Syntheses and characterization of ammonium and tetraalkylammonium thiomolybdates and thiotungstates

McDonald, John W.; Friesen, Gabi; Rosenhein, Laurence D.; Newton, William E.

doi:10.1016/s0020-1693(00)81720-x

Cited by 457 publications

(199 citation statements)

References 13 publications

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“…This optical absorption spectrum shows two absorption peaks centered at ∼307 and 465 nm corresponding to the tetrathiomolybdate ions (MoS 4 2− ) [32,33]. Figure 2: XPS spectra (a) for Mo, after and before curve peak fitting, and (b) for S in the as-precipitated precursor sample obtained after acidification of ATM solution.…”

Section: Analysis Of the Precursor Precipitatementioning

confidence: 99%

Aqueous Medium Synthesis Route for Randomly Stacked Molybdenum Disulfide

Panigrahi

Pathak

2013

Journal of Nanoparticles

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Synthesis of poorly crystalline, randomly oriented rag-like structures of molybdenum disulfide has been reported starting from aqueous solutions of ammonium molybdate, and thioacetamide in presence of sodium dodecyl sulfate via calcination of the amorphous precipitates, obtained through acidification of the in situ generated intermediate of ammonium tetrathiomolybdate. X-ray photoelectron spectroscopy, UV-visible spectroscopy, and X-ray diffraction of the calcined samples reveal the formation of single-phase MoS 2 , while the amorphous precipitates have been found to be a mixture of Mo 2 S 5 , MoS 3 , and a trace amount of H 2 MoS 4 . Highly folded and disordered layers of rag-like MoS 2 have been confirmed through high-resolution transmission electron microscopy. The electrical conductivity for the cold pressed pellet of the MoS 2 sample is found to be significantly higher than that of 2H-MoS 2 and increases further on annealing.

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Section: Analysis Of the Precursor Precipitatementioning

confidence: 99%

Aqueous Medium Synthesis Route for Randomly Stacked Molybdenum Disulfide

Panigrahi

Pathak

2013

Journal of Nanoparticles

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“…(c) The 500-600-nm bands disappeared on further additions of air, concurrent with the development of spectral features at 465 nm and 390 nm and a steeply rising baseline in the 300 -400-nm range, probably due to Fe3+ formed on oxygenation. The peak at 390nm corresponds to the absorption maximum of [MoOS3I2 -, while the band at 465 nm could be due to a second maximum in the spectrum of [MoOS3I2-, a relatively small amount of [MoS4I2-, or a combination of these two possibilities [22]. Our efforts to quantify the thiomolybdates were hampered by the baseline problem, but about 75% of the molybdenum in the original sample could be accounted for if the bands were assumed to arise from [MoOS3I2-only.…”

