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Other names
Cobalt(III) acetylacetonate, tris(acac) cobalt
3D model (JSmol)
ECHA InfoCard 100.040.464 Edit this at Wikidata
EC Number
  • 244-527-6
  • InChI=1S/3C5H8O2.Co/c3*1-4(6)3-5(2)7;/h3*3,6H,1-2H3;/q;;;+3/p-3/b3*4-3+;
  • C/C(=C\C(=O)C)/[O-].C/C(=C\C(=O)C)/[O-].C/C(=C\C(=O)C)/[O-].[Co+3]
Molar mass 356.260 g·mol−1
Appearance green solid
Density 1.41 g/cm3
Melting point 213 °C (415 °F; 486 K)
GHS labelling:
GHS07: Exclamation markGHS08: Health hazard
H302, H317, H334
P261, P264, P270, P272, P280, P285, P301+P312, P302+P352, P304+P341, P321, P330, P333+P313, P342+P311, P363, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Tris(acetylacetonato)cobalt(III) is the coordination complex 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 catalysts by reduction.[1]


The structure of the complex has been confirmed by X-ray crystallography. The three acac- ligands bind in a bidentate fashion to cobalt, defining an octahedral complex.[2] The solid is isomorphous with tris(acetylacetonato)iron(III), tris(acetylacetonato)manganese(III), and tris(acetylacetonato)aluminium. With D3-symmetry, these complexes are chiral and often can be resolved into the individual enantiomers.

Synthesis and reactions[edit]

Tris(acetylacetonato)cobalt(III) is prepared by the reaction of cobalt(II) carbonate and acetylacetone in the presence of hydrogen peroxide:[3]

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, by which protons on the central carbon are replaced with diverse electrophiles (Me = methyl):[4]

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


  1. ^ Mayo, Peter D.; Tam, William (2002). "Tris(acetoacetonyl)cobalt". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rn00084. ISBN 0471936235.
  2. ^ Arslan, Evrim; Lalancette, Roger A.; Bernal, Ivan (2017). "An Historic and Scientific Study of the Properties of Metal(III) Tris-acetylacetonates". Structural Chemistry. 28: 201–212. doi:10.1007/s11224-016-0864-0. S2CID 99668641.
  3. ^ Bryant, Burl E.; Fernelius, W. Conard (1957). "Cobalt(III) Acetylacetonate". Inorganic Syntheses. 5: 188–189. doi:10.1002/9780470132364.ch53. ISBN 9780470132364.
  4. ^ Shalhoub, George M. (1980). "Co(acac)3 Synthesis, Reactions, and Spectra: An Experiment for General Chemistry". Journal of Chemical Education. 57 (7): 525. Bibcode:1980JChEd..57..525S. doi:10.1021/ed057p525.