Tungsten hexacarbonyl

Tungsten hexacarbonyl

Names
IUPAC name Hexacarbonyltungsten
Other names Tungsten carbonyl Hexacarbonylwolfram
Identifiers
CAS Number	14040-11-0
EC Number	237-880-2
Jmol interactive 3D	Image
PubChem	98884
InChI InChI=1/6CO.W/c6*1-2;
SMILES [C-]#[O+].[C-]#[O+].[C-]#[O+].[C-]#[O+].[C-]#[O+].[C-]#[O+].[W]
Properties
Chemical formula	C6O6W
Molar mass	351.901 g/mol
Appearance	Colorless solid
Density	2.65 g/cm^3
Melting point	170 °C (338 °F; 443 K) (decomposes)
Solubility in water	insoluble
Solubility	sparingly in THF
Hazards
Main hazards	Flammable, CO source
Related compounds
Other cations	Chromium hexacarbonyl Molybdenum hexacarbonyl
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Tungsten hexacarbonyl (also called tungsten carbonyl) is the chemical compound with the formula W(CO)₆. This complex gave rise to the first example of a dihydrogen complex.^[1]

This colorless compound, like its chromium and molybdenum analogs, is noteworthy as a volatile, air-stable derivative of tungsten in its zero oxidation state.

Preparation, properties, and structure

W(CO)₆ is prepared by the reduction of WCl₆ under a pressure of carbon monoxide. It would be rare to prepare this inexpensive compound in the laboratory because the apparatus is expensive and the compound can be purchased cheaply. 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.^[2]

W(CO)₆ adopts an octahedral geometry consisting of six rod-like CO ligands radiating from the central W atom with dipole moment 0 D.

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.

One derivative is the dihydrogen complex W(CO)₃[P(C₆H₁₁)₃]₂(H₂) reported in 1982 by Kubas.^[1]

Three of these CO ligands can be displaced by acetonitrile.^[3] 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 dangerous source of volatile metal as well as CO.

References

1. Kubas, G. J., Metal Dihydrogen and σ-Bond Complexes, Kluwer Academic/Plenum Publishers: New York, 2001.
2. Randolph, S.; Fowlkes, J.; Rack, P. (2006). "Focused, Nanoscale Electron-Beam-Induced Deposition and Etching". Critical Reviews of Solid State and Materials Sciences 31 (3): 55. doi:10.1080/10408430600930438.
3. Kubas, G. J. and van der Sluys, L. S., "TricarbonylTris(nitrile) Complexes of Cr, Mo, and W", Inorganic Syntheses, 1990, 28, 29–33, doi:10.1002/9780470132593.ch6.