| Nickel tetracarbonyl | |
|---|---|
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| IUPAC name |
Tetracarbonylnickel
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| Other names | Nickel carbonyl |
| Identifiers | |
| CAS number | 13463-39-3  |
| PubChem | 26039 |
| EC number | 236-669-2 |
| UN number | 1259 |
| ChEBI | 30372 |
| RTECS number | QR6300000 |
| Properties | |
| Molecular formula | Ni(CO)4 |
| Molar mass | 170.73 g/mol |
| Appearance | colorless or very-pale-yellow liquid diamagnetic |
| Density | 1.319 g/cm3 |
| Melting point |
-17.2 °C, 256 K, 1 °F |
| Boiling point |
43 °C, 316 K, 109 °F |
| Solubility in water | .018 g/100 mL (10 °C) |
| Solubility | miscible in most organic
solvents soluble in nitric acid, aqua regia |
| Viscosity | 3.05 x 10-4 Pa s |
| Structure | |
| Coordination geometry |
Tetrahedral |
| Molecular shape | Tetrahedral |
| Dipole moment | zero |
| Thermochemistry | |
| Std enthalpy of formation ΔfH |
−632 kJ/mol |
| Std enthalpy
of combustion ΔcH |
−1180 kJ/mol |
| Standard molar entropy S |
320 J K−1 mol−1 |
| Hazards | |
| MSDS | ICSC 0064 |
| EU Index | 028-001-00-1 |
| EU classification | Flammable ('F) Carc. Cat. 3 Repr. Cat. 2 Very Toxic (T+) Dangerous for the environment (N) |
| R-phrases | R61, R11, R26, R40, R50/53 |
| S-phrases | S53, S45, S60, S61 |
| NFPA 704 |
3
4
3
|
| Flash point | 4 °C |
| Autoignition temperature |
60 °C |
| Explosive limits | 2–34% |
| Related compounds | |
| Related metal carbonyls | Iron
pentacarbonyl Dicobalt octacarbonyl |
 (what is this?) (verify)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Nickel carbonyl (IUPAC name: tetracarbonylnickel) is the organonickel compound with the chemical formula Ni(CO)4. This very-pale-yellow metal carbonyl is a reagent in organometallic chemistry. The toxicity of this compound is well renown because the compound is very volatile at room temperature. Nickel carbonyl is an intermediate in the Mond process for the purification of nickel.
Contents |
Having the molecular formula Ni(CO)4, nickel carbonyl is tetrahedral with four carbonyl (carbon monoxide) ligands in a tetrahedral arrangement. The CO ligands, in which the C and the O are connected by triple bonds (often depicted as double bonds), are covalently bonded to the nickel atom via the carbon ends. The structures of these compounds baffled chemists for many years, and most publications before 1950 depicted chains of CO chelated to the metal.
Nickel carbonyl has 18 valence electrons, like many other metal carbonyls such as iron pentacarbonyl and molybdenum hexacarbonyl. These metal carbonyls have symmetrical structures and are charge-neutral, resulting in their high volatility. In Ni(CO)4, the nickel atom has a formal oxidation number of zero.
Ni(CO)4 was first synthesised in 1890 by Ludwig Mond by the direct reaction of nickel metal with CO.[1] This pioneering work foreshadowed the existence of many other metal carbonyl compounds, including those of V, Cr, Mn, Fe, and Co.
At 323 K (50 °C (122 °F)), carbon monoxide is passed over impure nickel. The optimal rate occurs at 130 °C.[2]
Ni(CO)4 is not readily available commercially. It is conveniently generated in the laboratory by carbonylation of commercially available bis(cyclooctadiene)nickel(0).
On moderate heating, Ni(CO)4 decomposes to carbon monoxide and nickel metal. Combined with the easy formation from CO and even impure nickel, this decomposition is the basis for the Mond process for the purification of nickel. Thermal decomposition commences near 180 °C and increases at higher temperature[2]
Like other low-valent metal carbonyls, Ni(CO)4 is susceptible to attack by nucleophiles. Attack can occur at nickel center, resulting in displacement of CO ligands, or at CO. Thus, donor ligands such as triphenylphosphine react to give Ni(CO)3(PPh3) and Ni(CO)2(PPh3)2. bipy) and related ligands behave similarly.[3]
Treatment with hydroxides gives clusters such as [Ni5(CO)12]2− and [Ni6(CO)12]2−. These compounds can also be obtained by reduction of nickel carbonyl.
Thus, treatment of Ni(CO)4 with carbon nucleophiles (Nu−) results in acyl derivatives such as [Ni(CO)3C(O)Nu)]−.[4]
Nickel carbonyl can be oxidized. Chlorine oxidizes nickel carbonyl into NiCl2, releasing CO gas. Other halogens behave analogously. This reaction provides a convenient method for destroying unwanted portions of the toxic compound.
Reactions of Ni(CO)4 with alkyl and aryl halides often result in carbonylated organic products. Vinylic halides, such as PhCH=CHBr, are converted to the unsaturated esters upon treatment with Ni(CO)4 followed by sodium methoxide. Such reactions also probably proceed via oxidative addition. Allylic halides give the pi-allyl nickel compounds, such as (allyl)2Ni2Cl2:[5]
Ni(CO)4 is highly hazardous, much more so than implied by its CO content, reflecting the effects of the nickel if it were released in the body. Nickel carbonyl may be fatal if absorbed through the skin or more likely, inhaled due to its high volatility. Its LC50 for a 30-minute exposure has been estimated at 3 ppm, and the concentration that is immediately fatal to humans would be 30 ppm. Some subjects exposed to puffs up to 5 ppm described the odour as musty or sooty, but since the compound is so exceedingly toxic its smell provides no reliable warning against a potentially fatal exposure.[6] Historically, laboratories that used Ni(CO)4 would keep a canary in the lab as an indicator of nickel carbonyl toxicity, due to the higher sensitivity of birds to this toxin.
The vapours of Ni(CO)4 can autoignite.
Nickel carbonyl poisoning is characterized by a two-stage illness. The first consists of headaches and chest pain lasting a few hours, usually followed by a short remission. The second phase is a chemical pneumonitis which starts after typically 16 hours with symptoms of cough, breathlessness and extreme fatigue. These reach greatest severity after four days, possibly resulting in death from cardiorespiratory or renal failure. Convalescence is often extremely protracted, often complicated by exhaustion, depression and dyspnea on exertion. Permanent respiratory damage is unusual. The carcinogenicity of Ni(CO)4 is a matter of debate.
Nickel carbonyl vapor decomposes quickly in air, lasting only about a minute.[7]
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  | NIOSH Pocket Guide to Chemical Hazards - NIOSH Document: Pocket Guide to Chemical Hazards: Nickel carbonyl | CDC/NIOSH |
| | International Chemical Safety Card 0064 - ICSC 0064 - NICKEL CARBONYL |
| | National Pollutant Inventory - Nickel carbonyl fact sheet - National Pollutant Inventory Substance Profile |
| | NIST Standard Reference Database - NIST Chemistry WebBook |
| | DOI - Nickel; Clinical Toxicology - 37(2):Pages 239-258 - Informa Pharmaceutical Science |
| | DOI - ScienceDirect - Science of The Total Environment : Nickel carbonyl: toxicity and human health |
| | European Chemicals Bureau - Ex-European Chemicals Bureau. |
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