1
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Wojdyla Z, Srnec M. Radical ligand transfer: mechanism and reactivity governed by three-component thermodynamics. Chem Sci 2024; 15:8459-8471. [PMID: 38846394 PMCID: PMC11151871 DOI: 10.1039/d4sc01507j] [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: 03/04/2024] [Accepted: 04/19/2024] [Indexed: 06/09/2024] Open
Abstract
Here, we demonstrate that the relationship between reactivity and thermodynamics in radical ligand transfer chemistry can be understood if this chemistry is dissected as concerted ion-electron transfer (cIET). Namely, we investigate radical ligand transfer reactions from the perspective of thermodynamic contributions to the reaction barrier: the diagonal effect of the free energy of the reaction, and the off-diagonal effect resulting from asynchronicity and frustration, which we originally derived from the thermodynamic cycle for concerted proton-electron transfer (cPET). This study on the OH transfer reaction shows that the three-component thermodynamic model goes beyond cPET chemistry, successfully capturing the changes in radical ligand transfer reactivity in a series of model FeIII-OH⋯(diflouro)cyclohexadienyl systems. We also reveal the decisive role of the off-diagonal thermodynamics in determining the reaction mechanism. Two possible OH transfer mechanisms, in which electron transfer is coupled with either OH- and OH+ transfer, are associated with two competing thermodynamic cycles. Consequently, the operative mechanism is dictated by the cycle yielding a more favorable off-diagonal effect on the barrier. In line with this thermodynamic link to the mechanism, the transferred OH group in OH-/electron transfer retains its anionic character and slightly changes its volume in going from the reactant to the transition state. In contrast, OH+/electron transfer develops an electron deficiency on OH, which is evidenced by an increase in charge and a simultaneous decrease in volume. In addition, the observations in the study suggest that an OH+/electron transfer reaction can be classified as an adiabatic radical transfer, and the OH-/electron transfer reaction as a less adiabatic ion-coupled electron transfer.
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Affiliation(s)
- Zuzanna Wojdyla
- J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences Dolejškova 3 Prague 8 18223 Czech Republic
| | - Martin Srnec
- J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences Dolejškova 3 Prague 8 18223 Czech Republic
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2
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Beagan DM, Rivera C, Szymczak NK. Appended Lewis Acids Enable Dioxygen Reactivity and Catalytic Oxidations with Ni(II). J Am Chem Soc 2024; 146:12375-12385. [PMID: 38661576 PMCID: PMC11148854 DOI: 10.1021/jacs.3c12399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
We disclose a suite of Ni(II) complexes featuring secondary sphere Lewis acids of varied Lewis acidity and tether lengths. Several of these complexes feature atypical behavior of Ni(II): reactivity with O2 that occurs only in the presence of a tethered Lewis acid. In situ UV-vis spectroscopy revealed that, although adducts are stable at -40 °C, complexes containing 9-borabicyclo[3.3.1]nonane (9-BBN) Lewis acids underwent irreversible oxidative deborylation when warmed to room temperature. We computationally and experimentally identified that oxidative instability of appended 9-BBN moieties can be mitigated using weaker Lewis acids such as pinacolborane (BPin). These insights enabled the realization of catalytic reactions: hydrogen atom abstraction from phenols and room temperature oxygen atom transfer to PPh3.
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Affiliation(s)
- Daniel M Beagan
- University of Michigan, 930 N. University Ave., Ann Arbor, Michigan 48109, United States
| | - Carolina Rivera
- University of Michigan, 930 N. University Ave., Ann Arbor, Michigan 48109, United States
| | - Nathaniel K Szymczak
- University of Michigan, 930 N. University Ave., Ann Arbor, Michigan 48109, United States
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3
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Sarkar W, LaDuca A, Wilson JR, Szymczak NK. Iron-Catalyzed C-H Oxygenation Using Perchlorate Enabled by Secondary Sphere Hydrogen Bonds. J Am Chem Soc 2024; 146:10508-10516. [PMID: 38564312 PMCID: PMC11137739 DOI: 10.1021/jacs.3c14433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Perchlorate (ClO4-) is a groundwater pollutant that is challenging to remediate. We report a strategy to use Fe(II) tris(2-pyridylmethyl)amine (TPA) complexes featuring appended aniline hydrogen bonds (H-bonds) to promote ClO4- reduction. These complexes facilitate oxygen atom transfer from ClO4- to PPh3 and C-H oxygenation reactions of organic substrates. Catalytic reactions using 15 mol % afforded excellent yields for oxygenation of anthracene and cyclic alkyl aromatics, and this methodology tolerates aryl halides as well as heterocycles containing either O, S, or N.
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Affiliation(s)
- Writhabrata Sarkar
- Department of Chemistry, University of Michigan, 930 N. University, Ann Arbor, Michigan 48109, United States
| | - Andrew LaDuca
- Department of Chemistry, University of Michigan, 930 N. University, Ann Arbor, Michigan 48109, United States
| | - Jessica R Wilson
- Department of Chemistry, University of Michigan, 930 N. University, Ann Arbor, Michigan 48109, United States
| | - Nathaniel K Szymczak
- Department of Chemistry, University of Michigan, 930 N. University, Ann Arbor, Michigan 48109, United States
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4
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Yadav S, Yadav V, Siegler MA, Moënne-Loccoz P, Jameson GNL, Goldberg DP. A Nonheme Iron(III) Superoxide Complex Leads to Sulfur Oxygenation. J Am Chem Soc 2024; 146:7915-7921. [PMID: 38488295 DOI: 10.1021/jacs.3c12337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2024]
Abstract
A new alkylthiolate-ligated nonheme iron complex, FeII(BNPAMe2S)Br (1), is reported. Reaction of 1 with O2 at -40 °C, or reaction of the ferric form with O2•- at -80 °C, gives a rare iron(III)-superoxide intermediate, [FeIII(O2)(BNPAMe2S)]+ (2), characterized by UV-vis, 57Fe Mössbauer, ATR-FTIR, EPR, and CSIMS. Metastable 2 then converts to an S-oxygenated FeII(sulfinate) product via a sequential O atom transfer mechanism involving an iron-sulfenate intermediate. These results provide evidence for the feasibility of proposed intermediates in thiol dioxygenases.
