Synthesis and Mössbauer Characterization of Octahedral Iron(II) Carbonyl Complexes FeI2(CO)3L and FeI2(CO)2L2: Developing Models of the [Fe]-H2ase Active Site

Li, Bin; Liu, Tianbiao; Popescu, Codrina V.; Bilko, Andrey; Darensbourg, Marcetta Y.

doi:10.1021/ic9017882

Cited by 76 publications

(64 citation statements)

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“…While this CO adduct was not isolated, the n(CO) bands at 2102(w) and 2046(vs) cm À1 are, in position and pattern, nearly identical to that of the well-characterized mer-[Fe(CO) 3 Figure S5). [21] Notably, the n(CO) IR band patterns of the facial isomers within this series are distinctly different from that of the meridional. [22] Hence we propose a tricarbonyl species, mer-[(H-NS)Fe(CO) 3 …”

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confidence: 84%

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Analysis of a Pentacoordinate Iron Dicarbonyl as Synthetic Analogue of the Hmd or Mono‐Iron Hydrogenase Active Site

Liu

Popescu

et al. 2010

Chemistry A European J

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Pentacoordinate iron dicarbonyls, (NS)Fe(CO)(2)P (NS=2-amidothiophenylate, P=PCy(3) (4), PPh(3), (5), and P(OEt)(3) (6)) were prepared as potential biomimetics of the active site of the mono-iron hydrogenase, [Fe]-H(2)ase. Full characterization including X-ray diffraction, density functional theory (DFT) computations, and Mössbauer studies for complexes 5 and 6 find that, despite similar infrared v(CO) pattern and absorption frequencies as the active site of the [Fe]-H(2)ase, the geometrical distortions towards trigonal bipyramidal, the negative isomer shift parameters, and the differences in CO-uptake reactivity are due to the "non-innocence" of the NS ligand. Ligand-based protonation with a strong acid, HBF(4).Et(2)O, interrupted the extensive pi-delocalization over Fe and NS ligand of complex 4 and switched on CO uptake (1 bar) to form a CO adduct, mer-[(H-NS)Fe(CO)(3)(PCy(3))](+) or 4(CO)-H(+). The extrinsic CO is reversibly removed on deprotonation with Et(3)N to regenerate complex 4. In a (13)CO atmosphere, concomitant CO uptake by 4-H(+) and exchange with intrinsic CO groups provide a facile route to (13)C-labeled 4(CO)-H(+) and, upon deprotonation, (13)C-labeled complex 4. DFT calculations show substantial Fe character in the LUMO of 4-H(+) typical of the d(6) Fe(II) in a regular square-pyramidal geometry. Thus, the Lewis acidity of 4-H(+) makes it amenable for CO binding, whereas the dianionic NS ligand renders the iron center of 4 insufficiently electrophilic and largely of Fe(I) character.

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confidence: 84%

“…Neither did complex 4 show reactivity with other Lewis bases such as À0.0104(6) 1.00(1) 7 [21] 0.065 0.70 [20] 0.076…”

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confidence: 99%

Analysis of a Pentacoordinate Iron Dicarbonyl as Synthetic Analogue of the Hmd or Mono‐Iron Hydrogenase Active Site

Liu

Popescu

et al. 2010

Chemistry A European J

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“…[4,[27][28]71]. Some selected examples are shown in Figure 2, and several of them have very similar structure with the [Fe]-hydrogenase [72][73][74][75][76][77][78][79]. However, until now, none of the [Fe]-hydrogenase models can activate H 2 , even those structurally very similar to the enzyme.…”

Section: Bio-inspired Complexes With An Internal Amine Moietymentioning

confidence: 99%

Hydrogen-activating models of hydrogenases

Chen

2015

Coordination Chemistry Reviews

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“…Such iron complexes (especially mononuclear species) can be challenging to isolate, requiring low temperatures and dark conditions. [10][11][12][13][14][15] In contrast, the Mn(I) carbonyls are thermally stable under ambient conditions in non-coordinating solvents, and exhibit a reduced sensitivity to light. Therefore, as an entry point to iron chemistry, we wished to explore the coordination of a tridentate NNS ligand frame with manganese carbonyls.…”

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confidence: 99%

Tuning coordination modes of pyridine/thioether Schiff base (NNS) ligands to mononuclear manganese carbonyls

et al. 2014

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We have investigated the coordination modes of NNS Schiff base, thioether ligands to manganese (I) carbonyls. The ligands contain ortho substituted pyridines (H, CH 3 , OCH 3 , fluorophenyl) and varying substituents (H, CH 3 ) at the Schiff base linkage. In general, reaction of [Mn(CO) 5 Br] with a tridentate NNS ligand in CH 2 Cl 2 affords species in which the thioether-S may be bound or unbound to the manganese center, depending on the steric and electronic substitution in the ligand framework; as a result, the complexes exhibit two or three carbonyl ligands, respectively. Aldehyde-derived ligand frames ( tricarbonyl motif. We highlight that coordination of these NNS ligands to Mn(I) carbonyls occurs on a soft conformational landscape, and that ligand substituents can be rationally employed to favor the desired coordination mode.

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Synthesis and Mössbauer Characterization of Octahedral Iron(II) Carbonyl Complexes FeI₂(CO)₃L and FeI₂(CO)₂L₂: Developing Models of the [Fe]-H₂ase Active Site

Cited by 76 publications

References 32 publications

Analysis of a Pentacoordinate Iron Dicarbonyl as Synthetic Analogue of the Hmd or Mono‐Iron Hydrogenase Active Site

Analysis of a Pentacoordinate Iron Dicarbonyl as Synthetic Analogue of the Hmd or Mono‐Iron Hydrogenase Active Site

Hydrogen-activating models of hydrogenases

Tuning coordination modes of pyridine/thioether Schiff base (NNS) ligands to mononuclear manganese carbonyls

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