Divalent Oxidation State Research Articles

Physico-chemical properties of chickpea lipoxygenases

Purified lipoxygenase isoenzymes from chickpea ( Cicer arietinum) cv Pedroxillano are single polypeptide chains with M rs of 96 000–97 000, determined by hydrodynamic and electrophoretic methods. Both isoenzymes difrered in pI, 4.92 for CL-1 and 4.74 for CL-2. Each isoenzyme contained one atom of iron in a divalent oxidation state. CL-1 contained 760 amino acid residues and CL-2 753 residues, with a high proportion of hydrophobic amino acids, particularly proline and leucine. Eight and seven cysteines were also present, two and three of which were as free sulphydryl residues, in CL- 1 and CL-2, respectively. Thiols, sulphur bridges and carboxyl and amine groups seemed to be essential in the maintenance of a catalytically active tertiary structure in both isoenzymes. CL-2 formed mainly 13-hydroperoxy-(9 Z, 11 E)-octadecadienoic acid from linoleic acid, while CL- 1 yielded almost equal proportions of the 9-and 13-hydroperoxides, and the 9- and 13-ketodienes.

Oxidation state of Fe and Ti ions implanted in yttria-stabilized zirconia studied by XPS

The oxidation state of Fe and Ti ions implanted in yttria stabilized zirconia (YSZ) was studied by XPS (X-ray photoelectron spectroscopy) in combination with depth profiling using Ar+ sputtering. In the “as-implanted” state of the sample Fe was found to be present as Fe3+, Fe2+ and as metallic Fe0. This is in agreement with earlier conversion electron Mossbauer Spectroscopy measurements. For Ti-implanted YSZ in the “as-implanted” state the majority of the Ti is present as Ti4+, Ti3+, and Ti2+ ions, while a part of the Zr cations is present in the divalent oxidation state (Zr2+). After oxidation in air, the Fe and Ti ions are present only in the valence three and four oxidation states, respectively.

The role of nickel and iron-sulfur centers in the bioproduction of hydrogen

Abstract

Divalent titanium chemistry. Synthesis, reactivity, and x-ray and neutron diffraction studies of Ti(BH4)2(dmpe)2 and Ti(CH3)2(dmpe)2

Low valent organotitanium complexes have been implicated as Ziegler-Natta olefin polymerization catalysts and as stoichiometric reagents in organic synthesis. However, very few low-valent alkyls of titanium have been reported, and, in particular, the divalent oxidation state of titanium is virtually unexplored. The authors now report the synthesis and characterization of the unusual divalent tetrahydroborate complex Ti(BH/sub 4/)/sub 2/(dmpe)/sub 2/, 1, and its conversion to the methyl compound Ti(CH/sub 3/)/sub 2/(dmpe)/sub 2/, 2. Complex 2 is unique among octahedral complexes of the 3d metals in being low-spin within the t/sub 2g/ manifold and exhibits very unusual NMR features for the titanium methyl group.

Electrochemical and spectroscopic studies of the lanthanides in the AlCl3 + 1-n-butylpyridinium chloride melt at 40°C Part I. The Yb(III-II), Sm(III-II) systems

The behaviour of Yb(III-II) and Sm(III-II) couples has been investigated in AlCl 3 +1-n-butylpyridinium chloride (BPC) mixtures at 40°C, by voltammetric and spectrophotometric methods. In very acidic melts, the two trivalent lanthanides can be reduced reversibly and solutions of divalent oxidation states are stable. The E 1/2 potentials measured with respect to an Al electrode dipping in a melt containing 57 mol% of AlCl 3 are constant and located respectively at +1.230 V (Yb) and +0.660 V (Sm). If the acidity of the melt is decreased, the lanthanide cations precipitate and the half-wave potentials exhibit a cathodic shift. These phenomena are explained in terms of cationic chlorocomplexes, depending on the pCl, the oxidation state and the atomic number. Species such as YbCl 2+ , YbCl + and SmCl 2+ , Sm 3+ , Sm 2+ are proposed.