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Affiliation(s)
- Sudha Yadav
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Vishal Yadav
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Maxime A Siegler
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Pierre Moënne-Loccoz
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, Oregon 97239, United States
| | - Guy N L Jameson
- School of Chemistry, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, 30 Flemington Road,Parkville, Victoria 3010, Australia
| | - David P Goldberg
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
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5
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Keshari K, Santra A, Velasco L, Sauvan M, Kaur S, Ugale AD, Munshi S, Marco JF, Moonshiram D, Paria S. Functional Model of Compound II of Cytochrome P450: Spectroscopic Characterization and Reactivity Studies of a Fe IV-OH Complex. JACS AU 2024; 4:1142-1154. [PMID: 38559734 PMCID: PMC10976569 DOI: 10.1021/jacsau.3c00844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 02/12/2024] [Accepted: 02/26/2024] [Indexed: 04/04/2024]
Abstract
Herein, we show that the reaction of a mononuclear FeIII(OH) complex (1) with N-tosyliminobenzyliodinane (PhINTs) resulted in the formation of a FeIV(OH) species (3). The obtained complex 3 was characterized by an array of spectroscopic techniques and represented a rare example of a synthetic FeIV(OH) complex. The reaction of 1 with the one-electron oxidizing agent was reported to form a ligand-oxidized FeIII(OH) complex (2). 3 revealed a one-electron reduction potential of -0.22 V vs Fc+/Fc at -15 °C, which was 150 mV anodically shifted than 2 (Ered = -0.37 V vs Fc+/Fc at -15 °C), inferring 3 to be more oxidizing than 2. 3 reacted spontaneously with (4-OMe-C6H4)3C• to form (4-OMe-C6H4)3C(OH) through rebound of the OH group and displayed significantly faster reactivity than 2. Further, activation of the hydrocarbon C-H and the phenolic O-H bond by 2 and 3 was compared and showed that 3 is a stronger oxidant than 2. A detailed kinetic study established the occurrence of a concerted proton-electron transfer/hydrogen atom transfer reaction of 3. Studying one-electron reduction of 2 and 3 using decamethylferrocene (Fc*) revealed a higher ket of 3 than 2. The study established that the primary coordination sphere around Fe and the redox state of the metal center is very crucial in controlling the reactivity of high-valent Fe-OH complexes. Further, a FeIII(OMe) complex (4) was synthesized and thoroughly characterized, including X-ray structure determination. The reaction of 4 with PhINTs resulted in the formation of a FeIV(OMe) species (5), revealing the presence of two FeIV species with isomer shifts of -0.11 mm/s and = 0.17 mm/s in the Mössbauer spectrum and showed FeIV/FeIII potential at -0.36 V vs Fc+/Fc couple in acetonitrile at -15 °C. The reactivity studies of 5 were investigated and compared with the FeIV(OH) complex (3).
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Affiliation(s)
- Kritika Keshari
- Department
of Chemistry, Indian Institute of Technology
Delhi, Hauz Khas, New Delhi 110016, India
| | - Aakash Santra
- Department
of Chemistry, Indian Institute of Technology
Delhi, Hauz Khas, New Delhi 110016, India
| | - Lucía Velasco
- Instituto
de Ciencia de Materiales de Madrid, Consejo
Superior de Investigaciones Científicas, Sor Juana Inés de la Cruz, 3, Madrid 28049, Spain
| | - Maxime Sauvan
- Instituto
de Ciencia de Materiales de Madrid, Consejo
Superior de Investigaciones Científicas, Sor Juana Inés de la Cruz, 3, Madrid 28049, Spain
| | - Simarjeet Kaur
- Department
of Chemistry, Indian Institute of Technology
Delhi, Hauz Khas, New Delhi 110016, India
| | - Ashok D. Ugale
- Instituto
de Ciencia de Materiales de Madrid, Consejo
Superior de Investigaciones Científicas, Sor Juana Inés de la Cruz, 3, Madrid 28049, Spain
| | - Sandip Munshi
- School
of Chemical Science, Indian Association
for the Cultivation of Science, Raja S C Mulliick Road, Kolkata 700032, India
| | - J. F. Marco
- Instituto
de Quimica Fisica Blas Cabrera, Consejo
Superior de Investigaciones Científicas, C. de Serrano, 119, Serrano, Madrid 28006, Spain
| | - Dooshaye Moonshiram
- Instituto
de Ciencia de Materiales de Madrid, Consejo
Superior de Investigaciones Científicas, Sor Juana Inés de la Cruz, 3, Madrid 28049, Spain
| | - Sayantan Paria
- Department
of Chemistry, Indian Institute of Technology
Delhi, Hauz Khas, New Delhi 110016, India
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6
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Kumar M, Gupta MK, Ansari M, Ansari A. C-H bond activation by high-valent iron/cobalt-oxo complexes: a quantum chemical modeling approach. Phys Chem Chem Phys 2024; 26:4349-4362. [PMID: 38235511 DOI: 10.1039/d3cp05866b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
High-valent metal-oxo species serve as key intermediates in the activation of inert C-H bonds. Here, we present a comprehensive DFT analysis of the parameters that have been proposed as influencing factors in modeled high-valent metal-oxo mediated C-H activation reactions. Our approach involves utilizing DFT calculations to explore the electronic structures of modeled FeIVO (species 1) and CoIVO ↔ CoIII-O˙ (species 2), scrutinizing their capacity to predict improved catalytic activity. DFT and DLPNO-CCSD(T) calculations predict that the iron-oxo species possesses a triplet as the ground state, while the cobalt-oxo has a doublet as the ground state. Furthermore, we have investigated the mechanistic pathways for the first C-H bond activation, as well as the desaturation of the alkanes. The mechanism was determined to be a two-step process, wherein the first hydrogen atom abstraction (HAA) represents the rate-limiting step, involving the proton-coupled electron transfer (PCET) process. However, we found that the second HAA step is highly exothermic for both species. Our calculations suggest that the iron-oxo species (Fe-O = 1.672 Å) exhibit relatively sluggish behavior compared to the cobalt-oxo species (Co-O = 1.854 Å) in C-H bond activation, attributed to a weak metal-oxygen bond. MO, NBO, and deformation energy analysis reveal the importance of weakening the M-O bond in the cobalt species, thereby reducing the overall barrier to the reaction. This catalyst was found to have a C-H activation barrier relatively smaller than that previously reported in the literature.
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Affiliation(s)
- Manjeet Kumar
- Department of Chemistry, Central University of Haryana, Mahendergarh-123031, Haryana, India.
| | - Manoj Kumar Gupta
- Department of Chemistry, Central University of Haryana, Mahendergarh-123031, Haryana, India.
| | - Mursaleem Ansari
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
| | - Azaj Ansari
- Department of Chemistry, Central University of Haryana, Mahendergarh-123031, Haryana, India.
