Tris(acetylacetonato)cobalt(III) is the

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 ' ...

with the formula Co(C₅H₇O₂)₃. Often abbreviated Co(acac)₃, it is a green, diamagnetic solid that is soluble in organic solvents, but not in water. Owing to its solubility in organic solvents, tris(acetylacetonato)cobalt(III) is used to produce

homogeneous catalyst In chemistry, homogeneous catalysis is catalysis where the catalyst is in same phase as reactants, principally by a soluble catalyst in a solution. In contrast, heterogeneous catalysis describes processes where the catalysts and substrate are in di ...

s by reduction.

Structure

The structure of the complex has been confirmed by

X-ray crystallography X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...

. The three acac⁻ ligands bind in a bidentate fashion to cobalt, defining an octahedral complex. The solid is isomorphous with

tris(acetylacetonato)iron(III) Tris(acetylacetonato) iron(III), often abbreviated Fe(acac)3, is a ferric coordination complex featuring acetylacetonate (acac) ligands, making it one of a family of metal acetylacetonates. It is a red air-stable solid that dissolves in nonpol ...

, tris(acetylacetonato)manganese(III), and tris(acetylacetonato)aluminium. With D₃-symmetry, these complexes are

chiral Chirality () is a property of asymmetry important in several branches of science. The word ''chirality'' is derived from the Greek language, Greek (''kheir''), "hand", a familiar chiral object. An object or a system is ''chiral'' if it is dist ...

and often can be resolved into the individual enantiomers.

Synthesis and reactions

Tris(acetylacetonato)cobalt(III) is prepared by the reaction of

cobalt(II) carbonate Cobalt(II) carbonate is the inorganic compound with the formula CoCO3. This pink paramagnetic solid is an intermediate in the hydrometallurgical purification of cobalt from its ores. It is an inorganic pigment, and a precursor to catalysts. Coba ...

and

acetylacetone Acetylacetone is an organic compound with the chemical formula . It is classified as a 1,3-diketone. It exists in equilibrium with a tautomer . The mixture is a colorless liquid. These tautomers interconvert so rapidly under most conditions that ...

in the presence of

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscosity, viscous than Properties of water, water. It is used as an oxidizer, bleaching agent, and antiseptic, usua ...

: :2 CoCO₃ + 6 CH₃COCH₂COCH₃ + H₂O₂ → 2 Co(O₂C₃Me₂H)₃ + 2 CO₂ + 4 H₂O One distinctive aspect of Co(acac)₃ is its susceptibility toward

electrophilic aromatic substitution Electrophilic aromatic substitution (SEAr) is an organic reaction in which an atom that is attached to an aromatic ring, aromatic system (usually hydrogen) is replaced by an electrophile. Some of the most important electrophilic aromatic substitut ...

, by which protons on the central carbon are replaced with diverse electrophiles (Me =

methyl In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula (whereas normal methane has the formula ). In formulas, the group is often abbreviated as ...

): :Co(O₂C₃Me₂H)₃ + 3NO₂⁺ → Co(O₂C₃Me₂NO₂)₃ + 3H⁺

References

{{Acetylacetonate complexes Acetylacetonate complexes Cobalt complexes