High-valent bis(oxo)-bridged dinuclear manganese oxamates: Synthesis, crystal structures, magnetic properties, and electronic structure calculations of bis(μ-oxo)dimanganese(IV) complexes with a binucleating o-phenylenedioxamate ligand

Ruiz-Garcı́a, Rafael; Pardo, Emilio; Muñoz, M. Carmen; Cano, Joan

doi:10.1016/j.ica.2006.07.064

Cited by 14 publications

(7 citation statements)

References 60 publications

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“…The shift for each reduction is somewhat larger if the monodentate carboxylates are coordinated perpendicular to the Mn-(μ-O) 2 -Mn plane (as in 1 ) than if they are coordinated in the plane (as in 2 ), but the differences are not pronounced. There are few reports in the literature of IR stretching frequencies of monodentate carboxylate ligands to high-valent Mn dimers. ,, In most studies, the ν a (COO) and ν s (COO) stretching frequencies are measured in the solid state and are not unambiguously assigned, which make comparisons with our study difficult. The dimeric complex [Mn 2 O 2 (pic) 4 ] n − (picH = picolylic acid) was studied in both the Mn 2 IV,IV ( n = 0) and Mn 2 III,IV ( n = 1) oxidation states, but the structure was not reported.…”

Section: Discussionmentioning

confidence: 79%

FTIR Study of Manganese Dimers with Carboxylate Donors As Model Complexes for the Water Oxidation Complex in Photosystem II

2012

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The carboxylate stretching frequencies of two high-valent, di-μ-oxido bridged, manganese dimers has been studied with IR spectroscopy in three different oxidation states. Both complexes contain one monodentate carboxylate donor to each Mn ion, in one complex, the carboxylate is coordinated perpendicular to the Mn-(μ-O)(2)-Mn plane, and in the other complex, the carboxylate is coordinated in the Mn-(μ-O)(2)-Mn plane. For both complexes, the difference between the asymmetric and the symmetric carboxylate stretching frequencies decrease for both the Mn(2)(IV,IV) to Mn(2)(III,IV) transition and the Mn(2)(III,IV) to Mn(2)(III,III) transition, with only minor differences observed between the two arrangements of the carboxylate ligand versus the Mn-(μ-O)(2)-Mn plane. The IR spectra also show that both carboxylate ligands are affected for each one electron reduction, i.e., the stretching frequency of the carboxylate coordinated to the Mn ion that is not reduced also shifts. These results are discussed in relation to FTIR studies of changes in carboxylate stretching frequencies in a one electron oxidation step of the water oxidation complex in Photosystem II.

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Section: Discussionmentioning

confidence: 79%

FTIR Study of Manganese Dimers with Carboxylate Donors As Model Complexes for the Water Oxidation Complex in Photosystem II

2012

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“…Moreover, the Mn-O b -Mn angle is also smaller (~96 • in contrast with ~104 • for Mn II complexes). DFT studies of high-valence [Mn 2 (m-O) 2 ] n+ systems, reported by Ruiz-Garcia et al, 28 reveal that in these compounds the magnetic coupling is dominated by the in-plane d x 2 -y 2 type superexchange pathway via the oxo bridges with a small, but non negligible, contribution from direct d x 2 -y 2 type Mn ◊ ◊ ◊ Mn s-bond. For Mn II complexes, with larger Mn ◊ ◊ ◊ Mn distances, the degree of this overlap must be very small and the d x 2 -y 2 /d x 2 -y 2 interaction would be only through the bridge, decreasing drastically the antiferromagnetic contribution.…”