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7
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Li Y, Abelson C, Que L, Wang D. 10 6-fold faster C-H bond hydroxylation by a Co III,IV2(µ-O) 2 complex [via a Co III2(µ-O)(µ-OH) intermediate] versus its Fe IIIFe IV analog. Proc Natl Acad Sci U S A 2023; 120:e2307950120. [PMID: 38085777 PMCID: PMC10743362 DOI: 10.1073/pnas.2307950120] [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: 05/11/2023] [Accepted: 11/04/2023] [Indexed: 12/24/2023] Open
Abstract
The hydroxylation of C-H bonds can be carried out by the high-valent CoIII,IV2(µ-O)2 complex 2a supported by the tetradentate tris(2-pyridylmethyl)amine ligand via a CoIII2(µ-O)(µ-OH) intermediate (3a). Complex 3a can be independently generated either by H-atom transfer (HAT) in the reaction of 2a with phenols as the H-atom donor or protonation of its conjugate base, the CoIII2(µ-O)2 complex 1a. Resonance Raman spectra of these three complexes reveal oxygen-isotope-sensitive vibrations at 560 to 590 cm-1 associated with the symmetric Co-O-Co stretching mode of the Co2O2 diamond core. Together with a Co•••Co distance of 2.78(2) Å previously identified for 1a and 2a by Extended X-ray Absorption Fine Structure (EXAFS) analysis, these results provide solid evidence for their "diamond core" structural assignments. The independent generation of 3a allows us to investigate HAT reactions of 2a with phenols in detail, measure the redox potential and pKa of the system, and calculate the O-H bond strength (DO-H) of 3a to shed light on the C-H bond activation reactivity of 2a. Complex 3a is found to be able to transfer its hydroxyl ligand onto the trityl radical to form the hydroxylated product, representing a direct experimental observation of such a reaction by a dinuclear cobalt complex. Surprisingly, reactivity comparisons reveal 2a to be 106-fold more reactive in oxidizing hydrocarbon C-H bonds than corresponding FeIII,IV2(µ-O)2 and MnIII,IV2(µ-O)2 analogs, an unexpected outcome that raises the prospects for using CoIII,IV2(µ-O)2 species to oxidize alkane C-H bonds.
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Affiliation(s)
- Yan Li
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT59812
| | - Chase Abelson
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN55455
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN55455
| | - Dong Wang
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT59812
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8
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Yadav V, Wen L, Yadav S, Siegler MA, Goldberg DP. Selective Radical Transfer in a Series of Nonheme Iron(III) Complexes. Inorg Chem 2023; 62:17830-17842. [PMID: 37857315 PMCID: PMC11296666 DOI: 10.1021/acs.inorgchem.3c02617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
A series of nonheme iron complexes, FeIII(BNPAPh2O)(Lax)(Leq) (Lax/eq = N3-, NCS-, NCO-, and Cl-) have been synthesized using the previously reported BNPAPh2O- ligand. The ferrous analogs FeII(BNPAPh2O)(Lax) (Lax = N3-, NCS-, and NCO-) were also prepared. The complexes were structurally characterized using single crystal X-ray diffraction, which shows that all the FeIII complexes are six-coordinate, with one anionic ligand (Lax) in the H-bonding axial site and the other anionic ligand (Leq) in the equatorial plane, cis to the Lax ligand. The reaction of FeIII(BNPAPh2O-)(Lax)(Leq) with Ph3C• shows that one ligand is selectively transferred in each case. A selectivity trend emerges that shows •N3 is the most favored for transfer in each case to the carbon radical, whereas Cl• is the least favored. The NCO and NCS ligands showed an intermediate propensity for radical transfer, with NCS > NCO. The overall order of selectivity is N3 > NCS > NCO > Cl. In addition, we also demonstrated that H-bonding has a small effect on governing product selectivity by using a non-H-bonded ligand (DPAPh2O-). This study demonstrates the inherent radical transfer selectivity of nonhydroxo-ligated nonheme iron(III) complexes, which could be useful for efforts in synthetic and (bio)catalytic C-H functionalization.
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Affiliation(s)
- Vishal Yadav
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Lyupeng Wen
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Sudha Yadav
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Maxime A Siegler
- 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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9
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Panda C, Anny-Nzekwue O, Doyle LM, Gericke R, McDonald AR. Evidence for a High-Valent Iron-Fluoride That Mediates Oxidative C(sp 3)-H Fluorination. JACS AU 2023; 3:919-928. [PMID: 37006763 PMCID: PMC10052241 DOI: 10.1021/jacsau.3c00021] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 02/14/2023] [Accepted: 02/15/2023] [Indexed: 06/19/2023]
Abstract
[FeII(NCCH3)(NTB)](OTf)2 (NTB = tris(2-benzimidazoylmethyl)amine, OTf = trifluoromethanesulfonate) was reacted with difluoro(phenyl)-λ3-iodane (PhIF2) in the presence of a variety of saturated hydrocarbons, resulting in the oxidative fluorination of the hydrocarbons in moderate-to-good yields. Kinetic and product analysis point towards a hydrogen atom transfer oxidation prior to fluorine radical rebound to form the fluorinated product. The combined evidence supports the formation of a formally FeIV(F)2 oxidant that performs hydrogen atom transfer followed by the formation of a dimeric μ-F-(FeIII)2 product that is a plausible fluorine atom transfer rebound reagent. This approach mimics the heme paradigm for hydrocarbon hydroxylation, opening up avenues for oxidative hydrocarbon halogenation.
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10
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Yadav V, Wen L, Rodriguez RJ, Siegler MA, Goldberg DP. Nonheme Iron(III) Azide and Iron(III) Isothiocyanate Complexes: Radical Rebound Reactivity, Selectivity, and Catalysis. J Am Chem Soc 2022; 144:20641-20652. [PMID: 36382466 PMCID: PMC10226418 DOI: 10.1021/jacs.2c07224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The new nonheme iron complexes FeII(BNPAPh2O)(N3) (1), FeIII(BNPAPh2O)(OH)(N3) (2), FeII(BNPAPh2O)(OH) (3), FeIII(BNPAPh2O)(OH)(NCS) (4), FeII(BNPAPh2O)(NCS) (5), FeIII(BNPAPh2O)(NCS)2 (6), and FeIII(BNPAPh2O)(N3)2 (7) (BNPAPh2O = 2-(bis((6-(neopentylamino)pyridin-2-yl) methyl)amino)-1,1-diphenylethanolate) were synthesized and characterized by single crystal X-ray diffraction (XRD), as well as by 1H NMR, 57Fe Mössbauer, and ATR-IR spectroscopies. Complex 2 was reacted with a series of carbon radicals, ArX3C· (ArX = p-X-C6H4), analogous to the proposed radical rebound step for nonheme iron hydroxylases and halogenases. The results show that for ArX3C· (X = Cl, H, tBu), only OH· transfer occurs to give ArX3COH. However, when X = OMe, a mixture of alcohol (ArX3COH) (30%) and azide (ArX3CN3) (40%) products was obtained. These data indicate that the rebound selectivity is influenced by the electron-rich nature of the carbon radicals for the azide complex. Reaction of 2 with Ph3C· in the presence of Sc3+ or H+ reverses the selectivity, giving only the azide product. In contrast to the mixed selectivity seen for 2, the reactivity of cis-FeIII(OH)(NCS) with the X = OMe radical derivative leads only to hydroxylation. Catalytic azidation was achieved with 1 as catalyst, λ3-azidoiodane as oxidant and azide source, and Ph3CH as test substrate, giving Ph3CN3 in 84% (TON = 8). These studies show that hydroxylation is favored over azidation for nonheme iron(III) complexes, but the nature of the carbon radical can alter this selectivity. If an OH· transfer pathway can be avoided, the FeIII(N3) complexes are capable of mediating both stoichiometric and catalytic azidation.
