Preparation and magnetism of the binuclear iron(II) complexes [{Fe(C9H21N3)X2}2](X = NCS, NCO, or N3) and their reaction with NO. Crystal structures of [{Fe(C9H21N3)(NCS)2}2] and [Fe(C9H21N3)(NO)(N3)2]

Pohl, Klaus; Wieghardt, Karl; Nuber, Bernhard; Weiß, Johannes

doi:10.1039/dt9870000187

Cited by 65 publications

(72 citation statements)

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“…I is a {FeOO} 8 complex, and computational studies from the Solomon group suggest that it should be described as a Fe III ‐superoxo species 43. These calculations were calibrated by correlating experimental and computational data for the related {FeNO} 7 complexes,43 which have been prepared by addition of NO to the Fe II forms of a number of different mononuclear non‐heme enzymes44,45 and models thereof 46,47. The postulated Fe III ‐superoxo complex I is proposed to react by a nucleophilic attack of the uncoordinated O atom on C2 of αKG, thereby forming the bicyclic species, II .…”

Section: Mechanismmentioning

confidence: 99%

Mechanism of Taurine: α‐Ketoglutarate Dioxygenase (TauD) from Escherichia coli

et al. 2005

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The iron(II)-and α-ketoglutarate-dependent dioxygenases comprise enzymes that catalyze a variety of important reactions in biology, including steps in the biosynthesis of collagen and antibiotics, the degradation of xenobiotics, the repair of alkylated DNA, and the sensing of oxygen and response to hypoxia. In these reactions, the reductive activation of oxygen is coupled to hydroxylation of the substrate and decarboxylation of the co-substrate, α-ketoglutarate. It is believed that a single, conserved mechanistic pathway for formation of a high-valent iron intermediate that attacks the substrate is operant in all members of this family. Application 4245 of a combination of rapid kinetic and spectroscopic techniques to the reaction of taurine/α-ketoglutarate dioxygenase (TauD), one member of this large enzyme family, has led to the detection of two reaction intermediates. The first intermediate, which is termed J, is a high-spin Fe IV -oxo complex. Decay of J exhibits a large, normal C1 deuterium kinetic isotope effect, demonstrating that it is the species activating the C-H bond for hydroxylation. The second intermediate is an Fe II -containing product(s) complex.

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Section: Mechanismmentioning

confidence: 99%

Mechanism of Taurine: α‐Ketoglutarate Dioxygenase (TauD) from Escherichia coli

et al. 2005

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“…[41][42][43][44][45] Among them, mononuclear or dinuclear complexes based on thioether ligands, with FeN 4 S 2 coordination sphere, have been shown to exhibit original transitions such as multi-step cooperative SCO behaviour. [41][42][43][44] Concerning Fe(II) complexes with FeN 5 S coordination sphere, very few examples have been investigated, [45][46][47][48][49] and to the best of our knowledge, only one example, [{Fe(tpc-OH)(NCS)(μ-NCS)} 2 ](PrOH) 2 (2), exhibits a SCO behaviour. 45 The latter is a dinuclear SCO Fe(II) complex based on the tripodal ligand tris(2-pyridyl)methanol (see scheme 1, R = H) for which the Fe(II) ions are connected by a pair of end-to-end thiocyanato bridges (-N:S-SCN coordination mode) in a head-to-tail configuration.…”

Section: ■Introductionmentioning

confidence: 99%

One-Dimensional Thiocyanato-Bridged Fe(II) Spin Crossover Cooperative Polymer With Unusual FeN₅S Coordination Sphere

