Nickel tetracarbonyl

Nickel carbonyl
Nickel carbonyl
Nickel carbonyl (IUPAC name: tetracarbonylnickel) is the organonickel compound with the formula Ni(CO)4. This pale-yellow liquid is the principal carbonyl of nickel. It is an intermediate in the Mond process for the purification of nickel and a reagent in organometallic chemistry. Nickel carbonyl is one of the most toxic substances encountered in industrial processes.

In nickel tetracarbonyl, the oxidation state for nickel is assigned as zero. The formula conforms to 18-electron rule. The molecule is tetrahedral, with four carbonyl (carbon monoxide) ligands attached to nickel. The CO ligands, in which the C and the O are connected by triple bonds, are covalently bonded to the nickel atom via the carbon ends. Electron diffraction studies have been performed on this molecule, and the Ni–C and C–O distances have been calculated to be 1.838(2) and 1.141(2) angstroms respectively.

Ni(CO)4 was first synthesised in 1890 by Ludwig Mond by the direct reaction of nickel metal with CO. This pioneering work foreshadowed the existence of many other metal carbonyl compounds, including those of V, Cr, Mn, Fe, and Co. It was also applied industrially to the purification of nickel by the end of the 19th century.

At 323 K (50 °C; 122 °F), carbon monoxide is passed over impure nickel. The optimal rate occurs at 130 °C.

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.

This page was last edited on 18 February 2018, at 20:55.
Reference: under CC BY-SA license.

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