Mn2+/Mn3+ and Mn3+/Mn4+ mixed valence binuclear manganese complexes of biological interest

Dismukes, G. Charles; Sheats, John E.; Smegal, John A.

doi:10.1021/ja00257a057

Cited by 71 publications

(50 citation statements)

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“…However, as has been pointed out in the literature, a much larger spectrum would be expected. [65] Moreover, such a (µ-peroxo)Mn II Mn III species would be expected to be unstable, whereas we found the multi-line signal to persist after the EPR tube had been left at room temperature for 5 min.…”

Section: Reactivity In Anhydrous Dmsomentioning

confidence: 63%

New MnII Complexes with an N/O Coordination Sphere from TripodalN-Centered Ligands − Characterization from Solid State to Solution and Reaction with Superoxide in Non-Aqueous and Aqueous Media

Policar

Durot

Lambert

et al. 2001

Eur. J. Inorg. Chem.

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The crystal structure of a dimeric bis(µ-carboxylato)Mn II Mn II complex (2) with a tetradentate N-centered tripodal ligand, N,N-bis [(1-methylimidazol-2-yl)methyl]glycinate, is presented. The carboxylates are bridging monodentate. This complex shows some striking differences to the previously published parent compound 1 obtained with the closely related ligand N- [(1-methylimidazol-2-yl)methyl]-N-(2-pyridylmethyl)glycinate. The carboxylato bridges in both structures are shown to be disrupted in solution. The reactivities in solution of compounds 1 and 2 toward superoxide were

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Section: Reactivity In Anhydrous Dmsomentioning

confidence: 63%

New MnII Complexes with an N/O Coordination Sphere from TripodalN-Centered Ligands − Characterization from Solid State to Solution and Reaction with Superoxide in Non-Aqueous and Aqueous Media

Policar

Durot

Lambert

et al. 2001

Eur. J. Inorg. Chem.

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“…Dismukes recognized the similarity between the multiline signal observed in the EPR spectrum for these dimers (g = 2, 16 lines) and that of the OEC in the S 2 (g = 2, 19-22 lines) [109][110][111]. Based on the magnitude of the hyperfine coupling constants and energy of the transition, it was concluded that the OEC contained a mixed valence manganese cluster [112].…”

Section: Mn-μ-o 2 -Mnmentioning

confidence: 85%

Reflections on small molecule manganese models that seek to mimic photosynthetic water oxidation chemistry

Mullins

Pecoraro

2008

Coordination Chemistry Reviews

328

252

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Recent advances in the study of the Oxygen Evolving Complex (OEC) of Photosystem II (PSII) include structural information attained from several X-ray crystallographic (XRD) and spectroscopic (XANES and EXAFS) investigations. The possible structural features gleaned from these studies have enabled synthetic chemists to design more accurate model complexes, which in turn, offer better insight into the possible pathways used by PSII to drive photosynthetic water oxidation catalysis. Mononuclear model compounds have been used to advance the knowledge base regarding the physical properties and reactivity of high-valent (Mn(IV) or Mn(V)) complexes. Such investigations have been especially important in regard to the manganyl (Mn(IV)=O or Mn(V)≡O) species, as there are no reports, to date, of any structural characterized multinuclear model compounds that incorporate such a functionality. Dinuclear and trinuclear model compounds have also been thoroughly studied in attempts to draw further comparison to the physical properties observed in the natural system and to design systems of catalytic relevance. As the reactive center of the OEC has been shown to contain an oxo-Mn(4)Ca cluster, exact structural models necessitate a tetranuclear Mn core. The number of models that make use of Mn(4) clusters has risen substantially in recent years, and these models have provided evidence to support and refute certain mechanistic proposals. Further work is needed to adequately address the rationale for Ca (and Cl) in the OEC and to determine the sequence of events that lead to O(2) evolution.

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“…55 Mn hyperfine field than a Mn III /Mn IV pair in the case of a manganese porphyrin. 44 The simulation was done by using the EasySpin software, 45 which solves the following spin Hamiltonian: · = · · + · · − · + · · − H bB g S S A I g b B I S A I g b B I 2 1 1 n n 1 2 2 n n where S is the total electron spin, B is the external magnetic field, A is the intrinsic hyperfine tensor, I is the nuclear spin, g is the g factor, and β is the Bohr magneton, g n is the nuclear g factor, and β n is the nuclear magneton. The subscripts 1 and 2 refer to the two inequivalent manganese ions.…”

Section: ■ Resultsmentioning

confidence: 99%

Reverse Catalase Reaction: Dioxygen Activation via Two-Electron Transfer from Hydroxide to Dioxygen Mediated By a Manganese(III) Salen Complex

Kurahashi

2015

Inorg. Chem.

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Although atmospheric dioxygen is regarded as the most ideal oxidant, O2 activation for use in oxygenation reactions intrinsically requires a costly sacrificial reductant. The present study investigated the use of aqueous alkaline solution for O2 activation. A manganese(III) salen complex, Mn(III)(salen)(Cl), in toluene reacts with aqueous KOH solution under aerobic conditions, which yields a di-μ-oxo dimanganese(IV) salen complex, [Mn(IV)(salen)]2(μ-O)2. The (18)O isotope experiments show that (18)O2 is indeed activated to give [Mn(IV)(salen)]2(μ-(18)O)2 via a peroxide intermediate. Interestingly, the (18)OH(-) ion in H2(18)O was also incorporated to yield [Mn(IV)(salen)]2(μ-(18)O)2, which implies that a peroxide species is also generated from (18)OH(-). The addition of benzyl alcohol as a stoichiometric reductant selectively inhibits the (18)O incorporation from (18)OH(-), indicating that the reaction of Mn(III)(salen)(Cl) with OH(-) supplies the electrons for O2 reduction. The conversion of both O2 and OH(-) to a peroxide species is exactly the reverse of a catalase-like reaction, which has a great potential as the most efficient O2 activation. Mechanistic investigations revealed that the reaction of Mn(III)(salen)(Cl) with OH(-) generates a transient species with strong reducing ability, which effects the reduction of O2 by means of a manganese(II) intermediate.

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Mn2+/Mn3+ and Mn3+/Mn4+ mixed valence binuclear manganese complexes of biological interest

Cited by 71 publications

References 0 publications

New MnII Complexes with an N/O Coordination Sphere from TripodalN-Centered Ligands − Characterization from Solid State to Solution and Reaction with Superoxide in Non-Aqueous and Aqueous Media

New MnII Complexes with an N/O Coordination Sphere from TripodalN-Centered Ligands − Characterization from Solid State to Solution and Reaction with Superoxide in Non-Aqueous and Aqueous Media

Reflections on small molecule manganese models that seek to mimic photosynthetic water oxidation chemistry

Reverse Catalase Reaction: Dioxygen Activation via Two-Electron Transfer from Hydroxide to Dioxygen Mediated By a Manganese(III) Salen Complex

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