Electronically-coupled MM quadruply-bonded complexes of molybdenum and tungsten.

Chemical record (New York, N.Y.) (2005-10-08)
Malcolm H Chisholm, Nathan J Patmore
RESUMO

The reaction of M2(O2CBu(t))4 (M = Mo, W) with a dicarboxylic acid in toluene yields compounds of general formula [M2]-O2C-X-CO2-[M2] ([M2] = M2(O2CBu(t))3; X = conjugated spacer). The M2 units are electronically coupled via interactions between the M2 delta and dicarboxylate pi* orbitals, and the magnitude of this coupling is revealed by electronic structure calculations and spectroscopic data. These compounds show intense metal to ligand charge transfer (MLCT) absorptions in the visible region of the electronic spectrum that are temperature and solvent dependent. Evidence of electronic coupling is seen in their cyclic voltammograms, which show two successive one-electron oxidations. The extent of electronic coupling in the mixed valence radical cations [M2]-O2C-X-CO2-[M2]+, generated by oxidation with one equivalent of AgPF6 or FeCp2PF6, is evaluated by EPR and UV-vis-NIR spectroscopic data, and delocalized behavior is observed in compounds with W2 units separated by up to 13.6 angstroms. The simplicity of the frontier M2 orbital interactions with the bridge pi orbitals provides a convenient system with which to study electron transfer in mixed valence systems, as compared to the extensively studied, but more complicated, dinuclear t(2g)6/t(2g)5 mixed valence compounds. Oligomeric and polymeric compounds incorporating M2 units have also been synthesized, having general formula [M2(O2CR)2(O2C-Thio-CO2)]n (Thio = n-hexyl substituted ter- and quinque-thiophenes). They can be deposited as thin films by spin coating, and show photoluminescence and electroluminescence. These metallo-polythiophenes show potential for application in electronic materials. (

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Sigma-Aldrich
Tungsten, powder, 12 μm, 99.9% trace metals basis
Sigma-Aldrich
Tungsten, wire, diam. 0.25 mm, ≥99.9% trace metals basis
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Tungsten, foil, thickness 0.05 mm, ≥99.9% trace metals basis
Sigma-Aldrich
Tungsten, wire, diam. 1.0 mm, 99.99% trace metals basis
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Tungsten, wire, diam. 0.5 mm, ≥99.9% trace metals basis
Sigma-Aldrich
Tungsten, foil, thickness 0.127 mm, ≥99.9% trace metals basis
Sigma-Aldrich
Tungsten, foil, thickness 0.25 mm, ≥99.9% trace metals basis
Tungsten, rod, 100mm, diameter 6.35mm, centerless ground, 99.95%
Sigma-Aldrich
Tungsten, foil, thickness 0.5 mm, ≥99.9% trace metals basis
Tungsten, wire reel, 25m, diameter 0.1mm, clean, 99.95%
Tungsten, wire reel, 5m, diameter 0.005mm, gold plated, 99.95%
Tungsten, wire reel, 25m, diameter 0.025mm, clean, 99.95%
Tungsten, wire reel, 10m, diameter 0.3mm, clean, 99.95%
Tungsten, wire, straight, 300mm, diameter 0.10mm, 99.9+%
Tungsten, wire, straight, 300mm, diameter 0.075mm, 99.9+%
Tungsten, wire reel, 100m, diameter 0.025mm, clean, 99.95%
Tungsten, insulated wire, 2m, conductor diameter 0.025mm, insulation thickness 0.005mm, polyimide insulation, 99.9%
Tungsten, wire reel, 1m, diameter 0.125mm, gold plated, 99.95%
Tungsten, wire reel, 10m, diameter 0.035mm, clean, 99.95%
Tungsten, wire reel, 10m, diameter 0.025mm, clean, 99.95%
Tungsten, foil, 100x100mm, thickness 0.125mm, as rolled, 99.95%
Tungsten, foil, 100x100mm, thickness 0.15mm, as rolled, 99.95%
Tungsten, foil, 100x100mm, thickness 0.1mm, as rolled, 99.95%
Tungsten, foil, 100x100mm, thickness 0.2mm, as rolled, 99.95%
Tungsten, foil, 100x100mm, thickness 0.3mm, as rolled, 99.95%
Tungsten, foil, 100x100mm, thickness 0.5mm, as rolled, 99.95%
Tungsten, foil, 100x100mm, thickness 1.0mm, as rolled, 99.95%
Tungsten, foil, 100x100mm, thickness 2.0mm, as rolled, 99.95%
Tungsten, foil, 150x150mm, thickness 0.125mm, as rolled, 99.95%
Tungsten, foil, 150x150mm, thickness 0.15mm, as rolled, 99.95%

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