Tungsten hexacarbonyl
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| Template:Longitem | C6O6W |
| Molar mass | 351.901 g/mol |
| Appearance | Colorless solid |
| Density | 2.65 g/cm3 |
| Melting point | Template:Chembox CalcTemperatures |
| Solubility | sparingly in THF |
| Template:Longitem | Chromium hexacarbonyl Molybdenum hexacarbonyl |
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Tungsten hexacarbonyl (also called tungsten carbonyl) is an organometallic compound with the formula W(CO)6. This complex gave rise to the first example of a dihydrogen complex.[2]
Like its chromium and molybdenum analogs, this colorless compound is noteworthy as a volatile, air-stable derivative of tungsten in its zero oxidation state.
Preparation, properties, and structure
Like many metal carbonyls, W(CO)6 is generally prepared by "reductive carbonylation", which involves the reduction of a metal halide with under an atmosphere of carbon monoxide. As described in a 2023 survey of methods "most cost-effective routes for the synthesis of group 6 hexacarbonyls are based on the reduction of the metal chlorides (CrCl3, MoCl5 or WCl6) with magnesium, zinc or aluminium powders... under CO pressures".[3]Another means of preparation involves heating iron pentacarbonyl and WCl6, resulting in the formation of ferrous chloride.[4] The compound is relatively air-stable. It is sparingly soluble in nonpolar organic solvents. Tungsten carbonyl is widely used in electron beam-induced deposition technique - it is easily vaporized and decomposed by the electron beam providing a convenient source of tungsten atoms.[5]
W(CO)6 adopts an octahedral geometry consisting of six rod-like CO ligands radiating from the central W atom with dipole moment 0 debye.
Reactivity
All reactions of W(CO)6 commence with displacement of some CO ligands in W(CO)6. W(CO)6 behaves similarly to the Mo(CO)6 but tends to form compounds that are kinetically more robust.
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Treatment of tungsten hexacarbonyl with sodium cyclopentadienide followed by oxidation of the resulting NaW(CO)3(C5H5) gives cyclopentadienyltungsten tricarbonyl dimer.[6]
One derivative is the dihydrogen complex W(CO)3[P(C6H11)3]2(H2).[2]
Three of these CO ligands can be displaced by acetonitrile.[7] W(CO)6 has been used to desulfurize organosulfur compounds and as a precursor to catalysts for alkene metathesis.
Safety and handling
Like all metal carbonyls, W(CO)6 is a dangerous source of volatile metal as well as CO.
References
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- ↑ a b Kubas, G. J., Metal Dihydrogen and σ-Bond Complexes, Kluwer Academic/Plenum Publishers: New York, 2001
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