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Oxo Ligands (oxo + ligand)

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Chemistry100%

Selected Abstracts

endo and exo Coordination of Indanol: Synthesis, Isolation and Structural Characterisation of [H3Ru3(endo -Indanol)(C6Me6)2(O)]+ and [H3Ru3(exo -Indanol)(C6Me6)2(O)]+ as Their Tetrafluoroborate Salts

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2004
Ludovic Vieille-Petit
Abstract The reaction of 2,3,4,7-tetrahydro-1H -inden-2-ol with ruthenium chloride hydrate in refluxing ethanol yields the chloro-bridged dinuclear complex [RuCl2(indanol)]2 (1). The mononuclear complex [Ru(indanol)(H2O)3]2+ (2), formed in situ from 1 in aqueous solution, reacts with the dinuclear complex [H3Ru2(C6Me6)2]+ to give a trinuclear arene-ruthenium cluster as a mixture of two isomers, the cations [H3Ru3(endo -indanol)(C6Me6)2(O)]+ (3a) and [H3Ru3(exo -indanol)(C6Me6)2(O)]+ (3b), in a 1:1 ratio. The hydroxy function of the indanol ligand is oriented towards the ,3 -oxo cap of 3a, whereas the OH group is bent away from the metal skeleton of 3b. These two isomers, which can easily be separated by silica-gel chromatography, were isolated and characterised as their tetrafluoroborate salts. The single-crystal X-ray structure analysis of [3a][BF4] shows a strong intramolecular hydrogen bond between the ,3 -oxo ligand and the hydroxyl function, which even persists in acetone solution, as demonstrated by NMR spectroscopy. On the other hand, the hydroxy function of 3b was found to be free in the solid state as well as in solution, as shown by an X-ray crystal structure analysis and by NMR spectroscopy. The catalytic activities of the water-soluble trinuclear cations 3a and 3b for the hydrogenation of benzene to give cyclohexane under biphasic conditions are considerably different, the exo isomer 3b being more active than the endo isomer 3a. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

A Structure-Consistent Mechanism for Dioxygen Formation in Photosystem II

CHEMISTRY - A EUROPEAN JOURNAL, Issue 27 2008

Abstract In recent DFT studies a new mechanism for OO bond formation at the oxygen evolving center (OEC) in photosystem II has been suggested. With the structure of the S4 state required for that mechanism, the structures of the lower S states are investigated herein by adding protons and electrons. A model was used including the full amino acids for the ones ligating the OEC, and in which the backbone positions were held fixed from the X-ray structure. The only charged second-shell ligand Arg357 was also included. An optimized structure for the S1 state was reached with a large similarity to one of those suggested by EXAFS. A full catalytic cycle was derived which can rationalize the structural relaxation in the S2 to S3 transition, and the fact that only an electron leaves in the transition before. Water is suggested to bind to the OEC in the S2 to S3, and S4 to S0 transitions. A new possibility for water exchange is suggested from the final energy diagram. The optimal OO bond formation occurs between an oxygen radical and an oxo ligand. The alternative mechanism, where the oxygen radical reacts with an external water, has a barrier about 20,kcal,mol,1 higher. [source]

Hydrothermal Synthesis and Structural Characterization of the High-Valent Ruthenium-Containing Polyoxoanion [{PW11O39}2{(HO)RuIV,O,RuIV(OH)}]10,

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2008
Su-Wen Chen
Abstract The high-valent ruthenium-containing [{PW11O39}2{(HO)RuIV,O,RuIV(OH)}]10, anion (1) has been synthesized by hydrothermal reaction and characterized by X-ray diffraction, IR, multinuclear (31P and 183W) NMR spectroscopy andelectrochemistry. Single-crystal analysis was carried outon Rb10[{PW11O39}2{(HO)RuIV,O,RuIV(OH)}]·21H2O, which crystallizes in the monoclinic system, space group P21/n, with a = 11.1912(14), b = 21.9257(12), c = 38.7310(96) Å, , = 94.682(19)°, V = 9472(3) Å3, Z = 4. Polyanion 1 consists of two lacunary [,-PW11O39]7, anions connected by a linear {(HO)Ru,O,Ru(OH)}4+ unit. Each ruthenium ion achieves six-coordination through interaction with two terminal oxo ligands from the lacuna of each [PW11O39]7, anion.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

Peroxotungstates and Their Citrate and Tartrate Derivatives

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 8 2006
Shu-Ya Hou
Abstract The reaction of potassium tungstate with the biologically relevant ligands citric and tartaric acid, in the presence of hydrogen peroxide, was investigated to discover the effect of pH variation on the product pattern. The reaction with citric acid led to the formation of the dimer K5[WO(O2)2(Hcit)H(Hcit)(O2)2OW]·6H2O (1; H4cit = citric acid) due to carboxyl-carboxylic acid hydrogen bonding in the pH range 2,5; this complex can also be obtained by an exchange reaction between the oxo ligands of the dimeric hydrogencitrate tungstate K4[W2O5(Hcit)2]·4H2O (6) and H2O2. Interestingly, a novel dimeric peroxotungstate K3[W2O3(O2)4(OH)]·H2O (2), without the coordination of citrate ligands, was isolated in the pH range 7,9, as confirmed by 17O NMR solution studies. The reaction of potassium tungstate with (R,R)-tartaric acid afforded the tartratoperoxotungstate K4[W2O2(O2)4{(R,R)-tart}]·3H2O [3; H4tart = (R,R)-tartaric acid] in the pH range 1,3. The dimeric peroxotungstate K2[W2O3(O2)4(H2O)2]·2H2O (4) was found to react with citric or tartaric acid at pH 2,5 or 2,3, respectively, to give species 1 and 3. Evidence that 1 exists as a dimer in solution is presented. The three complexes were characterized by elemental analysis, IR and NMR spectroscopy, and X-ray structural analyses. The formation of these complexes is dictated by pH, and the thermal stabilities of 1 and 3 vary with the coordinated ligands. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

A dodeca­nuclear manganese(II,III) complex of penta­erythritol

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2007
Arindam Mukherjee
The mol­ecule of the title compound, tetra-,2 -acetato-diaquadi-,2 -chloro-tetra­chloro­tetra­kis[,4 -3-hydroxy-2,2-bis­(oxido­meth­yl)propanol­ato]­tetra­methanoldi-,3 -methanolato-di-,5 -oxo-octa­manganese(II)­tetra­manganese(III), [Mn4IIIMn8II(CH3O)2(C2H3O2)4(C5H9O4)4Cl6O2(CH4O)4(H2O)2], displays a centre of symmetry. The structure of the {Mn4IIIMn8IIO18Cl2}10, core is composed of three layers and features two oxo ligands binding in a rare ,5 -mode. [source]