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Affiliation(s)
- Vishal Yadav
- Department of Chemistry, The Johns Hopkins
University, 3400 North Charles Street, Baltimore, Maryland, 21218, USA
| | - Lyupeng Wen
- Department of Chemistry, The Johns Hopkins
University, 3400 North Charles Street, Baltimore, Maryland, 21218, USA
| | - Rodolfo J. Rodriguez
- Department of Chemistry, The Johns Hopkins
University, 3400 North Charles Street, Baltimore, Maryland, 21218, USA
| | - Maxime A. Siegler
- Department of Chemistry, The Johns Hopkins
University, 3400 North Charles Street, Baltimore, Maryland, 21218, USA
| | - David P. Goldberg
- Department of Chemistry, The Johns Hopkins
University, 3400 North Charles Street, Baltimore, Maryland, 21218, USA
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11
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Nandy A, Adamji H, Kastner DW, Vennelakanti V, Nazemi A, Liu M, Kulik HJ. Using Computational Chemistry To Reveal Nature’s Blueprints for Single-Site Catalysis of C–H Activation. ACS Catal 2022. [DOI: 10.1021/acscatal.2c02096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Aditya Nandy
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Husain Adamji
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - David W. Kastner
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Vyshnavi Vennelakanti
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Azadeh Nazemi
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Mingjie Liu
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Heather J. Kulik
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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12
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Gérard EF, Yadav V, Goldberg DP, de Visser SP. What Drives Radical Halogenation versus Hydroxylation in Mononuclear Nonheme Iron Complexes? A Combined Experimental and Computational Study. J Am Chem Soc 2022; 144:10752-10767. [PMID: 35537044 PMCID: PMC9228086 DOI: 10.1021/jacs.2c01375] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
![]()
Nonheme iron halogenases
are unique enzymes in nature that selectively
activate an aliphatic C–H bond of a substrate to convert it
into C–X (X = Cl/Br, but not F/I). It is proposed that they
generate an FeIII(OH)(X) intermediate in their catalytic
cycle. The analogous FeIII(OH) intermediate in nonheme
iron hydroxylases transfers OH• to give alcohol
product, whereas the halogenases transfer X• to
the carbon radical substrate. There remains significant debate regarding
what factors control their remarkable selectivity of the halogenases.
The reactivity of the complexes FeIII(BNPAPh2O)(OH)(X) (X = Cl, Br) with a secondary carbon radical (R•) is described. It is found that X• transfer occurs
with a secondary carbon radical, as opposed to OH• transfer with tertiary radicals. Comprehensive computational studies
involving density functional theory were carried out to examine the
possible origins of this selectivity. The calculations reproduce the
experimental findings, which indicate that halogen transfer is not
observed for the tertiary radicals because of a nonproductive equilibrium
that results from the endergonic nature of these reactions, despite
a potentially lower reaction barrier for the halogenation pathway.
In contrast, halogen transfer is favored for secondary carbon radicals,
for which the halogenated product complex is thermodynamically more
stable than the reactant complex. These results are rationalized by
considering the relative strengths of the C–X bonds that are
formed for tertiary versus secondary carbon centers. The computational
analysis also shows that the reaction barrier for halogen transfer
is significantly dependent on secondary coordination sphere effects,
including steric and H-bonding interactions.
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Affiliation(s)
- Emilie F Gérard
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom.,Department of Chemical Engineering, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Vishal Yadav
- 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
| | - Sam P de Visser
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom.,Department of Chemical Engineering, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
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13
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Dedushko MA, Greiner MB, Downing AN, Coggins M, Kovacs JA. Electronic Structure and Reactivity of Dioxygen-Derived Aliphatic Thiolate-Ligated Fe-Peroxo and Fe(IV) Oxo Compounds. J Am Chem Soc 2022; 144:8515-8528. [PMID: 35522532 DOI: 10.1021/jacs.1c07656] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Herein, we examine the electronic and geometric structural properties of O2-derived aliphatic thiolate-ligated Fe-peroxo, Fe-hydroxo, and Fe(IV) oxo compounds. The latter cleaves strong C-H bonds (96 kcal mol-1) on par with the valine C-H bond cleaved by isopencillin N synthase (IPNS). Stopped-flow kinetics studies indicate that the barrier to O2 binding to [FeII(SMe2N4(tren))]+ (3) is extremely low (Ea = 36(2) kJ mol-1), as theoretically predicted for IPNS. Dioxygen binding to 3 is shown to be reversible, and a superoxo intermediate, [FeIII(SMe2N4(tren))(O2)]+ (6), forms in the first 25 ms of the reaction at -40 °C prior to the rate-determining (Ea = 46(2) kJ mol-1) formation of peroxo-bridged [(SMe2N4(tren))Fe(III)]2(μ-O2)2+ (7). A log(kobs) vs log([Fe]) plot for the formation of 7 is consistent with the second-order dependence on iron, and H2O2 assays are consistent with a 2:1 ratio of Fe/H2O2. Peroxo 7 is shown to convert to ferric-hydroxo [FeIII(SMe2N(tren))(OH)]+ (9, g⊥ = 2.24, g∥ = 1.96), the identity of which was determined via its independent synthesis. Rates of the conversion 7 → 9 are shown to be dependent on the X-H bond strength of the H-atom donor, with a kH/kD = 4 when CD3OD is used in place of CH3OH as a solvent. A crystallographically characterized cis thiolate-ligated high-valent iron oxo, [FeIV(O)(SMe2N4(tren))]+ (11), is shown to form en route to hydroxo 9. Electronic structure calculations were shown to be consistent with 11 being an S = 1 Fe(IV)═O with an unusually high νFe-O stretching frequency at 918 cm-1 in line with the extremely short Fe-O bond (1.603(7) Å).
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Affiliation(s)
- Maksym A Dedushko
- Department of Chemistry, University of Washington, Campus Box 351700, Seattle, Washington 98195-1700, United States
| | - Maria B Greiner
- Department of Chemistry, University of Washington, Campus Box 351700, Seattle, Washington 98195-1700, United States
| | - Alexandra N Downing
- Department of Chemistry, University of Washington, Campus Box 351700, Seattle, Washington 98195-1700, United States
| | - Michael Coggins
- Department of Chemistry, University of Washington, Campus Box 351700, Seattle, Washington 98195-1700, United States
| | - Julie A Kovacs
- Department of Chemistry, University of Washington, Campus Box 351700, Seattle, Washington 98195-1700, United States
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14
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Posada-Pérez S, Escayola S, Poater J, Solà M, Poater A. Ni(I)-TPA Stabilization by Hydrogen Bond formation on the Second Coordination Sphere: a DFT Characterization. Dalton Trans 2022; 51:12585-12595. [DOI: 10.1039/d2dt01355j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ni(I) compounds are less common than those of either Ni(0) or Ni(II). Recently, a series of Ni(I) tris(2 pyridylmethyl)amine (TPA) complexes were synthetized through the reduction of Ni(II)-TPA complexes and...