Section: Decomposition Of Femocomentioning

confidence: 99%

Elicitation of thiomolybdates from the iron‐molybdenum cofactor of nitrogenase

Newton

Gheller

Hedman

et al. 1986

European Journal of Biochemistry

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Aerial oxidation of the iron-molybdenum cofactor (FeMoco) of Azotobacter vinelandii nitrogenase has been shown to yield either the tetrathiomolybdate ion ([MoS4I2-) or the oxotrithiomolybdate ion ([MoOS3l2-), depending on the reaction conditions. Thus, when N-methylformamide (NMF) solutions of FeMoco either were titrated with measured aliquots of air or were diluted with air-saturated NMF, [MoOS3I2-was found to be the predominant product while dilution of NMF solutions of FeMoco with air-saturated methanol produced [MoS4I2-almost exclusively. Similar aerial oxidation of solutions of chemically synthesized Fe-Mo-S clusters showed that significant information about the molybdenum environment in these species could be deduced from the nature of the elicited thiomolybdates. The differences in decomposition products as a function of solvent are postulated to be due to the loss through precipitation of the reducing agent sodium dithionite on addition of methanol but not NMF. These overall decomposition results are discussed in the context of recent X-ray absorption spectroscopic data which suggest the presence of an 'MoS3' core in FeMoco. A possible mechanism whereby [MoS4I2-might be rapidly formed from this core is presented.The iron-molybdenum cofactor (FeMoco) is the extruded, putative Nz-reducing site of nitrogenase [I], obtained by acid treatment of the molybdenum-iron protein of that enzyme followed by extraction with the organic solvent N-methylformamide (NMF) [2, 31. Nitrogenase contains two such cofactors, each of which accounts for one Mo and 6 -8 atoms of Fe and probably 8 -9 atoms of sulfur arranged in a cluster [2-41 so far unrecognized elsewhere in biology [3-91. Although numerous attempts have been made to simulate the structure and/or chemical properties of FeMoco via synthesis and study of Mo-Fe-S cluster compounds, a close chemical model of the site has remained elusive [lo-131. The most incisive structural information on FeMoco has come from Xray absorption spectroscopy (XAS), both near edge spectra (XANES) and fine structure analysis (EXAFS), with the recent data [14, 151 suggesting a molybdenum environment which is comprised of three 0 (or N) and three S atoms from anionic ligands. However, although EXAFS is very precise in identifying the type of donor atom and its distance from the absorber (Mo), it is very much less precise in defining the number of such atoms. Thus, in order to obtain independent, complementary insight into the nature of the molybdenum environment in FeMoco, especially with respect to the number of S donor atoms, we have carried out oxidative decomposition studies of this entity and herein report our results, which Correspondence to W. E.

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“…The first three absorption bands matched with those of the tetrathiotungstate ions (WS 2− 4 ) [30,33], which might have formed in the precursor solution through microwave-induced exchange reaction. This reaction may involve the successive [34].…”

Section: Resultsmentioning

confidence: 69%

“…Microwave irradiation facilitates instantaneous generation of the tetrathiotungstate precursors in solution, which in consequence makes the process of preparation of nanostructured WS 2 much faster and less cumbersome compared to the other reported chemical routes [30]. The developed process is technically simple and makes use of a domestic microwave oven.…”

Section: Introductionmentioning

confidence: 99%

Microwave-assisted synthesis of WS₂nanowires through tetrathiotungstate precursors

Panigrahi¹,

Pathak²

2008

Science and Technology of Advanced Materials

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Tungsten disulfide (WS 2 ) nanowires have been synthesized through a microwave-assisted chemical route that uses tungstic acid, elemental sulfur and monoethanolamine as starting reagents for obtaining a precursor solution of tetrathiotungstate ions. Acidification of the precursor solution yields amorphous precipitates, which lead to the formation of nanowires of WS 2 with thickness of about 5-10 nm when heated at 750• C under argon atmosphere for 1.5 h. Phase and the microstructure of the prepared powders have been investigated through x-ray powder diffraction and high-resolution transmission electron microscopy, respectively. Optical absorption of the WS 2 powders reveals a red shift of the exciton bands compared to bulk WS 2 .

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Syntheses and characterization of ammonium and tetraalkylammonium thiomolybdates and thiotungstates

Cited by 457 publications

References 13 publications

Aqueous Medium Synthesis Route for Randomly Stacked Molybdenum Disulfide

Aqueous Medium Synthesis Route for Randomly Stacked Molybdenum Disulfide

Elicitation of thiomolybdates from the iron‐molybdenum cofactor of nitrogenase

Microwave-assisted synthesis of WS₂nanowires through tetrathiotungstate precursors

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Syntheses and characterization of ammonium and tetraalkylammonium thiomolybdates and thiotungstates

Cited by 457 publications

References 13 publications

Aqueous Medium Synthesis Route for Randomly Stacked Molybdenum Disulfide

Aqueous Medium Synthesis Route for Randomly Stacked Molybdenum Disulfide

Elicitation of thiomolybdates from the iron‐molybdenum cofactor of nitrogenase

Microwave-assisted synthesis of WS2nanowires through tetrathiotungstate precursors

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Microwave-assisted synthesis of WS₂nanowires through tetrathiotungstate precursors