Diammine{N-[2-(hydroxyimino)propionyl]-N′-[2-(oxidoimino)propionyl]propane-1,3-diaminido-κ4N,N′,N′′,N′′′}iron(III)

Tomyn, Stefania; Haukka, Matti; Nedelkov, Ruslan V.

doi:10.1107/s160053681204826x

Cited by 4 publications

(2 citation statements)

References 14 publications

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“…Each new complex was unambiguously identified by single crystal X-ray diffraction (XRD) studies, with the solid-state structures shown in Figure a. The observed Fe–N amine bond distances of 2.017(4), 2.037(6), and 2.087(5) Å for 1-(NH 3 ) 2 , 1-(MeNH 2 ) 2 , and 1-(Me 2 NH) 2 , respectively, are consistent with increasing amine bulk and similar to previous reports. − Pc ring distortions are most pronounced for 1-(MeNH 2 ) 2 and may be due to packing effects observed in the extended structure . The zero-field 57 Fe Mössbauer spectra of each complex were collected at 90 K and revealed very similar quadrupole doublets with isomer shift and quadrupole splitting (δ, |Δ E Q | (mm/s)) values of: 1-(NH 3 ) 2 (0.29, 1.14 ), 1-(MeNH 2 ) 2 (0.24, 0.87 ), and 1-(Me 2 NH) 2 (0.25, 0.99 ) (Figure b).…”

Section: Results and Discussionsupporting

confidence: 88%

Multiple N–H and C–H Hydrogen Atom Abstractions Through Coordination-Induced Bond Weakening at Fe-Amine Complexes

2021

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We report the use of the reported Fe-phthalocyanine complex, PcFe (1; Pc = 1,4,8,11,15,18,22,25-octaethoxy-phthalocyanine), to generate PcFe–amine complexes 1-(NH 3 ) 2 , 1-(MeNH 2 ) 2 , and 1-(Me 2 NH) 2 . Treatment of 1 or 1-(NH 3 ) 2 to an excess of the stable aryloxide radical, 2,4,6-tritert-butylphenoxyl radical ( tBuArO•), under NH3 resulted in catalytic H atom abstraction (HAA) and C–N coupling to generate the product 4-amino-2,4,6-tritert-butylcyclohexa-2,5-dien-1-one (2) and tBuArOH. Exposing 1-(NH 3 ) 2 to an excess of the trityl (CPh3) variant, 2,6-di-tert-butyl-4-tritylphenoxyl radical (TrArO•), under NH3 did not lead to catalytic ammonia oxidation as previously reported in a related Ru-porphyrin complex. However, pronounced coordination-induced bond weakening of both α N–H and β C–H in the alkylamine congeners, 1-(MeNH 2 ) 2 and 1-(Me 2 NH) 2 , led to multiple HAA events yielding the unsaturated cyanide complex, 1-(MeNH 2 )(CN), and imine complex, 1-(MeNCH 2 ) 2 , respectively. Subsequent C–N bond formation was also observed in the latter upon addition of a coordinating ligand. Detailed computational studies support an alternating mechanism involving sequential N–H and C–H HAA to generate these unsaturated products.

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Section: Results and Discussionsupporting

confidence: 88%

Multiple N–H and C–H Hydrogen Atom Abstractions Through Coordination-Induced Bond Weakening at Fe-Amine Complexes

2021

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“…The coordination of ammonia by 6 is in contrast to the behavior of the iron(II) amide Fe{N(SiMe 3 ) 2 } 2 , which yielded only intractable solids during attempts to study its reactivity with ammonia. Complex 6 is a rare example of a species in which iron coordinates more than one ammine ligand; only three other examples of monomeric iron complexes coordinating two or more ammine ligands have been identified crystallographically. − Unlike the spectra of complexes 4 and 5 , the 1 H NMR spectrum of 6 clearly shows the presence of a monomeric diaryloxide species in solution, with no evidence of the presence of dimeric 1 . The spectrum of 6 contains a single set of paramagnetically shifted signals attributable to the protons of the substituted aryl group, rather than the pairs of signals attributable to the bridging and terminal ligands present in the spectra of dimers 1 and 2 .…”

Section: Resultsmentioning

confidence: 99%

Low-Coordinate Iron Chalcogenolates and Their Complexes with Diethyl Ether and Ammonia

