Höhere Oxydationsproducte des Chroms

Production of superoxide radical during the decomposition of potassium peroxochromate(V)

“…Methylene Blue, horse heart cytochrome c type III, bovine pancreatic trypsin, type III, and beef liver catalase were obtained from Sigma Chemical Co. Ferrocytochrome c was prepared by reduction with sodium dithionite followed by anaerobic dialysis. Crystalline potassium tetraperoxochromate(V) was prepared by treating Cr03 with 30% hydrogen peroxide, in the presence of concentrated KOH, according to the method of Riesenfeld (Riesenfeld et al, 1905). Pyrophosphate buffers were prepared by adding concentrated sulfuric acid to a sodium pyrophosphate solution until the desired pH was obtained.…”

Vibrational spectra of the peroxochromates (NH4)3[Cr(O2)4], K3[Cr(O2)4] and Rb3[Cr(O2)4]

“…the [Cr O 2 4 ] 3 ion (site group symmetry D 2d ) or the peroxo groups (see Table 4 peroxochromates related to different groups of vibrations: in the region with Q > 800 cm 1 we expect the stretching vibrations of the peroxo groups, for 700 cm 1 > Q > 400 cm 1 the Cr-O stretching vibrations of the peroxochromate ion and for 400 cm 1 > Q > 200 cm 1 the bending vibrations of the peroxochromate ion should be observed, while the translational lattice vibrations and the librations of the [Cr O 2 4 ] 3 ion will occur below 200 cm 1 . In the case of the ammonium compound, in addition to the vibrations of the K 3 [Cr O 2 4 ] type the internal vibrations of the ammonium ions and their librational modes are observed in the spectra.…”

“…Red peroxochromates were first discovered by Riesenfeld et al 1 in 1905 and have subsequently been investigated intensively with respect to the unusual oxidation state, CV, of the chromium. The structure of the potassium compound K 3 [Cr O 2 4 ] has been investigated by Wilson 2 and by Stomberg and Brosset.…”

“…EXPERIMENTAL K 3 [Cr O 2 4 ] was prepared according to the procedure given in the literature. 1 For the preparation of NH 4 3 [Cr O 2 4 ], 6.25 ml of a 50 wt% solution of CrO 3 and 25 ml of 25 wt% ammonia were mixed and diluted with 37.5 ml water. The resulting solution was cooled with an ice-sodium chloride mixture to 5°C and 12.5 ml of hydrogen peroxide solution (30 wt%) were added slowly under vigorous stirring.…”

Vibrational spectra of the peroxotantalates (NH4)3[Ta(O2)4], K3[Ta(O2)4], Rb3[Ta(O2)4] and Cs3[Ta(O2)4] and the crystal structure of Rb3[Ta(O2)4]

“…In 1905 Riesenfeld [1] discovered red peroxochromates with the unusual oxidation state +V of the chromium. Later, during his studies on the structure of the potassium peroxochromate K 3 [Cr(O 2 ) 4 ] Wilson [2] prepared a series of compounds in which the chromium is replaced by pentavalent niobium or tantalum and which he describes as isotypic to K 3 [Cr(O 2 ) 4 ].…”