Iron pentacarbonyl
Names | |
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IUPAC name
Pentacarbonyliron(0)
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Other names
Pentacarbonyl iron
Iron carbonyl | |
Identifiers | |
3D model (
JSmol ) |
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ChEBI | |
ChemSpider | |
ECHA InfoCard
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100.033.323 |
PubChem CID
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RTECS number
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UNII | |
UN number | 1994 |
CompTox Dashboard (EPA)
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Properties | |
Fe(CO)5 | |
Molar mass | 195.90 g/mol |
Appearance | straw-yellow to brilliant orange liquid |
Odor | musty |
Density | 1.453 g/cm3 |
Melting point | −21.0 °C (−5.8 °F; 252.2 K) |
Boiling point | 103 °C (217 °F; 376 K) |
Insoluble | |
Solubility | Soluble in organic solvents slightly soluble in alcohol insoluble in ammonia |
Vapor pressure | 40 mmHg (30.6 °C)[1] |
Refractive index (nD)
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1.5196 (20 °C) |
Structure | |
D3h | |
trigonal bipyramidal | |
trigonal bipyramidal | |
0 D | |
Hazards | |
Occupational safety and health (OHS/OSH): | |
Main hazards
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Very toxic, highly flammable |
GHS labelling: | |
NFPA 704 (fire diamond) | |
Flash point | −15 °C (5 °F; 258 K) |
49 °C (120 °F; 322 K) | |
Explosive limits
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3.7–12.5% |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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25 mg/kg (rat, oral) |
NIOSH (US health exposure limits): | |
PEL (Permissible)
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none[1] |
REL (Recommended)
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TWA 0.1 ppm (0.23 mg/m3) ST 0.2 ppm (0.45 mg/m3)[1] |
IDLH (Immediate danger) |
0.4 ppm[1] |
Safety data sheet (SDS) | ICSC 0168 |
Related compounds | |
Related compounds
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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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Iron pentacarbonyl, also known as iron carbonyl, is the
Properties
Iron pentacarbonyl is a
Fe(CO)5 exhibits a relatively low rate of interchange between the axial and equatorial CO groups via the Berry mechanism.[3] It is characterized by two intense νCO bands in the IR spectrum at 2034 and 2014 cm−1 (gas phase).[4]
Synthesis and other iron carbonyls
Fe(CO)5 is produced by the reaction of fine iron particles with carbon monoxide. The compound was described in a journal by Mond and Langer in 1891 as "a somewhat viscous liquid of a pale-yellow colour."[5] Samples were prepared by treatment of finely divided, oxide-free iron powder with carbon monoxide at room temperature.
Industrial synthesis of the compound requires relatively high temperatures and pressures (e.g. 175
Industrial production and use
The industrial production of this compound is somewhat similar to the Mond process in that the metal is treated with carbon monoxide to give a volatile gas. In the case of iron pentacarbonyl, the reaction is more sluggish. It is necessary to use iron sponge as the starting material, and harsher reaction conditions of 5–30 MPa of carbon monoxide and 150–200 °C. Similar to the Mond process, sulfur acts as a catalyst. The crude iron pentacarbonyl is purified by distillation. Ullmann's Encyclopedia of Industrial Chemistry reports that there are only three plants manufacturing pentacarbonyliron; BASF in Germany and GAF in Alabama have capacities of 9000 and 1500–2000 tonnes/year respectively.[7]
Most iron pentacarbonyl produced is decomposed on site to give pure
Reactions
Irradiation of Fe(CO)5 with UV produces Fe(CO)4, which captures a variety of ligands to give adducts. In the absence of trapping substrates, Fe2(CO)9 is produced.[8]
Many compounds are derived from Fe(CO)5 by substitution of CO by
Oxidation and reduction
Most metal carbonyls can be halogenated. Thus, treatment of Fe(CO)5 with iodine gives iron tetracarbonyl diiodide:
- Fe(CO)5 + I2 → Fe(CO)4I2 + CO
Reduction of Fe(CO)5 with Na gives Na2Fe(CO)4, "tetracarbonylferrate" also called Collman's reagent. The dianion is isoelectronic with Ni(CO)4 but highly nucleophilic.[11]
Acid-base reactions
Fe(CO)5 is not readily
Diene adducts
Dienes react with Fe(CO)5 to give (diene)Fe(CO)3, wherein two CO ligands have been replaced by two olefins. Many dienes undergo this reaction, notably
Fe(CO)5 reacts in dicyclopentadiene to form [Fe(C5H5)(CO)2]2, cyclopentadienyliron dicarbonyl dimer. This compound, called "Fp dimer" can be considered a hybrid of ferrocene and Fe(CO)5, although in terms of its reactivity, it resembles neither.
CO substitution reactions
Upon UV irradiation Fe(CO)5 absorbs light population and metal-to-CO charge transfer band inducing CO photolysis and generating singlet and triplet coordinatively unsaturated intermediate Fe(CO)4 with high quantum yield. Prolonged irradiation in gas phase may proceed to further CO detach until atomic Fe formation.
Other uses
In
Iron pentacarbonyl has been found to be a strong
Toxicity and hazards
Fe(CO)5 is toxic, which is of concern because of its volatility (vapour pressure: 21 millimetres of mercury (2.8 kPa) at 20 °C). If
The National Institute for Occupational Safety and Health has set a recommended exposure limit for iron pentacarbonyl at 0.1 ppm (0.23 mg/m3) over an eight-hour time-weighted average, and a short-term exposure limit at 0.2 ppm (0.45 mg/m3).[16]
References
- ^ a b c d NIOSH Pocket Guide to Chemical Hazards. "#0345". National Institute for Occupational Safety and Health (NIOSH).
- ISBN 9780471936237.
- .
- .
- ^ ISBN 9780323161299.
- ^ ISBN 978-3527306732.
- .
- )
- )
- ^ Finke, R. G.; Sorrell, T. N. "Nucleophilic Acylation with Disodium Tetracarbonylferrate: Methyl 7-Oxoheptanoate and Methyl 7-oxooctonoate". Organic Syntheses; Collected Volumes, vol. 6, p. 807.
- ^ Pettit, R.; Henery, J. "Cyclobutadieneiron Tricarbonyl". Organic Syntheses; Collected Volumes, vol. 6, p. 310.
- ^ Birch, A. J.; Chamberlain, K. B. "Tricarbonyl[(2,3,4,5-η)-2,4-Cyclohexadien-1-one]iron and Tricarbonyl[(1,2,3,4,5-η)-2-Methoxy-2,4-Cyclohexadien-1-yl]Iron(1+) Hexafluorophosphate(1−) from Anisole". Organic Syntheses; Collected Volumes, vol. 6, p. 996.
- ^ Kovarik, Bill (1994). Charles F. Kettering and the 1921 discovery of tetraethyl lead. Fuels & Lubricants Division Conference, Society of Automotive Engineers. Baltimore, Maryland: environmentalhistory.org.
- ^ Lask, G.; Wagner, H. Gg. (1962). "Influence of additives on the velocity of laminar flames". Eighth International Symposium on Combustion: 432–438.
- ^ "Iron pentacarbonyl (as Fe)". NIOSH Pocket Guide to Chemical Hazards. Centers for Disease Control and Prevention. April 4, 2011. Retrieved November 19, 2013.