2021

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Treatment of Fe{N(SiMe3)2}2 with 2 equiv of the appropriate phenol or thiol affords the dimers {Fe(OC6H2-2,6-Bu t 2-4-Me)2}2 (1) and {Fe(OC6H3-2,6-Bu t 2)2}2 (2) or the monomeric Fe{SC6H3-2,6-(C6H3-2,6-Pr i 2)2}2 (3) in moderate to excellent yields. Recrystallization of 1 and 2 from diethyl ether gives the corresponding three-coordinate ether complexes Fe(OC6H3-2,6-Bu t 2-4-Me)2(OEt2) (4) and Fe(OC6H3-2,6-Bu t 2)2(OEt2) (5). In contrast, no diethyl ether complex is formed by the dithiolate 3. The 1H NMR spectra of 4 and 5 show equilibria between the ether complexes and the base-free dimers. A comparison of these spectra with those of the dimeric 1 and 2 allows an unambiguous assignment of the paramagnetically shifted signals. Treatment of 1 with excess ammonia gives the tetrahedral diammine Fe(OC6H2-2,6-Bu t 2-4-Me)2(NH3)2 (6). Ammonia is strongly coordinated in 6, with no apparent loss of ammine ligand either in solution or upon heating under low pressure. In contrast, significantly weaker ammonia coordination is observed when dithiolate 3 is treated with excess ammonia, which gives the diammine Fe{SC6H3-2,6-(2,6-Pr i 2-C6H3)2}2(NH3)2 (7). Complex 7 readily loses ammonia either in solution or under reduced pressure to give the monoammine complex Fe{SC6H3-2,6-(2,6-Pr i 2-C6H3)2}2(NH3) (8). The weak binding of ammonia by iron thiolate 7 reflects the likely behavior of the proposed iron–sulfur active site in nitrogenases, where release of ammonia is required to close the catalytic cycle.

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Oxidation of Ammonia Catalyzed by a Molecular Iron Complex: Translating Chemical Catalysis to Mediated Electrocatalysis

Liu,

Johnson,

Appel

et al. 2024

Angewandte Chemie

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Ammonia is a promising candidate in the quest for sustainable, clean energy. With its capacity to serve as an energy carrier, the oxidation of ammonia opens avenues for carbon‐neutral approaches to address worldwide growing energy needs. We report the catalytic chemical oxidation of ammonia by an Earth‐abundant transition metal complex, trans‐[LFeII(MeCN)2][PF6]2, where L is a macrocyclic ligand bearing four N‐heterocyclic carbene (NHC) donors. Using triarylaminium radical cations in MeCN, up to 182 turnovers of N2 per Fe were obtained from chemical catalysis with an extremely low loading of the Fe catalyst (0.043 mM, 0.004 mol % catalyst). This chemical catalysis was successfully transitioned to mediated electrocatalysis for the oxidation of ammonia. Molecular electrocatalysis by the Fe catalyst and the mediator (p‐MeOC6H4)3N exhibited a catalytic half‐wave potential (Ecat/2) of 0.18 V vs [Cp2Fe]+/0 in MeCN, and achieved 9.3 turnovers of N2 at an applied potential of 0.20 V vs [Cp2Fe]+/0 at −20 °C in controlled‐potential electrolysis, with a Faradaic efficiency of 75%. Based on computational results, the catalyst undergoes sequential oxidation and deprotonation steps to form [LFeIV(NH2)2]2+, and thereafter bimetallic coupling to form an N−N bond.

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Diammine{N-[2-(hydroxyimino)propionyl]-N′-[2-(oxidoimino)propionyl]propane-1,3-diaminido-κ⁴N,N′,N′′,N′′′}iron(III)

Cited by 4 publications

References 14 publications

Multiple N–H and C–H Hydrogen Atom Abstractions Through Coordination-Induced Bond Weakening at Fe-Amine Complexes

Multiple N–H and C–H Hydrogen Atom Abstractions Through Coordination-Induced Bond Weakening at Fe-Amine Complexes

Low-Coordinate Iron Chalcogenolates and Their Complexes with Diethyl Ether and Ammonia

Oxidation of Ammonia Catalyzed by a Molecular Iron Complex: Translating Chemical Catalysis to Mediated Electrocatalysis

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