Controlled Redox Conversion of New X-ray-Characterized Mono- and Dinuclear Heptacoordinated Mn(II) Complexes into Di-μ-oxo-dimanganese Core Complexes

Hureau, Christelle; Blanchard, Sébastien; Nierlich, Martine; Blain, Guillaume; Rivière, Éric; Girerd, Jean‐Jacques; Anxolabéhère‐Mallart, Elodie; Blondin, Geneviève

doi:10.1021/ic035332u

Cited by 31 publications

(36 citation statements)

References 58 publications

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“…Preparation of 1 and 2. which is issued from the hyperfine interaction of I = 5/2 Mn nuclear spin with S = 5/2 electronic spin, could be evidenced. The lack of hyperfine structure indicates that Mn 2+ ions in 2 are indeed magnetically interacting [13], which is also in agreement with the crystal structure and magnetic studies.…”

supporting

confidence: 88%

A mononuclear Mn2+ complex based on a novel tris-(ethyl acetate) pendant-armed tetraazamacrocycle: Effect of pyridine on self-assembly and weak interactions

Wen

Geng

Yin

et al. 2012

Inorganic Chemistry Communications

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supporting

confidence: 88%

A mononuclear Mn2+ complex based on a novel tris-(ethyl acetate) pendant-armed tetraazamacrocycle: Effect of pyridine on self-assembly and weak interactions

Wen

Geng

Yin

et al. 2012

Inorganic Chemistry Communications

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“…The equatorial Mn-O (av.1.88 Å ) and Mn-N (av.1.98 Å ) bond distances are all within the normal range observed for structurally characterized manganese(III) salen type complexes [17, 34]. However, the elongated axial bonds Mn(1)-O(3) ¼ 2.1091(17) Å and Mn(1)-O(4) ¼ 2.3528(19) Å arise due to Jahn-Teller distortion which is consistent with a similar type…”

supporting

confidence: 53%

“…Attempts have also been made to synthesize binuclear/polynuclear complexes with the aim of understanding the effect of the second metal ion on the catalytic activity. Furthermore, it is very important to investigate the function of manganese in some bimetallic metalloproteins [16][17][18][19][20][21][22][23][24][25]. Although considerable advances have been made in understanding the manganese-core structure, a good deal remains to be done to fully understand the function of manganese in metalloproteins.…”

Section: Introductionmentioning

confidence: 99%

Studies on binuclear hydroxo/carboxylato-bridged manganese(III) complexes and a mononuclear manganese(III) complex involving salen type ligands

Biswas

Mitra

Adhikary

et al. 2005

Transition Met Chem

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Synthesis of six hydroxo-bridged binuclear manganese(III) complexes of formulae [MnL-X-MnL](ClO 4 ) [X = OH(1-6)] along with a mononuclear manganese(III) complex (7) [Mn(L)(L¢)(MeOH) 2 ] [HL¢ ¼ 2-(2-hydroxyphen-yl)benzimidazole] and two carboxylate-bridged binuclear manganese(III) complexes (8) and (9) are described. The complexes have been characterized by the combination of i.r., u.v.-vis spectroscopy, magnetic moments and by their redox properties. The electronic spectra of all the complexes exhibit almost identical features consisting of two d-d bands at ca. 550 and 600 nm, one MLCT band at ca. 400 nm, together with two p-p * intra-ligand transitions at ca. 250 nm and ca. 300 nm. Room temperature magnetic data range from l = 2.7-3.0 BM indicates some superexchange between the binuclear metal centers via bridging hydroxo/carboxylato groups. The X-ray crystal structure of the binuclear complex (5) revealed that it has a symmetric Mn III N 2 O 2 core bridged by a hydroxyl group. The Xray analysis of the mononuclear complex (7) showed that the manganese-center possesses a distorted octahedral geometry. Electrochemical properties of hydroxo-bridged manganese(III) complexes (1-6) show identical features consisting of an irreversible and a quasi-reversible reduction corresponding to the Mn 2 III fi Mn II Mn III fi Mn II Mn II couples in the voltammogram. It was found that electron withdrawing substituents on the ligand result in easier reduction. Complex (7) displays an irreversible reduction at 0.08 V and a reversible oxidation at 0.45V assignable to the Mn III fi Mn II reduction and Mn III fi Mn IV oxidation, respectively. The carboxylate-bridged compound (8) exhibits two irreversible oxidations at 0.4 and 0.6 V, probably due to Mn 2 III fi Mn III Mn IV fi Mn IV Mn IV oxidations and shows a quasi-reversible reductive wave at )0.85 V, tentatively assigned to Mn 2 III fi Mn II Mn III reduction.

