Bis(cyclooctadiene)nickel(0) is the organonickel compound with the formula Ni(C₈H₁₂)₂, also written Ni(cod)₂. It is a diamagnetic

coordination complex A coordination complex consists of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of bound molecules or ions, that are in turn known as ''ligands'' or complexing agents. Many ...

featuring tetrahedral nickel(0) bound to the alkene groups in two

1,5-cyclooctadiene Cycloocta-1,5-diene is a cyclic hydrocarbon with the chemical formula , specifically . There are three configurational isomers with this structure, that differ by the arrangement of the four C–C single bonds adjacent to the double bonds. Each ...

ligand In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electr ...

s. This highly air-sensitive yellow solid is a common source of Ni(0) in chemical synthesis.

Preparation and properties

The complex is prepared by reduction of anhydrous

nickel(II) acetylacetonate Nickel(II) bis(acetylacetonate) is a coordination complex with the formula i(acac)2sub>3, where acac is the anion C5H7O2− derived from deprotonation of acetylacetone. It is a dark green paramagnetic solid that is soluble in organic solvents suc ...

in the presence of the diolefin: :Ni(acac)₂ + 2 cod + 2 AlEt₃ → Ni(cod)₂ + 2 acacAlEt₂ + C₂H₆ + C₂H₄ Ni(cod)₂ is moderately soluble in several organic solvents. One or both

ligands are readily displaced by phosphines, phosphites,

bipyridine Bipyridines also known as bipyridyls, dipyridyls, and dipyridines, are a family of chemical compounds with the formula (C5H4N)2, consisting of two pyridyl (C5H4N) rings. Pyridine is an aromatic nitrogen-containing heterocycle. Bipyridines are of sig ...

, and

isocyanide An isocyanide (also called isonitrile or carbylamine) is an organic compound with the functional group –. It is the isomer of the related nitrile (–C≡N), hence the prefix is ''isocyano''.IUPAC Goldboo''isocyanides''/ref> The organic fragme ...

s. If exposed to air, the solid oxidizes to

nickel(II) oxide Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to r ...

. As a result, this compound is generally handled in a

glovebox A glovebox (or glove box) is a sealed container that is designed to allow one to manipulate objects where a separate atmosphere is desired. Built into the sides of the glovebox are gloves arranged in such a way that the user can place their han ...

References

{{Nickel compounds Organonickel compounds Cyclooctadiene complexes