Molybdenum hexacarbonyl
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| Sample of molybdenum hexacarbonyl | |||
| Names | |||
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| IUPAC name
Hexacarbonylmolybdenum(0)
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| Systematic IUPAC name
Hexacarbonylmolybdenum[1]
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| Identifiers | |||
13939-06-5  |
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| ChEBI | CHEBI:30508  |
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| ChemSpider | 21428397 |
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| EC Number | 237-713-3 | ||
| 3798, 562210 | |||
| Jmol 3D model | Interactive image | ||
| MeSH | Hexacarbonylmolybdenum | ||
| PubChem | 98885 | ||
| UN number | 3466 | ||
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| Properties | |||
| C6MoO6 | |||
| Molar mass | 264.01 g·mol−1 | ||
| Appearance | Vivid, white, translucent crystals | ||
| Density | 1.96 g cm−3 | ||
| Melting point | 150 °C (302 °F; 423 K) | ||
| Boiling point | 156 °C (313 °F; 429 K) | ||
| Structure | |||
| Orthogonal | |||
| Octahedral | |||
| 0 D | |||
| Thermochemistry | |||
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Std enthalpy of
formation (ΔfH |
−989.1 kJ mol−1 | ||
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Std enthalpy of
combustion (ΔcH |
−2123.4 kJ mol−1 | ||
| Vapor pressure | {{{value}}} | ||
| Related compounds | |||
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Related compounds
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Chromium hexacarbonyl |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 verify (what is ?) |
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| Infobox references | |||
Molybdenum hexacarbonyl (also called molybdenum carbonyl) is the chemical compound with the formula Mo(CO)6. This colorless solid, like its chromium and tungsten analogues, is noteworthy as a volatile, air-stable derivative of a metal in its zero oxidation state.
Contents
Structure and properties
Mo(CO)6 adopts an octahedral geometry consisting of six rod-like CO ligands radiating from the central Mo atom. A recurring minor debate in some chemical circles concerns the definition of an "organometallic" compound. Usually, organometallic indicates the presence of a metal directly bonded via a M–C bond to an organic fragment, which must in turn have a C–H bond. By this strict definition, Mo(CO)6 is not organometallic.[citation needed]
Preparation
Mo(CO)6 is prepared by the reduction of molybdenum chlorides or oxides under a pressure of carbon monoxide,[citation needed] although it would be unusual to prepare this inexpensive compound in the laboratory. The compound is somewhat air-stable and sparingly soluble in nonpolar organic solvents.
Occurrence
Mo(CO)6 has been detected in landfills and sewage plants, the reducing, anaerobic environment being conducive to formation of Mo(CO)6.[2]
Applications in inorganic and organometallic synthesis
Molybdenum hexacarbonyl is widely used in electron beam-induced deposition technique - it is easily vaporized and decomposed by the electron beam providing a convenient source of molybdenum atoms.[3] Mo(CO)6 is also a popular reagent in organometallic synthesis[4] because one or more CO ligands can be displaced by other donor ligands.[5] For example, Mo(CO)6 reacts with 2,2′-bipyridine to afford Mo(CO)4(bipy). UV-photolysis of a THF solution of Mo(CO)6 gives Mo(CO)5(THF). Many metal carbonyls are similarly photo-activatable.
[Mo(CO)4(piperidine)2]
The thermal reaction of Mo(CO)6 with piperidine affords Mo(CO)4(piperidine)2. The two piperidine ligands in this yellow-colored compound are labile, which allows other ligands to be introduced under mild conditions. For instance, the reaction of [Mo(CO)4(piperidine)2] with triphenyl phosphine in boiling dichloromethane (b.p. ca. 40 °C) gives cis-[Mo(CO)4(PPh3)2]. This cis- complex isomerizes in toluene to trans-[Mo(CO)4(PPh3)2].[6]
[Mo(CO)3(MeCN)3]
Upon refluxing in a solution of acetonitrile, Mo(CO)6 converts to its tris(acetonitrile) derivative. The resulting air-sensitive compound serves as a source of "Mo(CO)3". For instance treatment with allyl chloride gives [MoCl(allyl)(CO)2(MeCN)2], whereas treatment with KTp and sodium cyclopentadienide gives [MoTp(CO)3]− and [MoCp(CO)3]− anions respectively. These anions can be reacted with electrophiles to form a wide range of products.[7]
Applications in organic synthesis
Mo(CO)6, [Mo(CO)3(MeCN)3], and related derivatives are employed as catalysts in organic synthesis. For example, these catalysts can be used for alkyne metathesis and the Pauson–Khand reaction.
Safety and handling
Like all metal carbonyls, Mo(CO)6 is dangerous source of volatile metal as well as CO. It diffuses readily into plastic stoppers.
References
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- ↑ http://www.chm.bris.ac.uk/teaching-labs/inorganic2ndyear/2004-2005labmanual/Experiment3.pdf Archived March 9, 2008 at the Wayback Machine
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
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Further reading
- Lua error in package.lua at line 80: module 'strict' not found.
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- Pages with broken file links
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- Articles with unsourced statements from May 2016
- Articles with unsourced statements from June 2009
- Molybdenum compounds
- Carbonyl complexes
- Octahedral compounds