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“…Thirty seconds after addition of O 2 •– to 1.25 mM 1 , the EPR spectrum exhibits a 16-line signal centered at g = 2 typical of a di-μ-oxo-bridged Mn(IV)Mn(III) species. 31,52−55 The signal is still present at 1.5 min (Figure 7b) but its intensity decreases with time and finally disappears (Figure 7c). This final product could be a Mn(III), Mn(III) 2 , or Mn(IV) 2 complex, inactive in EPR.…”

Section: Resultsmentioning

confidence: 98%

Insights into Second-Sphere Effects on Redox Potentials, Spectroscopic Properties, and Superoxide Dismutase Activity of Manganese Complexes with Schiff-Base Ligands

et al. 2019

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Six Mn-Schiff base complexes, [Mn(X-salpn)] 0/+ (salpn = 1,3-bis(sal-ic-ylidenamino)propane, X = H [ 1 ], 5-Cl [ 2 ], 2,5-F 2 [ 3 ], 3,5-Cl 2 [ 4 ], 5-NO 2 [ 5 ], 3,5-(NO 2 ) 2 [ 6 ]), were synthesized and characterized in solution, and second-sphere effects on their electrochemical and spectroscopic properties were analyzed. The six complexes catalyze the dismutation of superoxide with catalytic rate constants in the range 0.65 to 1.54 × 10 6 M –1 s –1 obtained through the nitro blue tetrazolium photoreduction inhibition superoxide dismutases assay, in aqueous medium of pH 7.8. In solution, these compounds possess two labile solvent molecules in the axial positions favoring coordination of the highly nucleophilic O 2 •– to the metal center. Even complex 5 , [Mn(5-(NO 2 )salpn) (OAc) (H 2 O)], with an axial acetate in the solid state, behaves as a 1:1 electrolyte in methanolic solution. Electron paramagnetic resonance and UV–vis monitoring of the reaction of [Mn(X-salpn)] 0/+ with KO 2 demonstrates that in diluted solutions these complexes behave as catalysts supporting several additions of excess O 2 •– , but at high complex concentrations (≥0.75 mM) catalyst self-inhibition occurs by the formation of a catalytically inactive dimer. The correlation of spectroscopic, electrochemical, and kinetics data suggest that second-sphere effects control the oxidation states of Mn involved in the O 2 •– dismutation cycle catalyzed by complexes 1–6 and modulate the strength of the Mn-substrate adduct for electron-transfer through an inner-sphere mechanism.

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Controlled Redox Conversion of New X-ray-Characterized Mono- and Dinuclear Heptacoordinated Mn(II) Complexes into Di-μ-oxo-dimanganese Core Complexes

Cited by 31 publications

References 58 publications

A mononuclear Mn2+ complex based on a novel tris-(ethyl acetate) pendant-armed tetraazamacrocycle: Effect of pyridine on self-assembly and weak interactions

A mononuclear Mn2+ complex based on a novel tris-(ethyl acetate) pendant-armed tetraazamacrocycle: Effect of pyridine on self-assembly and weak interactions

Studies on binuclear hydroxo/carboxylato-bridged manganese(III) complexes and a mononuclear manganese(III) complex involving salen type ligands

Insights into Second-Sphere Effects on Redox Potentials, Spectroscopic Properties, and Superoxide Dismutase Activity of Manganese Complexes with Schiff-Base Ligands

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