Bis(cyclooctadiene)nickel(0)
Bisnickel is the organonickel compound with the formula Ni2, also written Ni2. It is a diamagnetic coordination complex featuring tetrahedral nickel bound to the alkene groups in two 1,5-cyclooctadiene ligands. This highly air-sensitive yellow solid is a common source of Ni in chemical synthesis.
Preparation and properties
The complex is prepared by reduction of anhydrous nickel(II) acetylacetonate in the presence of the diolefin:Ni2 is moderately soluble in several organic solvents.
If exposed to air, the solid oxidizes in a few minutes to nickel(II) oxide. As a result, this compound is generally handled in a glovebox.
Reactions
The reactivity of Ni2 has been extensively examined. One or both 1,5-cyclooctadiene ligands are readily displaced by phosphines, phosphites, bipyridine, and isocyanides.Oxidation gives the highly reactive monocation, which can be isolated when using weakly coordinating anions:
Of its many catalytic reactions, Ni2 in the presence of phosphine ligands catalyzes the demethoxylation of anisoles by hydrosilanes: