Browsing by Author "Taban, G"

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    Reduction of [CP2*Mo2O5] by thioglycolic acid in an aqueous medium
    Demirhan, F; Taban, G; Baya, M; Dinoi, C; Daran, JC; Poli, R
    Compound [CP*2Mo2O5] reacts with thioglycolic acid, HSCH2COOH, in an acidic (CF3COOH) mixed water-methanol solvent, to yield compound [{Cp*Mo(mu-SCH2CO2)}(2)(mu-S)]. During this reaction, the thioglycolic acid acts as a reducing agent, as a ligand, and provides a sulfide ion for the Mo-S-Mo bridge. The molecular structure of the product can be described as containing two four-legged piano stools that share three legs. The Mo-Mo distance of 2.792(7) angstrom indicates metal-metal bonding, in agreement with the compound diamagnetism. (c) 2005 Elsevier B.V. All rights reserved.
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    Aqueous reduction of [Cp*2W2O51]: Characterization of the triangular clusters [Cp*3W3O4(OH)2]2+ and [Cp*3W3O6]+ - Comparison with molybdenum
    Dinoi, C; Sözen, P; Taban, G; Dernir, D; Demirhan, F; Prikhodchenko, P; Gun, J; Lev, O; Daran, JC; Poli, R
    Zinc reduction Of CP * 2W2O5 in an acidified water-methanol medium affords the green 3-electron trinuclear cluster [CP*3W3O4(OH)(2)](+2), isolated and crystallographically characterized as the triflate salt, 1. Upon exposure to air, this complex is oxidized to a related 2-electron cluster, [Cp * 3W3O6], which was crystallized and characterized in three different salts, 2-4. The 3-electron cluster exhibits a near-tetragonal frozen-glass EPR spectrum, and it shows evidence of coupling of the unpaired electron to only one of the three W atoms. The two-electron cluster is diamagnetic. An electro-spray ionization MS' study revealed a stepwise expulsion of neutral [CP*WO2] units as the main fragmentation process. DFT calculations unveiled the intimate details of the electronic structures of these complexes and fully rationalized the structural and spectroscopic properties.
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    Improved syntheses Of [CP*2Mo2O5] and [CP*2W2O5]: Structural characterization of Na[Cp*MoO3].5H2O and [CP*2W2O5]
    Dinoi, C; Taban, G; Sözen, P; Demirhan, F; Daran, JC; Poli, R
    Use of aqueous conditions and the ROOH (R = tBu or H) compounds as oxidizing agents affords a simple two-step, one-pot synthetic procedure leading to [Cp*2M2O5] W = Mo, W) from [M(CO)(6)] selectively and in high yields. The hexacarbonyl compounds are converted to Na[Cp*M(CO)(3)] in refluxing THF, then the mixture is diluted with water (W) or aqueous NaOH (Mo) and directly treated with 6 equiv. of ROOH. Acidification of an aqueous solution of the Na[Cp*MO3] product affords spectroscopically pure [Cp2M2O5] in high isolated yields (global yields from [M(CO)(6)], for R = tBu: Mo, 91%; W, 87%). The X-ray structures of Na[Cp*MoO3].5H(2)O and [Cp*2W2O5] are also reported. (c) 2007 Elsevier B.V. All rights reserved.