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15
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Lee JL, Ross DL, Barman SK, Ziller JW, Borovik AS. C-H Bond Cleavage by Bioinspired Nonheme Metal Complexes. Inorg Chem 2021; 60:13759-13783. [PMID: 34491738 DOI: 10.1021/acs.inorgchem.1c01754] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The functionalization of C-H bonds is one of the most challenging transformations in synthetic chemistry. In biology, these processes are well-known and are achieved with a variety of metalloenzymes, many of which contain a single metal center within their active sites. The most well studied are those with Fe centers, and the emerging experimental data show that high-valent iron oxido species are the intermediates responsible for cleaving the C-H bond. This Forum Article describes the state of this field with an emphasis on nonheme Fe enzymes and current experimental results that provide insights into the properties that make these species capable of C-H bond cleavage. These parameters are also briefly considered in regard to manganese oxido complexes and Cu-containing metalloenzymes. Synthetic iron oxido complexes are discussed to highlight their utility as spectroscopic and mechanistic probes and reagents for C-H bond functionalization. Avenues for future research are also examined.
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Affiliation(s)
- Justin L Lee
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Dolores L Ross
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Suman K Barman
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Joseph W Ziller
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - A S Borovik
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
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16
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Leahy CA, Drummond MJ, Vura-Weis J, Fout AR. Synthesis of a series of M(II) (M = Mn, Fe, Co) chloride complexes with both inter- and intra-ligand hydrogen bonding interactions. Dalton Trans 2021; 50:12088-12092. [PMID: 34519757 DOI: 10.1039/d1dt02585f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hydrogen bonding networks are vital for metallo-enzymes to function; however, modeling these systems is non-trivial. We report the synthesis of metal chloride (M = Mn, Fe, Co) complexes with intra- and inter-ligand hydrogen bonding interactions. The intra-ligand hydrogen bonds are shown to have a profound effect on the geometry of the metal center.
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Affiliation(s)
- Clare A Leahy
- School of Chemical Sciences, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, Illinois 61801, USA.
| | - Michael J Drummond
- School of Chemical Sciences, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, Illinois 61801, USA.
| | - Josh Vura-Weis
- School of Chemical Sciences, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, Illinois 61801, USA.
| | - Alison R Fout
- School of Chemical Sciences, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, Illinois 61801, USA.
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17
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Dobbelaar E, Rauber C, Bonck T, Kelm H, Schmitz M, de Waal Malefijt ME, Klein JEMN, Krüger HJ. Combining Structural with Functional Model Properties in Iron Synthetic Analogue Complexes for the Active Site in Rabbit Lipoxygenase. J Am Chem Soc 2021; 143:13145-13155. [PMID: 34383499 DOI: 10.1021/jacs.1c04422] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Iron complexes that model the structural and functional properties of the active iron site in rabbit lipoxygenase are described. The ligand sphere of the mononuclear pseudo-octahedral cis-(carboxylato)(hydroxo)iron(III) complex, which is completed by a tetraazamacrocyclic ligand, reproduces the first coordination shell of the active site in the enzyme. In addition, two corresponding iron(II) complexes are presented that differ in the coordination of a water molecule. In their structural and electronic properties, both the (hydroxo)iron(III) and the (aqua)iron(II) complex reflect well the only two essential states found in the enzymatic mechanism of peroxidation of polyunsaturated fatty acids. Furthermore, the ferric complex is shown to undergo hydrogen atom abstraction reactions with O-H and C-H bonds of suitable substrates, and the bond dissociation free energy of the coordinated water ligand of the ferrous complex is determined to be 72.4 kcal·mol-1. Theoretical investigations of the reactivity support a concerted proton-coupled electron transfer mechanism in close analogy to the initial step in the enzymatic mechanism. The propensity of the (hydroxo)iron(III) complex to undergo H atom abstraction reactions is the basis for its catalytic function in the aerobic peroxidation of 2,4,6-tri(tert-butyl)phenol and its role as a radical initiator in the reaction of dihydroanthracene with oxygen.
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Affiliation(s)
- Emiel Dobbelaar
- Department of Chemistry, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Christian Rauber
- Department of Chemistry, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Thorsten Bonck
- Department of Chemistry, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Harald Kelm
- Department of Chemistry, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Markus Schmitz
- Department of Chemistry, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Matina Eloïse de Waal Malefijt
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 9, 9747 AG Groningen, The Netherlands
| | - Johannes E M N Klein
- Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 9, 9747 AG Groningen, The Netherlands
| | - Hans-Jörg Krüger
- Department of Chemistry, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
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18
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Mukherjee G, Satpathy JK, Bagha UK, Mubarak MQE, Sastri CV, de Visser SP. Inspiration from Nature: Influence of Engineered Ligand Scaffolds and Auxiliary Factors on the Reactivity of Biomimetic Oxidants. ACS Catal 2021. [DOI: 10.1021/acscatal.1c01993] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Gourab Mukherjee
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039, Assam, India
| | - Jagnyesh K. Satpathy
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039, Assam, India
| | - Umesh K. Bagha
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039, Assam, India
| | - M. Qadri E. Mubarak
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
- Fakulti Sains dan Teknologi, Universiti Sains Islam Malaysia, Bandar Baru Nilai, 71800 Nilai, Negeri Sembilan Malaysia
| | - Chivukula V. Sastri
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039, Assam, India
| | - Sam P. de Visser
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039, Assam, India
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
- Department of Chemical Engineering and Analytical Science, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
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19
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Keshari K, Bera M, Velasco L, Munshi S, Gupta G, Moonshiram D, Paria S. Characterization and reactivity study of non-heme high-valent iron-hydroxo complexes. Chem Sci 2021; 12:4418-4424. [PMID: 34163706 PMCID: PMC8179568 DOI: 10.1039/d0sc07054h] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A terminal FeIIIOH complex, [FeIII(L)(OH)]2− (1), has been synthesized and structurally characterized (H4L = 1,2-bis(2-hydroxy-2-methylpropanamido)benzene). The oxidation reaction of 1 with one equiv. of tris(4-bromophenyl)ammoniumyl hexachloroantimonate (TBAH) or ceric ammonium nitrate (CAN) in acetonitrile at −45 °C results in the formation of a FeIIIOH ligand radical complex, [FeIII(L˙)(OH)]− (2), which is hereby characterized by UV-visible, 1H nuclear magnetic resonance, electron paramagnetic resonance, and X-ray absorption spectroscopy techniques. The reaction of 2 with a triphenylcarbon radical further gives triphenylmethanol and mimics the so-called oxygen rebound step of Cpd II of cytochrome P450. Furthermore, the reaction of 2 was explored with different 4-substituted-2,6-di-tert-butylphenols. Based on kinetic analysis, a hydrogen atom transfer (HAT) mechanism has been established. A pKa value of 19.3 and a BDFE value of 78.2 kcal/mol have been estimated for complex 2. One-electron oxidation of an FeIII–OH complex (1) results in the formation of a FeIII–OH ligand radical complex (2). Its reaction with (C6H5)3C˙ results in the formation of (C6H5)3COH, which is a functional mimic of compound II of cytochrome P450.![]()
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Affiliation(s)
- Kritika Keshari
- Department of Chemistry, Indian Institute of Technology Delhi Hauz Khas New Delhi 110016 India
| | - Moumita Bera
- Department of Chemistry, Indian Institute of Technology Delhi Hauz Khas New Delhi 110016 India
| | - Lucía Velasco
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia Calle Faraday, 9 28049 Madrid Spain
| | - Sandip Munshi
- School of Chemical Sciences, Indian Association for the Cultivation of Science 2A & 2B Raja S. C. Mullick Road, Jadavpur Kolkata 700032 India
| | - Geetika Gupta
- Department of Chemistry, Indian Institute of Technology Delhi Hauz Khas New Delhi 110016 India
| | - Dooshaye Moonshiram
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia Calle Faraday, 9 28049 Madrid Spain
| | - Sayantan Paria
- Department of Chemistry, Indian Institute of Technology Delhi Hauz Khas New Delhi 110016 India
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20
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Abstract
A series of nickel(ii) tris(2-pyridylmethyl)amine (TPA) complexes featuring appended hydrogen bonds (H-bonds) to halides (F, Cl, Br) was synthesized and charcterized. Reduction to the nickel(i) state provided access to an unusual nickel(i) fluoride complex stabilized by H-bonds, enabling structural and spectroscopic characterization.
