The Coordination and Bioinorganic Chemistry of Molybdenum
09 Mar 2007-pp 1-223
About: The article was published on 2007-03-09. It has received 78 citations till now. The article focuses on the topics: Bioorganometallic chemistry & Bioinorganic chemistry.
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TL;DR: The 2011 WHO Guidelines for Drinking-Water Quality (fourth edition) advised a health-based value of 70μg/L for Mo but this is no longer promulgated as a formal guideline value as WHO consider such concentrations to be rarely found in drinking water as discussed by the authors.
196 citations
TL;DR: An overview of the current state of our understanding of the molybdenum-containing enzyme xanthine oxidoreductase is presented, with an emphasis on work done in the past five years.
Abstract: An overview of the current state of our understanding of the reaction mechanism of the molybdenum-containing enzyme xanthine oxidoreductase is presented, with an emphasis on work done in the past five years Recent studies of the biosynthesis of the pterin cofactor bound to the metal in the active site are also reviewed, as is crystallographic work that has clarified the coordination geometry of the molybdenum center This structural work provides the context in which to understand recent mechanistic studies of the enzyme, in particular those aimed at elucidating the role of specific amino acid residues in the active site of the enzyme(© Wiley-VCH Verlag GmbH & Co KGaA, 69451 Weinheim, Germany, 2006)
119 citations
TL;DR: In this article, synthetic aspects of molybdenum sulfide-based materials were reviewed, with emphasis on the catalytic materials, and a number of preparation methods were critically compared, including molecular precursor decomposition, hydrothermal, soft chemistry aqueous, surfactant-aided, intercalation-exfoliation, and solid gas reactions.
114 citations
TL;DR: The ability of Desulfovibrio desulfuricans formate dehydrogenase (DdFDH) to reduce carbon dioxide was kinetically and mechanistically characterized and a kinetic model of a hysteretic enzyme is proposed to interpret and predict the progress curves of the Dd FDH-catalyzed reactions.
Abstract: Carbon dioxide accumulation is a major concern for the ecosystems, but its abundance and low cost make it an interesting source for the production of chemical feedstocks and fuels. However, the thermodynamic and kinetic stability of the carbon dioxide molecule makes its activation a challenging task. Studying the chemistry used by nature to functionalize carbon dioxide should be helpful for the development of new efficient (bio)catalysts for atmospheric carbon dioxide utilization. In this work, the ability of Desulfovibrio desulfuricans formate dehydrogenase (Dd FDH) to reduce carbon dioxide was kinetically and mechanistically characterized. The Dd FDH is suggested to be purified in an inactive form that has to be activated through a reduction-dependent mechanism. A kinetic model of a hysteretic enzyme is proposed to interpret and predict the progress curves of the Dd FDH-catalyzed reactions (initial lag phase and subsequent faster phase). Once activated, Dd FDH is able to efficiently catalyze, not only t...
103 citations
TL;DR: The mesoporous molecular sieve MCM-41 was covalently grafted with 3-aminopropyl trimethoxysilane (AmpMCM41) in this article.
Abstract: The mesoporous molecular sieve MCM-41 was covalently grafted with 3-aminopropyl trimethoxysilane to give aminopropyl modified MCM-41 (AmpMCM-41). Reaction of this material with furfural, pyrrolcarbaldehyde, 2-acetylpyrrol, 2-aminoacetophenone, salicylaldehyde and acetylacetone afforded the corresponding supported Schiff base ligands. Subsequent reaction with bis(acetylacetonato)dioxomolybdenum(VI) leads to various molybdenum complexes supported on MCM-41 through propyl chain spacer. Characterization of these materials was carried out with FT-IR, atomic absorption spectroscopy, powder X-ray diffraction (XRD) and BET nitrogen adsorption–desorption methods. The XRD and BET analyses revealed that textural properties of support were preserved during the grafting experiments. The resultant materials successfully catalyzed the epoxidation of cyclooctene, cyclohexene, 1-hexene and 1-octene with tert -butyl hydroperoxide (TBHP) to the corresponding epoxides with 98–100% selectivities.
92 citations
References
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TL;DR: In this paper, the site-symmetrie Cs bzw. Ci and C1 were shown to exist in the azide chlorides CrO2ClN3 and MoCl4(N3)2 respectively.
Abstract: CrO2Cl2 und MoCl5 reagieren mit ClN3 unter Bildung der isolierbaren Azidchloride CrO2ClN3 und MoCl4(N3)2. Die Monoazide MoCl5N3 (aus MoCl5) und WCl5N3 (aus WCl6) konnten dagegen nicht isoliert werden; sie zersetzen sich rasch unter Abspaltung von N2 und Cl2, wobei die bisher unbekannten Nitridchloride MoNCl3 und WNCl3 entstehen. Ihre chemischen Eigenschaften, das magnetische Verhalten sowie die IR-Spektren werden beschrieben. Danach liegen Metall–Stickstoff-Dreifachbindungen vor (site-Symmetrie Cs bzw. Ci). Mit Pyridin bilden sich die Addukte MeNCl3 · 3 Py.
By reaction of CrO2Cl2 and MoCl5 with ClN3 the azide chlorides CrO2ClN3 and MoCl4(N3)2 respectively, were isolated. The monoazides MoCl5N3 (from MoCl5) and WCl5N3 (from WCl6) cannot be obtained; they splitt off N2 and Cl2; this reaction leads to the unknown nitride chlorides MoNCl3 and WNCl3. The chemical properties, the magnetic behaviour, and the IR spectra are discussed. This leads to the conclusion, that metal-nitrogen triple bonds exist in these compounds (site symmetry Cs and C1 respectively). With pyridine, the addition compounds MeNCl3 · 3 Py are formed.
52 citations
TL;DR: The current molybdothiol model systems were expanded to include ferredoxin-type complexes as electron-transfer catalysts, which provided new catalytically active systems containing molybdenum, iron, labile sulfide, and RSH components in proportions similarmore to that observed in native nitrogenase.
Abstract: Nitrogenase model systems composed of molybdate and thiol ligands such as L(+)-cysteine reduce molecular nitrogen to ammonia slowly in the presence of NaBH/sub 4/ as the reducing agent. In the presence of substrate amounts of ATP, the reduction of nitrogen is significantly stimulated but leads to the accumulation of diimide in the reaction solutions. The diimide decomposes or disproportionates to nitrogen, hydrogen, and hydrazine and is not reduced as such. The ammonia produced in all reactions arises primarily from the reduction of hydrazine. These observations were confirmed by independent experiments with diimide generated by the decomposition of azodicarboxylate and with hydrazine. Diimide is not a substrate for molybdothiol catalyst systems, while hydrazine is catalytically reduced to ammonia. Molybdothiol catalysts promote D/sub 2/-- H/ sup +/ exchange most efficiently in the presence of nitrogen as the substrate; they thus parallel nitrogenase also in this respect. The D/sub 2/-H/sup +/ exchange reaction is prssumably linked to the formation and decomposition of diimide in both the nitrogerase enzyme and its models. The current molybdothiol model systems were furthermore expanded to include ferredoxin-type complexes as electron-transfer catalysts. This provided new catalytically active systems containing molybdenum, iron, labile sulfide, and RSH components in proportions similarmore » to that observed in native nitrogenase. The new model systems catalyze the reduction of, e.g., acetylene efficiently even with S/sub 2/O/sub 4/ as the reducing agent and thus duplicate nitrogenase in yet another important respect. (12 tables, 6 figures) (auth)« less
51 citations
51 citations
51 citations