techniques. The X-ray absorption near edge structure (XANES) at the Co K-edge showed that the oxidation state of cobalt is close to 3+. The (Ni(0.33)Co(0.67))N showed a shift in edge energy towards lower values due to Ni-doping to cobalt site. The Li-storage behaviour of (Ni(0.33)Co(0.67))N nanoparticles was evaluated by galvanostatic cycling and cyclic voltammetry in the cells with Li-metal as counter electrode in the voltage range of 0.005-3.0 V at ambient temperature. When cycled at 250 mA g(-1), the first-cycle reversible capacity of 700 (±5) mA h g(-1) (~1.9 moles of Li) is obtained. It showed an initial decrease in capacity until the 10(th) cycle and a stable capacity of 400 (±5) mA h g(-1) (~1.09 moles of Li) is observed at the end of the 50(th) cycle. Excellent rate capability is also shown when cycling at 500 mA g(-1) (up to 50 cycles). The materials showed excellent Li-ion insertion/extraction, with the coulombic efficiency reaching almost 99% in the range of 10-50 cycles. The average charge and discharge potentials are ~2.03 and ~1.0 V, respectively for the decomposition/formation of Li(3)N as determined by electroanalytical techniques.
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Affiliation(s)
- B Das
- Department of Physics, National University of Singapore, Singapore 117542
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49
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Lancaster KM, Hu Y, Bergmann U, Ribbe MW, DeBeer S. X-ray spectroscopic observation of an interstitial carbide in NifEN-bound FeMoco precursor. J Am Chem Soc 2013; 135:610-2. [PMID: 23276198 DOI: 10.1021/ja309254g] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The iron-molybdenum cofactor (FeMoco) of nitrogenase contains a biologically unprecedented μ(6)-coordinated C(4-) ion. Although the role of this interstitial atom in nitrogenase catalysis is unknown, progress in understanding its biosynthetic origins has been made. Here we report valence-to-core Fe Kβ X-ray emission spectroscopy data to show that this C(4-) ion is present in the Fe(8)S(9) "L-cluster," which is the immediate precursor to FeMoco prior to the insertion of molybdenum and coordination by homocitrate. These results accord with recent evidence supporting a role for the S-adenosylmethionine-dependent enzyme NifB in the incorporation of carbon into the FeMoco center of nitrogenase.
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Affiliation(s)
- Kyle M Lancaster
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
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