Structural and Spectroscopic Characterization of an Electrophilic Iron Nitrido Complex

Scepaniak, Jeremiah J.; Fulton, Meita D.; Bontchev, Ranko P.; Duesler, Eileen N.; Kirk, Martin L.; Smith, Jeremy M.

doi:10.1021/ja8027372

Cited by 208 publications

(222 citation statements)

References 40 publications

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“…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%

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 Model Complexesmentioning

confidence: 99%

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

2012

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“…[1,2,41] Despite all these available routes, the most common approach to preparing metal nitrides is by photolysis and/or thermolysis of azide complexes, leading to dinitrogen evolution with concomitant two-electron oxidation of the metal center [Reaction (10), Scheme 1]. [2,3,5] It is by the latter route that putative and isolable uranium nitride species [14b] as well as a host of examples of reactive group 8 [6,12,[42][43][44] and 9 [15,16,45] nitride complexes can be prepared. Given the importance of such a general synthetic method for nitride formation, as well as the broad interest in the reactivity of metal nitrides, we were surprised to find that the mechanism for conversion of metal azides to the corresponding nitrides had been rarely investigated according to the literature.…”

Section: Introductionmentioning

confidence: 99%

Formation and Reactivity of the Terminal Vanadium Nitride Functionality

et al. 2013

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The transformation of vanadium(III) azides, [(nacnac)-, Ar = 2,6-(CHMe 2 ) 2 C 6 H 3 ; X = Ntol 2 -, where tol = 4-MeC 6 H 4 , n = 1; X = ArO -, n = 2}, to their corresponding vanadium(V) nitrides, [(nacnac)-VϵN(X)], was investigated through an isotopic labeling crossover experiment. The nuclearity of the azide species is dependent on the size of the supporting ligand, X, with X = ArO -, thus featuring a V 2 N 6 core with two μ 2 -1,3-N 3 bridging ligands across the V III centers. SQUID magnetization studies and multifrequency, high-field EPR (HFEPR) experiments reveal the mononuclear azide complex to be consistent with

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“…[6,7] Reaction of the iron chloride complex [PhB-(MesIm) 3 FeCl] [13] with excess NaN 3 yields the crystallographically characterized azido complex [PhB(MesIm) 3 FeÀN=N= N] (n N=N=N = 2078 cm À1 ), which is then photolyzed to form 1 in high yield. The X-ray crystal structure of 1 shows similar structural features to our related [PhB(tBuIm) 3 Fe N] complex (Scheme 2, inset).…”

mentioning

confidence: 99%

“…The X-ray crystal structure of 1 shows similar structural features to our related [PhB(tBuIm) 3 Fe N] complex (Scheme 2, inset). [7] Thus, the FeÀN (1.499 (5) ) and FeÀ C bond lengths (1.885 (6) Scheme 2. Synthesis of [PhB(MesIm) 3 FeN] (1; Mes = 2,4,6-trimethylphenyl).…”

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confidence: 99%

Formation of Ammonia from an Iron Nitrido Complex

et al. 2009

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Radical ideas: Reaction of the iron(IV) nitrido complex [PhB(MesIm)(3)Fe[triple chemical bond]N] (see picture, Mes=2,4,6-Me(3)C(6)H(2)) with TEMPO-H (1-hydroxy-2,2,6,6-tetramethylpiperidine) results in high yields of ammonia and quantitative formation of [PhB(MesIm)(3)Fe(tempo)]. The mechanism likely involves hydrogen-atom transfer from TEMPO-H to the nitrido complex. Similar reaction with the triphenylmethyl radical yields [PhB(MesIm)(3)Fe[triple chemical bond]N--CPh(3)].

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Structural and Spectroscopic Characterization of an Electrophilic Iron Nitrido Complex

Cited by 208 publications

References 40 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

Formation and Reactivity of the Terminal Vanadium Nitride Functionality

Formation of Ammonia from an Iron Nitrido Complex

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