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Affiliation(s)
- Jessica R Wilson
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.
| | - Matthias Zeller
- H.C. Brown Laboratory, Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA
| | - Nathaniel K Szymczak
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.
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21
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Yadav V, Siegler MA, Goldberg DP. Temperature-Dependent Reactivity of a Non-heme Fe III(OH)(SR) Complex: Relevance to Isopenicillin N Synthase. J Am Chem Soc 2021; 143:46-52. [PMID: 33356198 DOI: 10.1021/jacs.0c09688] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Non-heme iron complexes with cis-FeIII(OH)(SAr/OAr) coordination were isolated and examined for their reactivity with a tertiary carbon radical. The sulfur-ligated complex shows a temperature dependence on •OH versus ArS• transfer, whereas the oxygen-ligated complex does not. These results provide the first working model for C-S bond formation in isopenicillin N synthase and indicate that kinetic control may be a key factor in the selectivity of non-heme iron "rebound" processes.
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Affiliation(s)
- Vishal Yadav
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Maxime A Siegler
- 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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22
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Wang S, Gong L, El Fakhri G, Wang J. Efficient synthesis of 6,6′-diamido-2,2′-dipicolylamine ligands for potential phosphate anion sensing. NEW J CHEM 2021; 45:16833-16840. [DOI: 10.1039/d1nj03030b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Through retrosynthetic analysis, functionalized 6,6′-diamido-2,2′-dipicolylamines (DA-DPAs) have been efficiently synthesized, which may accelerate the development of selective probes towards phosphate anions.
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Affiliation(s)
- Shuai Wang
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 125 Nashua Street, Suite 660, Boston, Massachusetts 02114, USA
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Lichong Gong
- Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, 149 Thirteenth Street, Suite 2301, Charlestown, Massachusetts 02129, USA
| | - Georges El Fakhri
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 125 Nashua Street, Suite 660, Boston, Massachusetts 02114, USA
| | - Junfeng Wang
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, 125 Nashua Street, Suite 660, Boston, Massachusetts 02114, USA
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23
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Cummins DC, Alvarado JG, Zaragoza JPT, Effendy Mubarak MQ, Lin YT, de Visser SP, Goldberg DP. Hydroxyl Transfer to Carbon Radicals by Mn(OH) vs Fe(OH) Corrole Complexes. Inorg Chem 2020; 59:16053-16064. [PMID: 33047596 DOI: 10.1021/acs.inorgchem.0c02640] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The transfer of •OH from metal-hydroxo species to carbon radicals (R•) to give hydroxylated products (ROH) is a fundamental process in metal-mediated heme and nonheme C-H bond oxidations. This step, often referred to as the hydroxyl "rebound" step, is typically very fast, making direct study of this process challenging if not impossible. In this report, we describe the reactions of the synthetic models M(OH)(ttppc) (M = Fe (1), Mn (3); ttppc = 5,10,15-tris(2,4,6-triphenyl)phenyl corrolato3-) with a series of triphenylmethyl carbon radical (R•) derivatives ((4-X-C6H4)3C•; X = OMe, tBu, Ph, Cl, CN) to give the one-electron reduced MIII(ttppc) complexes and ROH products. Rate constants for 3 for the different radicals ranged from 11.4(1) to 58.4(2) M-1 s-1, as compared to those for 1, which fall between 0.74(2) and 357(4) M-1 s-1. Linear correlations for Hammett and Marcus plots for both Mn and Fe were observed, and the small magnitudes of the slopes for both correlations imply a concerted •OH transfer reaction for both metals. Eyring analyses of reactions for 1 and 3 with (4-X-C6H4)3C• (X = tBu, CN) also give good linear correlations, and a comparison of the resulting activation parameters highlight the importance of entropy in these •OH transfer reactions. Density functional theory calculations of the reaction profiles show a concerted process with one transition state for all radicals investigated and help to explain the electronic features of the OH rebound process.
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Affiliation(s)
- Daniel C Cummins
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Jessica G Alvarado
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Jan Paulo T Zaragoza
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Muhammad Qadri Effendy Mubarak
- Manchester Institute of Biotechnology and Department of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Yen-Ting Lin
- Manchester Institute of Biotechnology and Department of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Sam P de Visser
- Manchester Institute of Biotechnology and Department of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - David P Goldberg
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
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24
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Meunier A, Singleton ML, Kauffmann B, Granier T, Lautrette G, Ferrand Y, Huc I. Aromatic foldamers as scaffolds for metal second coordination sphere design. Chem Sci 2020; 11:12178-12186. [PMID: 34094430 PMCID: PMC8162952 DOI: 10.1039/d0sc05143h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 10/11/2020] [Indexed: 11/21/2022] Open
Abstract
As metalloproteins exemplify, the chemical and physical properties of metal centers depend not only on their first but also on their second coordination sphere. Installing arrays of functional groups around the first coordination sphere of synthetic metal complexes is thus highly desirable, but it remains a challenging objective. Here we introduce a novel approach to produce tailored second coordination spheres. We used bioinspired artificial architectures based on aromatic oligoamide foldamers to construct a rigid, modular and well-defined environment around a metal complex. Specifically, aza-aromatic monomers having a tethered [2Fe-2S] cluster have been synthesized and incorporated in conical helical foldamer sequences. Exploiting the modularity and predictability of aromatic oligoamide structures allowed for the straightforward design of a conical architecture able to sequester the metal complex in a confined environment. Even though no direct metal complex-foldamer interactions were purposely designed in this first generation model, crystallography, NMR and IR spectroscopy concurred to show that the aromatic oligoamide backbone alters the structure and fluxional processes of the metal cluster.
