Zur struktur der triperoxofluorovanadate(V), A2I[V(O2)3F] (A ≡ NH4+, K+, Cs+)

Westermann, Katja; Leimkühler, Manfred; Mattes, R.

doi:10.1016/0022-5088(88)90085-9

Cited by 10 publications

(2 citation statements)

References 12 publications

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“…The signal at g iso = 1.9764 is assigned as being due to [Cr(O 2 ) 3 (OH)] 2- ( III ) This is expected to have a struc ture similar to that of [V(O 2 ) 3 (F)] 2- , which has been characterized by X-ray crystallography …”

Section: Discussionmentioning

confidence: 99%

EPR Spectroscopic Studies on the Formation of Chromium(V) Peroxo Complexes in the Reaction of Chromium(VI) with Hydrogen Peroxide

Zhang

Lay

1998

Inorg. Chem.

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The Cr(V) products of the reaction of Cr(VI) with H2O2 were studied by EPR spectroscopy. In addition to the well-characterized tetrakis(η2-peroxo)chromate(V) complex, [Cr(O2)4]3-, with g iso = 1.9723 (A iso = 18.4 × 10-4 cm-1), three new species were observed with isotropic EPR parameters, g iso = 1.9820, g iso = 1.9798 (A iso = 16.3 × 10-4 cm-1), and g iso = 1.9764 (A iso = 18.1 × 10-4 cm-1). While [Cr(O2)4]3- is stable at high concentrations of H2O2 and in alkaline solution, the species with a signal at g iso = 1.9798 is stabilized at low relative concentrations of H2O2 and in neutral solution. The signal at g iso = 1.9764 is most prominent in weakly acidic (pH = 4−7) solutions and low relative concentrations of H2O2. Finally, the signal at 1.9820 is only minor and is apparent at low pH values and low [H2O2]. From the pH and [H2O2] dependences, and by analogy with the V(V) chemistry, the species giving rise to the signals at g iso = 1.9820, g iso = 1.9798, and g iso = 1.9764 are assigned as the oxo(η2-peroxo)chromium(V), [Cr(O)(O2)(OH2) n ]+, aquaoxobis(η2-peroxo)chromate(V), [Cr(O)(O2)2(OH2)]-, and the hydroxotris(η2-peroxo)chromate(V), [Cr(O2)3(OH)]2-, complexes, respectively. The implications of these Cr(V) peroxo species for understanding the in vitro DNA damage caused by Cr(VI) and H2O2 and the genotoxicity of carcinogenic Cr(VI) complexes are discussed.

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Section: Discussionmentioning

confidence: 99%

EPR Spectroscopic Studies on the Formation of Chromium(V) Peroxo Complexes in the Reaction of Chromium(VI) with Hydrogen Peroxide

Zhang

Lay

1998

Inorg. Chem.

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“…In a recent review 3 the only V triperoxide listed as structurally characterized is [V(O 2 ) 3 F] 2- . However, the experimental structure has large estimated standard deviations in the X-ray positional parameters . Hence, ECP calculations were carried out on C 2 -[V(O 2 ) 3 F] 2- , the symmetry that was indicated by experiment.…”

Section: Resultsmentioning

confidence: 99%

Molecular Modeling of Vanadium Peroxides

1997

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A computational study of vanadium peroxides (L n V(O 2 ) m ; m ) 0-4), important for their biochemical and catalytic activity, is reported. In the compounds studied, ancillary ligands (L n ) are generally the hard, oxygen-and nitrogenbased donor ligands, e.g., carboxylates and pyridines, prevalent in the coordination chemistry of vanadium peroxides. The utility of estimating missing metal-dependent molecular mechanics (MM) parameters from quantum calculations is demonstrated. Given the limited vibrational data for many families of transition metal complexes, quantum calculations are a viable source for parameters to use in development of force fields. A conformational search of [V(O 2 ) 3 F] 2using MM yielded a geometry inconsistent with experiment, but consistent with ab initio geometry optimizations. A reinvestigation of this structure is therefore of interest. Molecular mechanics provides a quick and accurate method for obtaining structural information. The level of agreement for structural prediction is competitive with that obtained using more computationally intensive methods in much less time. In most cases it was seen that MM and quantum predictions reinforced each other, lending greater confidence in modeling results. In other cases, classical and quantum results were in conflict, indicating the need for further higherlevel, quantum calculations. Hence, MM and low-level quantum calculations, when used together, provide a valuable method for quickly probing the conformational space of large coordination complexes.

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