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 is a chemical compound consisting of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of chemical bond, bound molecules or ions, that are in turn known as ' ...

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

1,5-cyclooctadiene 1,5-Cyclooctadiene (also known as cycloocta-1,5-diene) is a cyclic compound, cyclic hydrocarbon with the chemical formula , specifically . There are three configurational isomers with this structure, that differ by the arrangement of the four C� ...

ligand In coordination chemistry, a ligand is an ion or molecule with a 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 el ...

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 derived from deprotonation of acetylacetone. It is a dark green paramagnetic solid that is soluble in organic solvents such as tolu ...

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. If exposed to air, the solid oxidizes in a few minutes to

nickel(II) oxide Nickel(II) oxide is the chemical compound with the formula . It is the principal oxide of nickel. It is classified as a basic metal oxide. Several million kilograms are produced annually of varying quality, mainly as an intermediate in the product ...

. 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 ...

Reactions

The reactivity of Ni(cod)₂ has been extensively examined. One or both

ligands are readily displaced by phosphines, phosphites,

bipyridine Bipyridines are a family of organic compounds with the formula (C5H4N)2, consisting of two pyridyl (C5H4N) rings. Pyridine is an aromatic nitrogen-containing heterocycle. The bipyridines are all colourless solids, which are soluble in organic sol ...

, 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. Oxidation gives the highly reactive monocation, which can be isolated when using

weakly coordinating anion Anions that interact weakly with cations are termed non-coordinating anions, although a more accurate term is weakly coordinating anion. Non-coordinating anions are useful in studying the reactivity of electrophilic cations. They are commonly found ...

s: : Of its many catalytic reactions, Ni(cod)₂ in the presence of phosphine ligands catalyzes the demethoxylation of

anisole Anisole, or methoxybenzene, is an organic compound with the formula . It is a colorless liquid with a smell reminiscent of anise seed, and in fact many of its derivatives are found in natural and artificial fragrances. The compound is mainly ...

s by

hydrosilane Hydrosilanes are tetravalent silicon compounds containing one or more Si-H bond. The parent hydrosilane is silane (SiH4). Commonly, hydrosilane refers to organosilicon derivatives. Examples include phenylsilane (PhSiH3) and triethoxysilane ((C2H ...

s: :

References

{{Nickel compounds Organonickel compounds Cyclooctadiene complexes