Search results for "MANGANESE"

Chemistry and reactivity of dinuclear manganese oxamate complexes: Aerobic catechol oxidation catalyzed by high-valent bis(oxo)-bridged dimanganese(I…

2006

[EN] The high-valent bis(oxo)-bridged dimanganese(IV) complexes with the series of binucleating 4.5-X-2-o-phenylenebis(oxamate) ligands (opbaX(2); X = H, Cl, Me) (1a-c) have been synthesized and characterized structurally, spectroscopically and magnetically. Complexes la-c possess unique Mn-2(mu-O)(2) core structures with two o-phenylenediamidate type additional bridges which lead to exceptionally short Mn-Mn distances (2.63-2.65 angstrom) and fairly bent Mn-O-Mn angles (94.1 degrees-94.6 degrees). The cyclovoltammograms of la-c in acetonitrile (25 degrees C, 0.1 M Bu4NPF6) show an irreversible one-electron oxidation peak at moderately high anodic potentials (E-ap = 0.50-0.85 V versus SCE),…

The selection of serum-independent PC12 cells for a more-reliable manganese cytotoxicity test.

2007

A major issue concerning the protocols of heavy metal cytotoxicity tests with PC12 cells was the hypothesis that serum in the culture medium might sequester the metal, thus altering the results obtained. However, serum withdrawal impairs the viability of PC12 cells themselves, thus impeding cytotoxicity testing in the absence of serum. In this study, we repeatedly selected undifferentiated, totally non-adherent PC12 cells in Petri dishes. Surprisingly, we discovered that these cells could survive and proliferate in serum-free medium. Moreover, features such as NGF-responsiveness, resazurin reduction potential, doubling rate, protein content, and basal caspase-3 enzyme activity, were equiva…

Effect of Impurities (Carbon and Manganese) on Iron Oxidation at High Temperature: Impurities-Rare Earth Element (Cerium) Interactions

1997

Apres oxydation du fer pur revetu d'un depot de CeO 2 , (T = 7000C, pO 2 = 0,04 Pa), le cerium se trouve localise dans la couche de wustite sous la forme de CeFeO 3 . La dissolution de cette phase assure l'introduction homogene du cerium a l'interieur de la couche de FeO. Sa formation est attribuee a un processus d'oxydo-reduction entre le depot de CeO 2 et les premiers germes de FeO. Dans le cas des echantillons d'acier Fe-Mn-C, recouverts de CeO 2 , le cerium n'est pas incorpore dans la couche d'oxyde de fer de facon homogene et se retrouve sous la forme de CeO 2 a l'interface oxyde-gaz. Le role de chaque impurete est maintenant bien etabli: le manganese inhibe l'incorporation du cerium d…

Synthesis and X-ray crystal structure of manganese(II) pyridine-2-thiolate

1997

2:1 complexes of pyridine-2(1H)-thione (LH) with manganese(II) were prepared: (LH)2MnCl2, (LH)2MnBr2 and [L2Mn]n. The polymeric chain structure of [L2Mn]n contains a distorted octahedrally coordinated manganese (MnN2S4) with chelating ligands, the N-atoms are in cis positions and the S-atoms of the pyridine-2-thiolates bridging; crystallographic data for [C10H8MnN2S2]n: space group C2/c (monoclinic), and R1 = 0.0571 for 1326 reflexes with Fo4σ(Fo).

Comparative multinuclear magnetic resonance spectroscopic study of transition metal (Cr, W and Mn) mesitylene tricarbonyls and transition metal (Ru a…

1993

Abstract Three mononuclear 1,3,5-trimethylbenzene (mesitylene) carbonyl transition metal complexes, mesitylene tricarbonyl chromium, (CH 3 ) 3 C 6 H 3 Cr(CO) 3 ( 1 ), mesitylene tricarbonyl tungsten, (CH 3 ) 3 C 6 H 3 W(CO) 3 ( 2 ), mesitylene tricarbonyl manganese tetra-fluoroborate, [(CH 3 ) 3 C 6 H 3 Mn(CO) 3 ]BF 4 ( 3 ); and three clusters, mesitylene nonacarbonyl tetracobalt, (CH 3 ) 3 C 6 H 3 Co 4 (CO) 9 ( 4 ), mesitylene carbido tetradecacarbonyl hexaruthenium, (CH 3 ) 3 C 6 H 3 Ru 6 C(CO) 14 ( 5 ) and carbido heptadecacarbonyl hexaruthenium, Ru 6 C(CO) 17 ( 6 ), have been studied by means of 1 H, 13 C and natural abundance 17 O NMR spectroscopy. Generally, the 1 H and 13 C NMR chemi…

FeMnOx-1: A new microanalytical reference material for the investigation of Mn–Fe rich geological samples

2016

Suitable Mn-Fe rich microanalytical reference materials (MRMs) as calibration material for laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) have not been available. The United States Geological Survey (USGS) in collaboration with the Max Planck Institute for Chemistry has prepared a synthetic MRM, FeMnOx-1, with elevated mass fractions of MnO (25 g/100 g), Fe2O3 (8.5 g/100 g) and high mass fractions of 25 trace elements varying between 200 and 5000 mg/kg. This new MRM has been designed as calibration material for a wide range of different Mn-Fe deposits, such as desert/rock varnish, ocean crusts and nodules as well as Mn accumulations in soils and lakes. Small-scale an…

Hexanuclear Manganese(III) Single-Molecule Magnets

2003

Single-crystal EPR study of the bimetallic ferrimagnetic chain MnCu(EDTA)·6H2O

1993

Abstract A single-crystal EPR study of the bimetallic chain compound MnCu(EDTA)·6H2O is reported. The angular dependence of the linewidth is discussed in relation to the magnetic dipole-dipole interaction, manganese zerofield splitting (ZFS) and copper hyperfine coupling. The calculation of the second moments indicates that ZFS is comparable to the dipolar contribution. The EPR data support the one-dimensional character of the compound.

Theoretical Insights into the Ferromagnetic Coupling in Oxalato-Bridged Chromium(III)-Cobalt(II) and Chromium(III)-Manganese(II) Dinuclear Complexes …

2012

Two novel heterobimetallic complexes of formula [Cr(bpy)(ox)(2)Co(Me(2)phen)(H(2)O)(2)][Cr(bpy)(ox)(2)]·4H(2)O (1) and [Cr(phen)(ox)(2)Mn(phen)(H(2)O)(2)][Cr(phen)(ox)(2)]·H(2)O (2) (bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline, and Me(2)phen = 2,9-dimethyl-1,10-phenanthroline) have been obtained through the "complex-as-ligand/complex-as-metal" strategy by using Ph(4)P[CrL(ox)(2)]·H(2)O (L = bpy and phen) and [ML'(H(2)O)(4)](NO(3))(2) (M = Co and Mn; L' = phen and Me(2)phen) as precursors. The X-ray crystal structures of 1 and 2 consist of bis(oxalato)chromate(III) mononuclear anions, [Cr(III)L(ox)(2)](-), and oxalato-bridged chromium(III)-cobalt(II) and chromium(III)-manganese(II) din…

Spectrophotometric determination of adrenaline with an oxidative column in a FIA assembly

1990

Abstract A single channel FIA assembly is proposed for the spectrophotometric determination of adrenaline, the aqueous sample solution is directly injected into the carrier stream leading the sample through a manganese dioxide column at 80°C, and on to the spectrophotometer flow-cell. The calibration graph is linear up to 17 ppm of adrenaline. The influence of other substances has been studied and the method has been applied to the determination of adrenaline in a pharmaceutical formulation.