Observation of Fe(V)=O using variable-temperature mass spectrometry and its enzyme-like C–H and C=C oxidation reactions

Prat, Irene; Mathieson, Jennifer S.; Güell, Mireia; Ribas, Xavi; Luis, Josep M.; Cronin, Leroy; Costas, Miguel

doi:10.1038/nchem.1132

Cited by 273 publications

(229 citation statements)

References 37 publications

Supporting

Mentioning

215

Contrasting

Unclassified

Order By: Relevance

Section: Introductionmentioning

confidence: 99%

“…1 Among this diverse group, metal oxides stand out because of their widespread presence in biological and bio-inspired processes and for applications utilizing their unique magnetic, electronic, and thermal properties. [2][3][4][5][6][7][8][9][10][11][12][13] Developing a clear understanding of how M-O electronic structure and orbital mixing changes for a range of metal oxo compounds and materials will greatly benefit attempts to advance these technologies.Among approaches explored previously, ligand K-edge X-ray absorption spectroscopy (XAS) has emerged as an effective method for quantitatively probing electronic structure and orbital mixing in metal-chlorine and metal-sulfur bonds. 14 This spectroscopic technique probes bound state transitions between core ligand 1s orbitals and unoccupied molecular orbitals.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Covalency in Metal–Oxygen Multiple Bonds Evaluated Using Oxygen K-edge Spectroscopy and Electronic Structure Theory

et al. 2013

View full text Add to dashboard Cite

X-ray absorption spectroscopy using fluorescence and transmission (via a scanning transmission X-ray microscope), and linear-response density functional theory. The results suggest that moving from Group 6 to Group 7 or down the triads increases M-O e* (π*) mixing. Meanwhile, t 2 * mixing (σ* + π*) remains relatively constant within the same Group. These unexpected changes in frontier orbital energy and composition are evaluated in terms of periodic trends in d orbital energy and radial extension. 3Introduction.The nature of chemical bonds between metals and light atoms such as oxygen, nitrogen, and carbon is of widespread interest because these interactions control the physics and chemistry of many technologically important processes and compounds. Light atoms are prone to form highly covalent metalligand multiple bonds involving one σ bond and one or more π bonds, resulting in oxo, imido, nitrido, alkylidene, alkylidyne, and carbido functionalities with many desirable chemical reactivities and physical properties. 1 Among this diverse group, metal oxides stand out because of their widespread presence in biological and bio-inspired processes and for applications utilizing their unique magnetic, electronic, and thermal properties. [2][3][4][5][6][7][8][9][10][11][12][13] Developing a clear understanding of how M-O electronic structure and orbital mixing changes for a range of metal oxo compounds and materials will greatly benefit attempts to advance these technologies.Among approaches explored previously, ligand K-edge X-ray absorption spectroscopy (XAS) has emerged as an effective method for quantitatively probing electronic structure and orbital mixing in metal-chlorine and metal-sulfur bonds. 14 This spectroscopic technique probes bound state transitions between core ligand 1s orbitals and unoccupied molecular orbitals. The excitations can only have transition intensity if the empty acceptor orbitals contain ligand p character. 14 At first glance, such an approach seems well-suited for studying metal-oxygen bonding. However, attempts to use this technique to study non-conducting molecular systems are complicated by experimental barriers derived from the low energy of the oxygen K-edge (ca. 530 eV), which magnifies issues associated with surface contamination, saturation, and self-absorption effects.In this manuscript, we overcome these challenges and evaluate relative changes in metal-oxo electronic structure and orbital mixing for non-conducting molecular solids using O K-edge spectroscopy in conjunction with hybrid density functional theory (DFT) calculations. Specifically, non-resonant inelastic X-ray scattering (NIXS), XAS, and linear-response density functional theory (TDDFT) are used as Density functional theory calculations using relativistic effective core potentials (RECPs) were conducted to determine how antibonding molecular orbital compositions and energies varied as (1) metals 5 changed within a group (Cr, Mo, W and Mn, Tc, Re) and (2) metal charges increased from M 6+ (Group 6) to M 7+ (Group 7)...

show abstract

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

Covalency in Metal–Oxygen Multiple Bonds Evaluated Using Oxygen K-edge Spectroscopy and Electronic Structure Theory

et al. 2013

View full text Add to dashboard Cite

show abstract

“…However, the spectroscopically characterized [(TAML)Fe V (O)] − anion, which is the only known isolable oxoiron(V) species in the literature, was found to be a sluggish oxidant 32 38 . Therefore, the involvement of Fe V (O)(OH) intermediates in oxygenation reactions remained doubtful until very recently 39 . Using variabletemperature mass spectrometry, Prat et al 39 provided evidence for such a reactive intermediate in a synthetic system.…”

mentioning

confidence: 99%

“…Therefore, the involvement of Fe V (O)(OH) intermediates in oxygenation reactions remained doubtful until very recently 39 . Using variabletemperature mass spectrometry, Prat et al 39 provided evidence for such a reactive intermediate in a synthetic system.…”

