Bis(cyclooctadiene)nickel(0) is the
organonickel compound with the formula Ni(C
8H
12)
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. ...
featuring tetrahedral nickel(0) bound to the alkene groups in two
1,5-cyclooctadiene 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 elec ...
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 acacAlEt
2 + C
2H
6 + C
2H
4
Ni(cod)
2 is moderately soluble in several organic solvents. One or both
1,5-cyclooctadiene 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 si ...
, 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 hand ...
.
References
{{Nickel compounds
Organonickel compounds
Cyclooctadiene complexes