Chromium(III) acetylacetonate

Chromium(III) acetylacetonate

IUPAC name Chromium(III) acetylacetonate
Other names tris(2,4-pentanediono)chromium(III)
Identifiers
CAS number	21679-31-2^Y
ChemSpider	2006256^Y
ChEBI	CHEBI:33035^Y
Jmol-3D images	Image 1
SMILES [Cr+3].O=C([CH-]C(=O)C)C.O=C([CH-]C(=O)C)C.O=C([CH-]C(=O)C)C
InChI InChI=1S/3C5H7O2.Cr/c31-4(6)3-5(2)7;/h33H,1-2H3;/q3-1;+3^Y Key: GMJCSPGGZSWVKI-UHFFFAOYSA-N^Y InChI=1/3C5H7O2.Cr/c31-4(6)3-5(2)7;/h33H,1-2H3;/q3-1;+3 Key: GMJCSPGGZSWVKI-UHFFFAOYAF
Properties
Molecular formula	C₁₅H₂₁CrO₆
Molar mass	349.32
Appearance	deep maroon
Density	1.34 g/cm³
Melting point	216 °C
Boiling point	340 °C (sublimes near 100 °C)
Solubility in non-polar organic solvents	soluble
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
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):^[1]

Cr₂O₃ + 6 Hacac → 2 Cr(acac)₃ + 3 H₂O

The complex has idealized D₃ symmetry. Like other Cr(III) compounds, it has the d³ configuration, having a quartet ground state. Although it is relatively inert toward substitution, the complex undergoes bromination at the 3-positions of the chelate rings.

References

^ 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