mentioning

confidence: 99%

The biology and chemistry of high-valent iron–oxo and iron–nitrido complexes

2012

View full text Add to dashboard Cite

selective functionalization of unactivated c-H bonds and ammonia production are extremely important industrial processes. a range of metalloenyzmes achieve these challenging tasks in biology by activating dioxygen and dinitrogen using cheap and abundant transition metals, such as iron, copper and manganese. High-valent iron-oxo and -nitrido complexes act as active intermediates in many of these processes. the generation of well-described model compounds can provide vital insights into the mechanism of such enzymatic reactions. advances in the chemistry of model high-valent iron-oxo and -nitrido systems can be related to our understanding of the biological systems.H igh-valent oxoiron(IV) and formally oxoiron(V) species have been spectroscopically identified as active intermediates in the catalytic cycles of a number of enzymatic systems 1-10 . Haem and non-haem proteins use these reactive intermediates to couple the activation of dioxygen to the oxidation of their substrates. In most cases, an oxygen atom is inserted into an unactivated C-H bond of the substrate; for example, in hydroxylation reactions [1][2][3][4][5][6][7][8][9][10] . However, many other reactions, including halogenation, desaturation, cyclization, epoxidation and decarboxylation, are also known to involve oxoiron species 1,3 . Superoxidized iron complexes with (valence) isoelectronic imido and nitrido ligands, as well as 'surface nitrides' , have also been implicated as key intermediates in the nitrogen atom transfer reactions 11 , the biological synthesis of ammonia by the nitrogenase enzyme 12-16 and the industrial Haber-Bosch process 17 .The generation of well-described model compounds can provide vital insights into the mechanism of such enzymatic reactions. Consequently, considerable effort has been made by synthetic chemists to prepare viable models for the putative reaction intermediates in the catalytic cycles of O 2 and N 2 activating enzymes. In this review, we provide an overview of all high-valent oxoiron and nitridoiron species that have been either identified or proposed as reactive intermediates in biology. Subsequently, we summarize some of the recent advances in bioinorganic chemistry that have led to the identification and isolation of iron complexes in unusually high formal oxidation states, containing iron-oxygen or iron-nitrogen multiple bonds. The spectroscopic characterization and the reactivity studies of these model complexes provide vital insights into the mechanism that nature uses to induce the reductive cleavage of dioxygen or dinitrogen in carrying out a number of important biochemical oxidative transformations. Moreover, the comparative review of the electronic structures of the isoelectronic oxoiron and nitridoiron functionalities reveals that the Fe-N bonds are intrinsically more covalent than the Fe-O bonds.

show abstract

“…In competitive contribution, Costas and co-workers showed that the introduction of additional steric crowd at the pyridine moieties, as well as manipulating with the symmetry of the chiral ligand can divert the oxidation selectivity from 3° C(sp 3 )-H bonds to stronger 2° C(sp 3 )-H bonds, which is critical for the selective oxygenation of complex molecules such as natural products [35][36][37][38]. The mechanism of non-heme iron catalyzed oxidations has been extensively studied experimentally [39]; it has now been accepted that the C-H oxidation proceeds via the classical rebound mechanism [40] (Figure 1), with participation of the elusive oxoperferryl species [41][42][43][44][45][46][47][48][49]. In contrast to non-heme Fe complexes, the catalytic activity (as well as the mechanism of catalytic action) of structurally related Mn complexes have so far been much less studied.…”

Section: Introductionmentioning

confidence: 99%

Direct Selective Oxidative Functionalization of C–H Bonds with H2O2: Mn-Aminopyridine Complexes Challenge the Dominance of Non-Heme Fe Catalysts

2016

View full text Add to dashboard Cite

Non-heme iron(II) complexes are widespread synthetic enzyme models, capable of conducting selective C-H oxidation with H 2 O 2 in the presence of carboxylic acid additives. In the last years, structurally similar manganese(II) complexes have been shown to catalyze C-H oxidation with similarly high selectivity, and with much higher efficiency. In this mini-review, recent catalytic and mechanistic data on the selective C-H oxygenations with H 2 O 2 in the presence of manganese complexes are overviewed. A distinctive feature of catalyst systems of the type Mn complex/H 2 O 2 /carboxylic is the existence of two alternative reaction pathways (as found for the oxidation of cumenes), one leading to the formation of alcohol, and the other to ester. The mechanisms of formation of the alcohol and the ester are briefly discussed.

show abstract

Observation of Fe(V)=O using variable-temperature mass spectrometry and its enzyme-like C–H and C=C oxidation reactions

Cited by 273 publications

References 37 publications

Covalency in Metal–Oxygen Multiple Bonds Evaluated Using Oxygen K-edge Spectroscopy and Electronic Structure Theory

Covalency in Metal–Oxygen Multiple Bonds Evaluated Using Oxygen K-edge Spectroscopy and Electronic Structure Theory

The biology and chemistry of high-valent iron–oxo and iron–nitrido complexes

Direct Selective Oxidative Functionalization of C–H Bonds with H2O2: Mn-Aminopyridine Complexes Challenge the Dominance of Non-Heme Fe Catalysts

Contact Info

Product

Resources

About