Z. Naturforsch. 50b, 315-325 (1995); received September 7, 1994 Oxadiene Complex, Molybdenum, Tungsten, X-Ray, Selective Hydrogenation Homoleptic tris(l-oxa-l,3-diene)molybdenum and tungsten complexes are formed as yel­ low, crystalline compounds in 54-80% isolated yield on treatment of the corresponding /3-unsubstituted a,/3-unsaturated ketones with W(CO)3(CH3CH2CN)3 or (y6-C6H6)Mo(CO)3 in ref...

The catalytic mechanism of nitrate reduction by periplasmic nitrate reductases has been investigated using theoretical and computational means. We have found that the nitrate molecule binds to the active site with the Mo ion in the +6 oxidation state. Electron transfer to the active site occurs only in the proton-electron transfer stage, where the Mo(V) species plays an important role in cataly...

Siderophores are iron chelating substances that are also known to bind metals such as Molybdenum and Lead. The pigment produced by P. fluorescens is a siderophore whose ability to bind to different metal ions was investigated in this study. Pigment production was increased in the presence of Sodium, Potassium, Lead, Molybdenum and Cadmium. Siderophores were detected using CAS assay and catechol...

The preparation and characterization of new model complexes for the molybdenum cofactor are reported. The new models are distinctive for the inclusion of pterin-substituted dithiolene chelates and have the formulation Tp(*)MoX(pterin-R-dithiolene) (Tp(*)=tris(3,5,-dimethylpyrazolyl)borate), X=O, S, R=aryl. Syntheses of Mo(4+) and (5+) complexes of two pterin-dithiolene derivatives as both oxo a...

UV-vis diffuse reflectance spectroscopy (DRS) and Raman spectroscopy were used to examine the electronic and molecular structures, respectively, of well-defined Mo(VI) bulk mixed oxide reference compounds ((i) isolated MoO4 or MoO6 monomers, (ii) dimeric O3Mo-O-MoO3, (iii) chains of alternating MoO4 and MoO6 units, (iv) MoO6-coordinated Mo7-Mo12 clusters, and (v) infinite layered sheets of MoO5...

This is a report on the extraction of molybdenum(VI) ions using a supported liquid membrane, prepared by dissolving in kerosene, the extractant Alamine 336 (a long-chain tertiary amine) employed as mobile carrier. A flat hydrophobic microporous membrane was utilised as solid support. Appropriate conditions for Mo(VI) extraction through the liquid membrane were obtained from the results of liqui...

High-resolution molybdenum K-edge X-ray emission spectroscopy (XES) was used to characterize the K beta(4) and K beta' ' valence-to-core transition bands in the oxo-Mo compounds K(2)MoO(4), MoO(S(2)CNEt(2))(2), and MoO(2)(S(2)CNEt(2))(2). The K beta(4) and K beta' ' emission bands are attributed to transitions to the Mo 1s core hole from molecular orbitals possessing primarily molybdenum 4d and...

Alkyne metathesis by molybdenum and tungsten alkylidyne complexes is now ~45 years old. Progress in the practical aspects of alkyne metathesis reactions with well-defined complexes, as well as applications, in the last decade, guarantees that it is destined to become a useful method for the synthesis of organic molecules.

The number of well-defined molybdenum and tungsten alkylidyne complexes that are able to catalyze alkyne metathesis reactions efficiently has been significantly expanded in recent years.The latest developments in this field featuring highly active imidazolin-2-iminato- and silanolate-alkylidyne complexes are outlined in this review.