Electrochemical and spectroscopic studies of the lanthanides in the AlCl 3+1-n-butylpyridinium chloride melt at 40°C : Part I. The Yb(III-II), Sm(III-II) systems

The behaviour of Yb(III-II) and Sm(III-II) couples has been investigated in AlCl 3+1-n-butylpyridinium chloride (BPC) mixtures at 40°C, by voltammetric and spectrophotometric methods. In very acidic melts, the two trivalent lanthanides can be reduced reversibly and solutions of divalent oxidation states are stable. The E 1/2 potentials measured with respect to an Al electrode dipping in a melt containing 57 mol% of AlCl 3 are constant and located respectively at +1.230 V (Yb) and +0.660 V (Sm). If the acidity of the melt is decreased, the lanthanide cations precipitate and the half-wave potentials exhibit a cathodic shift. These phenomena are explained in terms of cationic chlorocomplexes, depending on the pCl, the oxidation state and the atomic number. Species such as YbCl 2+, YbCl + and SmCl 2+, Sm 3+, Sm 2+ are proposed.

ChemInform Abstract: COMPLEXATION OF THE LANTHANIDE IONS BY 4,4′(5′)‐DI‐TERT‐BUTYLBENZO‐18‐CROWN‐6 IN PROPYLENE CARBONATE AND STABILIZATION OF THE DIVALENT OXIDATION STATE OF SAMARIUM AND YTTERBIUM

Chemischer InformationsdienstVolume 11, Issue 41 Article ChemInform Abstract: COMPLEXATION OF THE LANTHANIDE IONS BY 4,4′(5′)-DI-TERT-BUTYLBENZO-18-CROWN-6 IN PROPYLENE CARBONATE AND STABILIZATION OF THE DIVALENT OXIDATION STATE OF SAMARIUM AND YTTERBIUM J. MASSAUX, J. MASSAUXSearch for more papers by this authorJ. F. DESREUX, J. F. DESREUXSearch for more papers by this authorC. DELCHAMBRE, C. DELCHAMBRESearch for more papers by this authorG. DUYCKAERTS, G. DUYCKAERTSSearch for more papers by this author J. MASSAUX, J. MASSAUXSearch for more papers by this authorJ. F. DESREUX, J. F. DESREUXSearch for more papers by this authorC. DELCHAMBRE, C. DELCHAMBRESearch for more papers by this authorG. DUYCKAERTS, G. DUYCKAERTSSearch for more papers by this author First published: October 14, 1980 https://doi.org/10.1002/chin.198041081Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume11, Issue41October 14, 1980 RelatedInformation

Complexation of the lanthanide ions by 4,4'(5')-di-tert-butylbenzo-18-crown-6 in propylene carbonate and stabilization of the divalent oxidation state of samarium and ytterbium

Complexation of the lanthanide ions by 4,4'(5')-di-tert-butylbenzo-18-crown-6 in propylene carbonate and stabilization of the divalent oxidation state of samarium and ytterbium

Electrochemistry of lanthanides in molten chloroaluminates: Part I. The electrochemical behaviour of Eu(III), Yb(III) and Sm(III)

The electrochemical behaviour of Eu(III), Yb(III,II) and Sm(III,II) has been investigated in NaCl-AlCl 3 mixtures, in a temperature range between 150 and 250°C. Principal investigation methods are cyclic voltammetry, pulse polarography and chronoamperometry. The three tervalent lanthanides can be reduced reversibly and solutions of divalent oxidation states are stable. E 1/2 potentials measured with respect to an Al electrode in a saturated melt are located respectively at 2.295 V (Eu), 1.630 V (Yb) and 1.080 V (Sm). In acidic chloroaluminates, the three investigated lanthanides are more oxidizing than in other more complexing solvents. If the acidity of the melt is decreased, precipitation of the trichloride (or the dichloride) occurs and the solubility product of the different species is directly related to the cationic size.

Electrochemical studies on the existence of divalent oxidation states of selected actinides in acetonitrile solution

Electrochemical studies on the existence of divalent oxidation states of selected actinides in acetonitrile solution

Polarographic evidence for the divalent oxidation state of californium

Polarographic evidence for the divalent oxidation state of californium

Reaction of europium in liquid ammonia with organic acids including representative organosulfur, organophosphorus acids and an amino acid: d, l- α-alanine

Europium reacts with organic acids in liquid ammonia to give ammoniated compounds in which the metal is in the divalent oxidation state. All the compounds are solids and are characterized by infrared spectra and magnetic susceptibilities. The europium dialaninate is completely soluble in liquid ammonia.