Search results for "MOLYBDENUM"

Syntheses, characterization and properties of Cu(II)-, Mo(VI)- and U(VI) complexes with diaminotetraphenolate ligands

2013

CCDC 188051: Experimental Crystal Structure Determination

2003

Related Article: J.M.Herrera, D.Armentano, G.de Munno, F.Lloret, M.Julve, M.Verdaguer|2003|New J.Chem.|27|128|doi:10.1039/b206124b

Quadruply-bonded dimolybdenum compounds: Reactivity towards TCNE. Structural evidences for the 1-D polymer [Mo2(O2 CCF3)4(TCNE)]∞

2005

cited By 3; International audience; Reaction of [Mo2(O2CR)4] (R = CF 3, 1) with TCNE in toluene affords the new compound [Mo2(O2CCF3)4 (TCNE)·6H5CH3 (2). The structure of 2 is built on [Mo2(O2 CCF3)4] fragments having the usual paddlewheel structure of 1 (Mo-Mo 2.1117(8) Å) and TCNE units. Each polynitrile moiety acts as a bridging ligand between two Mo2 fragments (Mo-N 2.875(4) Å) affording 1-D polymeric chains crossing in the crystal; the toluene molecules occupy the cavities between the chains. 13C NMR, IR and electrochemical data clearly show that formation of 2 does not involve electron density transfer from dimolybdenum fragment to the TCNE unit, which remains in 2 in its neutral stat…

ChemInform Abstract: Oxidative (Cross-)Coupling Reactions Mediated by C-H Activation of Thiophene Derivatives by Using Molybdenum(V) Reagents.

2015

The use of MoCl5 renders possible the preparation of various synthetically important polycyclic thienoacenes.

Theoretical Studies of the Reactivity of Cyclopentadienyl Nitrosyl Alkyl Species of Molybdenum and Tungsten

2000

International audience; The reactivity differences observed experimentally for Cp*W(NO)(CH2CMe3)2 and CpMo(NO)(CH2CMe3)2 have been investigated using density functional theory (DFT) techniques. The reactions of the CpW(NO)(CH2) model complex with NH3 and CH4 are more exothermic and have lower activation barriers than the corresponding processes for CpMo(NO)(CH2). The η2(C,H) methane complex CpM(NO)(CH2)(CH4) (M = Mo, W) can undergo two competitive processes:  C−H activation to afford CpM(NO)(CH3)2 or loss of methane. The relative barrier heights are almost identical for M = W, whereas the formation of CpM(NO)(CH3)2 is significantly disfavored for M = Mo. The activation of C−H and N−H bonds …

Tungsten oxides as catalysts in selective oxidation

1983

Abstract The reaction of allyl iodide was studied at the surface of four tungsten oxides and molybdenum trioxide. On WO2.95 and MoO3, in which crystallographic shear structures are formed on reduction, acrolein is produced at 300–400 °C, whereas W18O49 and WO2, which do not show this property, are inactive, as is WO3. It is concluded that the transformation of a corner-linked into an edge-linked arrangement of metal-oxygen octahedra provides a facile route for insertion of oxygen into a hydrocarbon molecule.

Compounds of molybdenum(VI) with aspartic acid: A spectrophotometric and potentiometric study of the formation and interconversion equilibria in aque…

1990

Addition of Na2MoO4 to an excess of aspartic acid (AspH2) can produce any of four different complexes depending on the pH, namely [MoO3(Asp)]2−, [Mo2O5(Asp)2]2−, [Mo2O4(OH)(Asp)2]− and [Mo2O4(Asp)2]. The ranges of formation of these species with pH, the number of equivalents of acid necessary for their formation, and their stoichiometries, condensation degrees and stability constants, have been calculated by potentiometric and spectrophotometric techniques. The aspartic acid acts as a tridentate ligand in all cases.

Modular Access to 9,9-Spirobifluorenes by Oxidative Coupling Using Molybdenum Pentachloride

2013

The strong oxidizing agent molybdenum pentachloride was used for an efficient direct C–C bond formation of 9,9-diarylfluorenes to the corresponding 9,9-spirobifluorenes. Thus, a versatile method that is compatible with labile groups, such as iodo moieties, was established. By this approach important building blocks for light emitting polymers were synthesized in high yields.

The catalytic-thermometric determination of molybdenum in steels based on the hydrogen peroxide-iodide indicator reaction

1990

Abstract The Mo VI -catalysed hydrogen peroxide-iodide reaction has been optimised for thermometry in an HCl medium using the initial slope method. The substitution of sodium perborate by H 2 O 2 and the conversion of the reaction to a process showing a Landolt effect are considered and discussed. The linear range extended from 0.2 μg Mo VI ml −1 to 1.2 μg Mo VI ml −1 with a detection limit of 0.06 μg Mo VI ml −1 . Interferences were also studied. The optimised procedure was applied to the evaluation of molybdenum in steels after extraction with α-benzoinoxime in chloroform.

Synthesis, Structure and Catalytic Properties of Dinuclear Mo-VI Complexes with Ditopic Diaminotetraphenols

2013

MoVI complexes with novel ditopic diaminotetraphenol ligands have been prepared by using a one-pot procedure in methanol or DMSO with [MoO2(acac)2] (acac = acetylacetonate) as the molybdenum source. The complexes were characterised with X-ray diffraction, NMR spectroscopic studies, elemental analysis and IR spectroscopy. In the solid state, the compounds represent either a rodlike molecular or oxido-bridged polymeric structure. The catalytic activity of the complexes was investigated by oxidising benzyl alcohol and 1-phenylethanol with hydrogen peroxide to the corresponding aldehyde and ketone, respectively. Furthermore, the catalytic activity was surveyed also in epoxidation of cyclooctene.