et al. 2018

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We present here a novel example of spin crossover phenomenon on a Fe(II) one-dimensional chain with unusual NS coordination sphere. The [{Fe(tpc-OMe)(NCS)(μ-NCS)} ] (1) compound was prepared using the tridentate tpc-OMe ligand (tpc-OMe = tris(2-pyridyl)methoxymethane), FeCl·4HO, and the KSCN salt. Crystallographic investigations revealed that the Fe(II) ions are connected by a single bridging NCS ligand (μ-κN:κS-SCN coordination mode) to afford a zigzag neutral chain running along the [010] direction, in which the thiocyanato bridging groups adopt a cis head-to-tail configuration. The (NS) metal environment arises from one thiocyanato-κS and two thiocyanato-κN ligands and from three pyridine of the fac-tpc-OMe tripodal ligand. This compound presents a unique extension of Fe(II) binuclear complexes into linear chains built on similar tripodal ligands and bridging thiocyanate anions. Compound 1 shows a spin crossover (SCO) behavior which has been evidenced by magnetic, calorimetric, and structural investigations, revealing a sharp cooperative spin transition with a transition temperature of ca. 199 K. Temperature scan rate studies revealed a very narrow hysteresis loop (∼1 K wide). Photoswitching of this compound was also performed, evidencing a very fast relaxation process at low temperature. Among other factors, the linearity of the N-bound terminal thiocyanato ligand appears as the main structural characteristic at the origin of the presence of the SCO transition in compound 1 and in the two others Fe(II) previous systems involving thiocyanato-bridges and tripodal tris(2-pyridyl)methane ligands.

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“…[12] The electrochemical reduction of high-spin non-heme {FeNO} 7 species has been reported for only a few complexes. [12][13][14][15] Importantly, the cyclic voltammograms of these complexes show quasi-reversible or irreversible {FeNO} 7/8 redox couples, which suggests that the reduced species is highly unstable and hence cannot be isolated for further studies. In contrast, the cyclic voltammogram of 1 exhibits a nearly reversible redox event assigned to the {FeNO} 7/8 couple at À1.34 V versus Fc/Fc + (Figure 4).…”

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confidence: 99%

Characterization of a High‐Spin Non‐Heme {FeNO}⁸ Complex: Implications for the Reactivity of Iron Nitroxyl Species in Biology

Speelman

Lehnert

2013

Angew Chem Int Ed

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Stable but able: Chemical and electrochemical reduction of a five-coordinate high-spin non-heme {FeNO}(7) complex (see structure: N blue, Fe orange, and O red) generated the first stable high-spin (S=1) non-heme {FeNO}(8) model complex. The finding that the reduction is metal-centered and causes a decrease in FeNO covalency indicates that in biological systems, reduction activates stable non-heme FeNO units for further transformations.

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Preparation and magnetism of the binuclear iron(II) complexes [{Fe(C9H21N3)X2}2](X = NCS, NCO, or N3) and their reaction with NO. Crystal structures of [{Fe(C9H21N3)(NCS)2}2] and [Fe(C9H21N3)(NO)(N3)2]

Cited by 65 publications

References 1 publication

Mechanism of Taurine: α‐Ketoglutarate Dioxygenase (TauD) from Escherichia coli

Mechanism of Taurine: α‐Ketoglutarate Dioxygenase (TauD) from Escherichia coli

One-Dimensional Thiocyanato-Bridged Fe(II) Spin Crossover Cooperative Polymer With Unusual FeN₅S Coordination Sphere

Characterization of a High‐Spin Non‐Heme {FeNO}⁸ Complex: Implications for the Reactivity of Iron Nitroxyl Species in Biology

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Preparation and magnetism of the binuclear iron(II) complexes [{Fe(C9H21N3)X2}2](X = NCS, NCO, or N3) and their reaction with NO. Crystal structures of [{Fe(C9H21N3)(NCS)2}2] and [Fe(C9H21N3)(NO)(N3)2]

Cited by 65 publications

References 1 publication

Mechanism of Taurine: α‐Ketoglutarate Dioxygenase (TauD) from Escherichia coli

Mechanism of Taurine: α‐Ketoglutarate Dioxygenase (TauD) from Escherichia coli

One-Dimensional Thiocyanato-Bridged Fe(II) Spin Crossover Cooperative Polymer With Unusual FeN5S Coordination Sphere

Characterization of a High‐Spin Non‐Heme {FeNO}8 Complex: Implications for the Reactivity of Iron Nitroxyl Species in Biology

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One-Dimensional Thiocyanato-Bridged Fe(II) Spin Crossover Cooperative Polymer With Unusual FeN₅S Coordination Sphere

Characterization of a High‐Spin Non‐Heme {FeNO}⁸ Complex: Implications for the Reactivity of Iron Nitroxyl Species in Biology