Formation of a dithiophosphinate ligand Ph2PS2 by sulfur insertion into the metal-phosphido bond on heterobimetallic phosphido-bridged complex Cp(CO)(2)W(mu-PPh2)Mo(CO)(5): A rare example of a neutral six-electron mixed-metal cluster with a Mo2WS4 core

Reflux of a dichloromethane solution of elemental sulfur and phosphido-bridged heterodinuclear complex Cp( CO)(2)W(mu- PPh2) Mo( CO)(5) ( 1) afforded Cp( S) W(mu- S)(2)Mo( S)( S2PPh2) ( 2) and a neutral six- electron mixed- metal incomplete cubane- like cluster, CpW(mu(3)- S)(mu- S)(2)Mo-2(mu- S)(mu- S2PPh2)( S2PPh2) 2 ( 3), together with known compounds Cp( CO)(3)W(mu- PPh2) Mo(CO)(5) and (CpW(S)(mu-S))(2). The electron- deficient 28e heterodinuclear complex 2 is stabilized via S(p(pi)) -> Mo( d) ligand- to- metal dative pi- bonding interactions. Room-temperature stirring of a THF solution of 2 and DMAD ( dimethyl acetylenedicarboxalate) yielded compounds Cp( S2C2( COOMe2))(2)W(mu- S)(2)Mo(O)( S2PPh2) ( 4) and Cp( S2C2( COOMe2)(2)) W(mu- S)(2)W(O) Cp ( 5). Compounds 2-5 were characterized by single- crystal X- ray diffraction analysis. Molecular structures of 2 and 3 reveal sulfur insertion into the metal-phosphido bond on 1, resulting in a dithiophosphinate ligand Ph2PS2. Formation of the C-S bonds in 4 and 5 has resulted through the reaction of sulfide ligands on 2 and DMAD

Supported vanadium oxide catalysts in selective oxidation of ethanol: Comparison of TiO2/SiO2 and ZrO2/SiO2 as supports

Highly dispersed vanadia supported on TiO2/SiO2 and ZrO2/SiO2 were synthesized through the grafting method. The physical and chemical properties were investigated by nitrogen adsorption/desorption, X-ray diffraction, H-2 temperature programmed reduction, and temperature programmed desorption. Moreover, their performances in selective oxidation of ethanol were evaluated. With almost identical vanadia loading, VOx/ZrO2/SiO2 exhibits better catalytic behaviors than that of VOx/TiO2/SiO2. This can be attributed to the nature of enhanced support. (c) 2007 Elsevier B.V. All rights reserved

Synthesis of a reusable oxotungsten-containing SBA-15 mesoporous catalyst for the organic solvent-free conversion of cyclohexene to adipic acid

An oxotungsten-silica mesoporous structure (WSBA-15) has a hierarchical crystalline architecture in which the W dopants possess tetrahedral coordination geometries for the mixed-valence states W6+, W5+, and W4+. The WSBA-15 catalyst can be recycled-without any loss of activity-for the direct oxidation (30% H2O2,) of cyclohexene to colorless, crystalline adipic acid (55% yield) under organic solvent-free conditions. (C) 2006 Elsevier B.V. All rights reserved