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Affiliation(s)
- Antoine Meunier
- Université de Bordeaux, CNRS, Bordeaux Institut National Polytechnique, CBMN (UMR 5248), IECB 2 Rue Robert Escarpit 33600 Pessac France
| | - Michael L Singleton
- Université de Bordeaux, CNRS, Bordeaux Institut National Polytechnique, CBMN (UMR 5248), IECB 2 Rue Robert Escarpit 33600 Pessac France
| | - Brice Kauffmann
- Université de Bordeaux, CNRS, INSERM, Institut Européen de Chimie et Biologie (UMS 3033) 2 Rue Robert Escarpit 33600 Pessac France
| | - Thierry Granier
- Université de Bordeaux, CNRS, Bordeaux Institut National Polytechnique, CBMN (UMR 5248), IECB 2 Rue Robert Escarpit 33600 Pessac France
| | - Guillaume Lautrette
- Université de Bordeaux, CNRS, Bordeaux Institut National Polytechnique, CBMN (UMR 5248), IECB 2 Rue Robert Escarpit 33600 Pessac France
| | - Yann Ferrand
- Université de Bordeaux, CNRS, Bordeaux Institut National Polytechnique, CBMN (UMR 5248), IECB 2 Rue Robert Escarpit 33600 Pessac France
| | - Ivan Huc
- Université de Bordeaux, CNRS, Bordeaux Institut National Polytechnique, CBMN (UMR 5248), IECB 2 Rue Robert Escarpit 33600 Pessac France
- Department of Pharmacy, Centre for Integrated Protein Science, Ludwig-Maximilians-Universität Butenandtstraße 5-13 D-81377 Munich Germany
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25
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Mayfield JR, Grotemeyer EN, Jackson TA. Concerted proton-electron transfer reactions of manganese-hydroxo and manganese-oxo complexes. Chem Commun (Camb) 2020; 56:9238-9255. [PMID: 32578605 PMCID: PMC7429365 DOI: 10.1039/d0cc01201g] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The enzymes manganese superoxide dismutase and manganese lipoxygenase use MnIII-hydroxo centres to mediate proton-coupled electron transfer (PCET) reactions with substrate. As manganese is earth-abundant and inexpensive, manganese catalysts are of interest for synthetic applications. Recent years have seen exciting reports of enantioselective C-H bond oxidation by Mn catalysts supported by aminopyridyl ligands. Such catalysts offer economic and environmentally-friendly alternatives to conventional reagents and catalysts. Mechanistic studies of synthetic catalysts highlight the role of Mn-oxo motifs in attacking substrate C-H bonds, presumably by a concerted proton-electron transfer (CPET) step. (CPET is a sub-class of PCET, where the proton and electron are transferred in the same step.) Knowledge of geometric and electronic influences for CPET reactions of Mn-hydroxo and Mn-oxo adducts enhances our understanding of biological and synthetic manganese centers and informs the design of new catalysts. In this Feature article, we describe kinetic, spectroscopic, and computational studies of MnIII-hydroxo and MnIV-oxo complexes that provide insight into the basis for the CPET reactivity of these species. Systematic perturbations of the ligand environment around MnIII-hydroxo and MnIV-oxo motifs permit elucidation of structure-activity relationships. For MnIII-hydroxo centers, electron-deficient ligands enhance oxidative reactivity. However, ligand perturbations have competing consequences, as changes in the MnIII/II potential, which represents the electron-transfer component for CPET, is offset by compensating changes in the pKa of the MnII-aqua product, which represents the proton-transfer component for CPET. For MnIV-oxo systems, a multi-state reactivity model inspired the development of significantly more reactive complexes. Weakened equatorial donation to the MnIV-oxo unit results in large rate enhancements for C-H bond oxidation and oxygen-atom transfer reactions. These results demonstrate that the local coordination environment can be rationally changed to enhance reactivity of MnIII-hydroxo and MnIV-oxo adducts.
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Affiliation(s)
- Jaycee R Mayfield
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, University of Kansas, Lawrence, KS 66045, USA.
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26
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Shanahan JP, Mullis DM, Zeller M, Szymczak NK. Reductively Stable Hydrogen-Bonding Ligands Featuring Appended CF2–H Units. J Am Chem Soc 2020; 142:8809-8817. [DOI: 10.1021/jacs.0c01718] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- James P. Shanahan
- Department of Chemistry, University of Michigan, 930 N. University, Ann Arbor, Michigan 48109, United States
| | - Danielle M. Mullis
- Department of Chemistry, University of Michigan, 930 N. University, Ann Arbor, Michigan 48109, United States
| | - Matthias Zeller
- H. C. Brown Laboratory, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Nathaniel K. Szymczak
- Department of Chemistry, University of Michigan, 930 N. University, Ann Arbor, Michigan 48109, United States
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27
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Yadav V, Rodriguez RJ, Siegler MA, Goldberg DP. Determining the Inherent Selectivity for Carbon Radical Hydroxylation versus Halogenation with Fe III(OH)(X) Complexes: Relevance to the Rebound Step in Non-heme Iron Halogenases. J Am Chem Soc 2020; 142:7259-7264. [PMID: 32281794 DOI: 10.1021/jacs.0c00493] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The first structural models of the proposed cis-FeIII(OH)(halide) intermediate in the non-heme iron halogenases were synthesized and examined for their inherent reactivity with tertiary carbon radicals. Selective hydroxylation occurs for these cis-FeIII(OH)(X) (X = Cl, Br) complexes in a radical rebound-like process. In contrast, a cis-FeIII(Cl)2 complex reacts with carbon radicals to give halogenation. These results are discussed in terms of the inherent reactivity of the analogous rebound intermediate in both enzymes and related catalysts.
