Chromium pentavalent

Naegele JR, Ghijsen J (1985) Localization and Hybridization of 5f States in the Metallic and Ionic Bond as Investigated by Photoelectron Spectroscopy. 59160 197-262 Nag K, Bose SN (1985) Chemistry of Tetra-and Pentavalent Chromium. 63 153-197 Naletvajski RE (1993) The Hardness Based Molecular Charge Sensitivities and Their Use in the Theory of Chemical Reactivity. 80 115-186 Natan MJ, see Hoffman BM (1991) 75 85-108 Neilands JB, see Liu A (1984) 58 97-106 Neilands JB, see Chimiak A (1984) 58 89-96... 

Westheimer has also reviewed the induced oxidations by the Cr(VI)-As(III) couple of iodide, bromide and manganous ions vide supra). The induction factor of 0.5 for Mn(II) implies an intermediate tetravalent chromium species however, the factor of 2 for iodide points to a pentavalent chromium intermediate. Both... 

Pentavalent Chromium. The radiation-induced formation of unstable lower oxidation states is not limited to the cations. As an example of the anions, Cr04-2 or Cr207 2 have been investigated. In acid media, the presence of dichromate markedly decreases the H atom yields, while in alkali hydroxide solutions an absorption band (Xmax = 585 m/x) and a characteristic ESR signal both attributable to the trapped... 

The first oxoaUcyl of chromium(V), ( -C5Me5)CrO(Me)2, was prepared via oxygen transfer from trimethylamine N-oxide to the Cr precursor ( -C5Me5)Cr(py)Me2. Its effective magnetic moment at 285 K, 1.76 J,b, is consistent with the presence of pentavalent chromium. At ambient temperature and pressure, this complex does not function as an ethylene polymerization catalyst however, it does react with the starting material to give the Cr dimer [( l -C5Me5)Cr(Me)2]2(Ai2-0). Another chromium(V) alkyl, namely, dinuclear [Cp Cr(0)Me]2(/tr-0), was produced by the reaction of [Cp Cr(/u.-Me)]2 with O2. 

Hexavalent chromium is unstable in the body and is reduced intracellularly (by many substances including ascorbate and glutathione) providing very reactive pentavalent chromium and trivalent chromium. Both of these intermediates can alter DNA. 

The most common oxidation states of chromium in inorganic compounds are 11, III, and VI. By comparison, there are few stable compounds of tetravalent or pentavalent chromium these oxidation states are largely represented by reactive intermediates in redox reactions. rr-Acid ligands like CO seen Acid Ligand) stabilize chromium in very low formal oxidation states (down to —IV ). Table 3 lists oxidations states and coordination environments for representative chromium compounds. 

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