Section: Magnetic Propertiesmentioning

confidence: 97%

A μ1,1- or μ1,3-carboxylate bridge makes the difference in the magnetic properties of dinuclear MnII compounds

et al. 2010

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Six new dinuclear Mn(II) compounds with carboxylate bridges have been synthesized and characterized by X-ray diffraction: [{Mn(phen)(2)}(2)(μ-RC(6)H(4)COO)(2)](ClO(4))(2) with R = 2-Cl (1), 2-CH(3) (2), 3-Cl (3), 3-CH(3) (4), 4-Cl (5) and 4-CH(3) (6). Compounds 1 and 2 show two μ(1,3)-carboxylate bridges in a syn-anti mode while compounds 3-6 present a very uncommon coordination mode of the carboxylate ligand: the μ(1,1)-bridge. The magnetic properties of these compounds are very sensitive to the bridging mode of the carboxylate ligands. While compounds 1 and 2 (μ(1,3)-bridge) display antiferromagnetic interactions, with J values of -1.41 and -1.66 cm(-1), respectively, compounds 3-6 (μ(1,1)-bridge) show ferromagnetic interactions, with J values of 1.01, 0.98, 1.04 and 1.06 cm(-1), respectively. It is worth noting that compounds 3-6 are the first of their class to be magnetically characterized. The EPR spectra at 4 K for compounds with antiferromagnetic coupling (1 and 2) are more complex than those for compounds with a ferromagnetic interaction (3-6). Quite good simulations can be obtained with the ZFS parameters of the Mn(II) ion D(Mn) ~ 0.095 cm(-1) and E(Mn) ~ 0.025 cm(-1) for compounds 1 and 2 and D(Mn) ~ 0.060 cm(-1) and E(Mn) ~ 0.004 cm(-1) for compounds 3-6.

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“…[14][15][16][17][18] A number of model manganese complexes including 1-4 Mn atoms have been investigated. 19 Among these, the group of model manganese dimer complexes containing dimers bridged by one 20 and two m-oxo bridges 4,[21][22][23][24] are the most studied ones. In particular, the present work is in line with studies on biomimetic binuclear manganese catalysts performed by Siegbahn et al, 5 Brudvig et al 23 and McKenzie et al 25 Building on the results found for these biomimetic systems several channels for O-O bond formation can be identified.…”

Section: Introductionmentioning

confidence: 99%

Electrocatalytic oxygen evolution from water on a Mn(iii–v) dimer model catalyst—A DFT perspective

Busch

Ahlberg

Panas

2011

Phys. Chem. Chem. Phys.

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A complete water oxidation and oxygen evolution reaction (OER) cycle is monitored by means of density functional theory (DFT). A biomimetic model catalyst, comprising a μ-OH bridged Mn(III-V) dimer truncated by acetylacetonate ligand analogs and hydroxides is employed. The reaction cycle is divided into four electrochemical hydrogen abstraction steps followed by a series of chemical steps. The former employ the tyrosine/tyrosyl redox couple acting as electron and proton sink, thus determining the reference potential. Stripping hydrogen from water leads to the formation of two highly unstable Mn(V)=O/Mn(IV)-O˙ moieties, which subsequently combine to form a μ-peroxy O-O bond. O(2) evolution results from subsequent consecutive replacement of the remaining Mn-O bonds by water. A Zener "spintronic" type mechanism for virtually barrierless O(2) evolution is found. The applicability of DFT is discussed and extended to include the rate-limiting steps in the OER. Rather than attempting to compute transition states where KS-DFT is unreliable, an upper bound for the activation barrier of the O-O bond formation step is estimated from the hessians of the relevant intermediates.

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High-valent bis(oxo)-bridged dinuclear manganese oxamates: Synthesis, crystal structures, magnetic properties, and electronic structure calculations of bis(μ-oxo)dimanganese(IV) complexes with a binucleating o-phenylenedioxamate ligand

Cited by 14 publications

References 60 publications

FTIR Study of Manganese Dimers with Carboxylate Donors As Model Complexes for the Water Oxidation Complex in Photosystem II

FTIR Study of Manganese Dimers with Carboxylate Donors As Model Complexes for the Water Oxidation Complex in Photosystem II

A μ1,1- or μ1,3-carboxylate bridge makes the difference in the magnetic properties of dinuclear MnII compounds

Electrocatalytic oxygen evolution from water on a Mn(iii–v) dimer model catalyst—A DFT perspective

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