Chromium(III) acetylacetonate

Chromium(III) acetylacetonate[1]
Solid Chromium (III) acetylacetonate
Solid chromium(III) acetylacetonate
Names
IUPAC name
Chromium(III) acetylacetonate
Other names
Tris(2,4-pentanediono)chromium(III), Cr(acac)3, Cr(pd)3
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.040.463
EC Number 244-526-0
Properties
Cr(C5H7O2)3
Molar mass 349.32
Appearance deep maroon
Density 1.34 g/cm3
Melting point 210 °C (410 °F; 483 K)
Boiling point 340 °C (644 °F; 613 K) (sublimes near 100 °C)
Solubility in non-polar organic solvents soluble
Hazards
GHS pictograms
GHS signal word Warning
H315, H319, H335
P261, P264, P271, P280, P302+352, P304+340, P305+351+338, P312, P321, P332+313, P337+313, P362, P403+233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Chromium(III) acetylacetonate is the coordination compound with the formula Cr(C5H7O2)3, sometimes designated as Cr(acac)3. This purplish coordination complex is used in NMR spectroscopy as a relaxation agent because of its solubility in nonpolar organic solvents and its paramagnetism.

Synthesis and structure

The compound is prepared by the reaction of chromium(III) oxide with acetylacetone (Hacac):[2]

Cr2O3 + 6 Hacac → 2 Cr(acac)3 + 3 H2O

The complex has idealized D3 symmetry. The Cr-O distances are 1.93 Å.[3] The complex has been resolved into individual enantiomers by separation of its adduct with dibenzoyltartrate.[4]

Like many other Cr(III) compounds, it has a quartet ground state.

The complex is relatively inert toward substitution but undergoes bromination at the 3-positions of the chelate rings.

References

  1. ↑ Chromium acetylacetonate at American Elements
  2. ↑ W. Conard Fernelius, Julian E. Blanch “Chromium(III) Acetylacetonate: [Tris(2,4-Pentanediono)Chromium(III)]” Inorganic Syntheses, 1957, Volume 5, 130-131.doi:10.1002/9780470132364.ch35
  3. ↑ B. Morosin "The crystal structure of trisacetylacetonatochromium(III)" Acta Crystallogr. 1965. vol. 19, 131-137. doi:10.1107/S0365110X65002876
  4. ↑ Drake, A. F.; Gould, J. M.; Mason, S. F.; Rosini, C.; Woodley, F. J. (1983). "The optical resolution of tris(pentane-2,4-dionato)metal(III) complexes". Polyhedron. 2: 537–538. doi:10.1016/S0277-5387(00)87108-9.
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