Bio‐organometallic Approaches to Nitrogen Fixation Chemistry

Peters, Jonas C.; Mehn, Mark P.

doi:10.1002/9783527609352.ch3

Cited by 67 publications

(58 citation statements)

References 98 publications

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“…For example, in the FeMo cofactor of the nitrogenase enzyme, the structure of which features seven iron centres and a single molybdenum centre held together by nine bridging sulphides and a carbide atom (Fig. 7) 12,75 , dinitrogen reduction is proposed to occur at a single iron site 76 . Dinitrogen binds and is heterolytically cleaved at this iron site, which results in the release of ammonia and generation of Fe IV ≡N.…”

Section: Iron-nitrido Complexesmentioning

confidence: 99%

“…Scepaniak et al 90 combined the ligand systems of Vogel et al 87 and Betley and Peters 85 by using the phenyl-tris(1-tert-butylimidazol2ylidene)borate (PhB( t BuIm) 3 − ), a boron-anchored tripodal tris (carbene) ligand system originally introduced by Fränkel et al 89 Photolysis of [(PhB( t BuIm) 3 12,75 , and the proposed intermediates (scheme in the box) of the dinitrogen activation process occurring at a single iron site 76 .…”

Section: Iron-nitrido Model Complexesmentioning

confidence: 99%

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

2012

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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.

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Section: Iron-nitrido Complexesmentioning

confidence: 99%

Section: Iron-nitrido Model Complexesmentioning

confidence: 99%

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

2012

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“…Well-characterized homogeneous complexes derived from iron and N 2 can give fundamental insight into potentially feasible mechanisms, because one can structurally characterize iron sites with partially reduced N 2 , and monitor elementary transformations along the way to ammonia 10. To this end, a growing number of molecular iron-based catalysts for N 2 reduction are emerging 11,12.…”

Section: Introductionmentioning

confidence: 99%

Stepwise N–H bond formation from N₂-derived iron nitride, imide and amide intermediates to ammonia

et al. 2016

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“…We have suggested elsewhere that a similar hemi-labile role may be played by the interstitial light X-atom of the FeMo-cofactor, enabling a high degree of conformational and redox flexibility at a single iron N 2 binding site. 20 In this regard the central X-atom could act like a spring as the iron site coordinates various reduced nitrogenous ligands during turnover. This scenario would allow the iron center to modulate its local geometry by varying its degree of interaction with the light X-atom under crude local three-fold symmetry, possibly sampling trigonal bipyramidal, trigonal pyramidal, and/or pseudotetrahedral geometries as a function of the nature of the state of reduction of the nitrogenous ligand.…”

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N₂ Functionalization at Iron Metallaboratranes

2011

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The reactivity of the anionic dinitrogen complex [(TPB)Fe(N2)]− (2, TPB = tris-[2-(diisopropylphosphino)phenyl]borane) towards silicon electrophiles has been examined. Compound 2 reacts with trimethylsilyl chloride (TMSCl) to yield the silyldiazenido complex (TPB)Fe(NNSiMe3) (3), which is reduced by Na/Hg in THF to yield the corresponding sodium-bound anion [(TPB)Fe(NNSiMe3)]Na(THF) (4). The use of 1,2-bis(chlorodimethylsilyl)ethane in the presence of excess Na/Hg results in the disilylation of the bound N2 molecule to yield the disilylhydrazido(2−) complex (TPB)Fe≡NR (5, R = 2,2,5,5-tetramethyl-1-aza-2,5-disilacyclopentyl). One of the phosphine arms of TPB in 5 can be substituted by CO or tBuNC to yield crystalline adducts (TPB)(L)Fe≡NR (6: L = CO; 7: L = tBuNC). The N-N bond in 7 is cleaved upon standing at room temperature to yield a phosphoraniminato/disilylamido iron(II) complex (8). The flexibility of the Fe–B linkage is thought to play a key role in these transformations of Fe-bound dinitrogen.

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Bio‐organometallic Approaches to Nitrogen Fixation Chemistry

Cited by 67 publications

References 98 publications

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

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

Stepwise N–H bond formation from N₂-derived iron nitride, imide and amide intermediates to ammonia

N₂ Functionalization at Iron Metallaboratranes

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Bio‐organometallic Approaches to Nitrogen Fixation Chemistry

Cited by 67 publications

References 98 publications

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

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

Stepwise N–H bond formation from N2-derived iron nitride, imide and amide intermediates to ammonia

N2 Functionalization at Iron Metallaboratranes

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Stepwise N–H bond formation from N₂-derived iron nitride, imide and amide intermediates to ammonia

N₂ Functionalization at Iron Metallaboratranes