Tungsten hexacarbonyl

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]

Tungsten hexacarbonyl

Names
IUPAC name Hexacarbonyltungsten
Other names Tungsten carbonyl Hexacarbonylwolfram
Identifiers
CAS Number	14040-11-0 Y
3D model (JSmol)	Interactive image
ChemSpider	89313
ECHA InfoCard	100.034.423
EC Number	237-880-2
PubChem CID	98884
CompTox Dashboard (EPA)	DTXSID20895051
InChI InChI=1/6CO.W/c6*1-2; Key: FQNHWXHRAUXLFU-UHFFFAOYSA-N
SMILES O=C=[W](=C=O)(=C=O)(=C=O)(=C=O)=C=O
Properties
Chemical formula	C6O6W
Molar mass	351.901 g/mol
Appearance	Colorless solid
Density	2.65 g/cm3
Melting point	170 °C (338 °F; 443 K) (decomposes)
Solubility in water	insoluble
Solubility	sparingly in THF
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Flammable, CO source
Hazards
NFPA 704 (fire diamond)	2 0 0
Safety data sheet (SDS)	External SDS
Related compounds
Other cations	Chromium hexacarbonyl Molybdenum hexacarbonyl Seaborgium hexacarbonyl[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

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.

Cyclopentadienyltungsten tricarbonyl dimer ((C₅H₅.)₂W₂(CO)₆) is produced from W(CO)₆.

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.