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Affiliation(s)
- Vishal Yadav
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Rodolfo J Rodriguez
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Maxime A Siegler
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - David P Goldberg
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
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28
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Park H, Lee D. Ligand Taxonomy for Bioinorganic Modeling of Dioxygen-Activating Non-Heme Iron Enzymes. Chemistry 2020; 26:5916-5926. [PMID: 31909506 DOI: 10.1002/chem.201904975] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 01/04/2020] [Indexed: 12/15/2022]
Abstract
Novel functions emerge from novel structures. To develop efficient catalytic systems for challenging chemical transformations, chemists often seek inspirations from enzymatic catalysis. A large number of iron complexes supported by nitrogen-rich multidentate ligands have thus been developed to mimic oxo-transfer reactivity of dioxygen-activating metalloenzymes. Such efforts have significantly advanced our understanding of the reaction mechanisms by trapping key intermediates and elucidating their geometric and electronic properties. Critical to the success of this biomimetic approach is the design and synthesis of elaborate ligand systems to balance the thermodynamic stability, structural adaptability, and chemical reactivity. In this Concept article, representative design strategies for biomimetic atom-transfer chemistry are discussed from the perspectives of "ligand builders". Emphasis is placed on how the primary coordination sphere is constructed, and how it can be elaborated further by rational design for desired functions.
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Affiliation(s)
- Hyunchang Park
- Department of Chemistry, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Korea
| | - Dongwhan Lee
- Department of Chemistry, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Korea
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29
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Gordon Z, Miller TJ, Leahy CA, Matson EM, Burgess M, Drummond MJ, Popescu CV, Smith CM, Lord RL, Rodríguez-López J, Fout AR. Characterization of Terminal Iron(III)-Oxo and Iron(III)-Hydroxo Complexes Derived from O 2 Activation. Inorg Chem 2019; 58:15801-15811. [PMID: 31714068 DOI: 10.1021/acs.inorgchem.9b02079] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
O2 activation at nonheme iron centers is a common motif in biological systems. While synthetic models have provided numerous insights into the reactivity of high-valent iron-oxo complexes related to biological processes, the majority of these complexes are synthesized using alternative oxidants. This report describes O2 activation by an iron(II)-triflate complex of the imino-functionalized tris(pyrrol-2-ylmethyl)amine ligand framework, H3[N(piCy)3]. Initial reaction conditions result in the formation of a mixture of oxidation products including terminal iron(III)-oxo and iron(III)-hydroxo complexes. The relevance of these species to the O2 activation process is demonstrated through reactivity studies and electrochemical analysis of the iron(III)-oxo complex.
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Affiliation(s)
- Zachary Gordon
- Department of Chemistry , University of Illinois at Urbana-Champaign , 600 South Mathews Avenue , Urbana , Illinois 61801 , United States
| | - Tabitha J Miller
- Department of Chemistry , University of Illinois at Urbana-Champaign , 600 South Mathews Avenue , Urbana , Illinois 61801 , United States
| | - Clare A Leahy
- Department of Chemistry , University of Illinois at Urbana-Champaign , 600 South Mathews Avenue , Urbana , Illinois 61801 , United States
| | - Ellen M Matson
- Department of Chemistry , University of Illinois at Urbana-Champaign , 600 South Mathews Avenue , Urbana , Illinois 61801 , United States
| | - Mark Burgess
- Department of Chemistry , University of Illinois at Urbana-Champaign , 600 South Mathews Avenue , Urbana , Illinois 61801 , United States
| | - Michael J Drummond
- Department of Chemistry , University of Illinois at Urbana-Champaign , 600 South Mathews Avenue , Urbana , Illinois 61801 , United States
| | - Codrina V Popescu
- Department of Chemistry , University of St. Thomas , 2115 Summit Avenue , St. Paul , Minnesota 55105 , United States
| | - Connor M Smith
- Department of Chemistry , University of St. Thomas , 2115 Summit Avenue , St. Paul , Minnesota 55105 , United States
| | - Richard L Lord
- Department of Chemistry , Grand Valley State University , 1 Campus Drive Allendale , Michigan 49401 , United States
| | - Joaquín Rodríguez-López
- Department of Chemistry , University of Illinois at Urbana-Champaign , 600 South Mathews Avenue , Urbana , Illinois 61801 , United States
| | - Alison R Fout
- Department of Chemistry , University of Illinois at Urbana-Champaign , 600 South Mathews Avenue , Urbana , Illinois 61801 , United States
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30
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Gordon JB, Vilbert AC, DiMucci IM, MacMillan SN, Lancaster KM, Moënne-Loccoz P, Goldberg DP. Activation of Dioxygen by a Mononuclear Nonheme Iron Complex: Sequential Peroxo, Oxo, and Hydroxo Intermediates. J Am Chem Soc 2019; 141:17533-17547. [PMID: 31647656 DOI: 10.1021/jacs.9b05274] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The activation of dioxygen by FeII(Me3TACN)(S2SiMe2) (1) is reported. Reaction of 1 with O2 at -135 °C in 2-MeTHF generates a thiolate-ligated (peroxo)diiron complex FeIII2(O2)(Me3TACN)2(S2SiMe2)2 (2) that was characterized by UV-vis (λmax = 300, 390, 530, 723 nm), Mössbauer (δ = 0.53, |ΔEQ| = 0.76 mm s-1), resonance Raman (RR) (ν(O-O) = 849 cm-1), and X-ray absorption (XAS) spectroscopies. Complex 2 is distinct from the outer-sphere oxidation product 1ox (UV-vis (λmax = 435, 520, 600 nm), Mössbauer (δ = 0.45, |ΔEQ| = 3.6 mm s-1), and EPR (S = 5/2, g = [6.38, 5.53, 1.99])), obtained by one-electron oxidation of 1. Cleavage of the peroxo O-O bond can be initiated either photochemically or thermally to produce a new species assigned as an FeIV(O) complex, FeIV(O)(Me3TACN)(S2SiMe2) (3), which was identified by UV-vis (λmax = 385, 460, 890 nm), Mössbauer (δ = 0.21, |ΔEQ| = 1.57 mm s-1), RR (ν(FeIV═O) = 735 cm-1), and X-ray absorption spectroscopies, as well as reactivity patterns. Reaction of 3 at low temperature with H atom donors gives a new species, FeIII(OH)(Me3TACN)(S2SiMe2) (4). Complex 4 was independently synthesized from 1 by the stoichiometric addition of a one-electron oxidant and a hydroxide source. This work provides a rare example of dioxygen activation at a mononuclear nonheme iron(II) complex that produces both FeIII-O-O-FeIII and FeIV(O) species in the same reaction with O2. It also demonstrates the feasibility of forming Fe/O2 intermediates with strongly donating sulfur ligands while avoiding immediate sulfur oxidation.
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Affiliation(s)
- Jesse B Gordon
- Department of Chemistry , The Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
| | - Avery C Vilbert
- Department of Chemistry and Chemical Biology, Baker Laboratory , Cornell University , Ithaca , New York 14853 , United States
| | - Ida M DiMucci
- 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
| | - Kyle M Lancaster
- Department of Chemistry and Chemical Biology, Baker Laboratory , Cornell University , Ithaca , New York 14853 , United States
| | - Pierre Moënne-Loccoz
- Department of Chemical Physiology and Biochemistry , Oregon Health & Science University , Portland , Oregon 97239 , 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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