Tris(acetylacetonato)iron(III), often abbreviated Fe(acac)<sub>3</sub>, 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 nonpolar organic solvents.
Fe(acac)<sub>3</sub> is prepared by treating freshly precipitated Fe(OH)<sub>3</sub> with acetylacetone.
Fe(acac)<sub>3</sub> is an octahedral complex with six equivalent Fe-O bonds with bond distances of about 2.00 à. The regular geometry is consistent with a high-spin Fe<sup>3+</sup> core with sp3d2 hybridization. As the metal orbitals are all evenly occupied the complex is not subject to Jahn-Teller distortions and thus adopts a D<sub>3</sub> molecular symmetry. In contrast, the related metal acetylacetonate Mn(acac)<sub>3</sub> adopts a more distorted octahedral structure. The 5 unpaired d-electrons also result in the complex being paramagnetic, with a magnetic moment of 5.90 ü<sub>B</sub>.
Fe(acac)<sub>3</sub> possesses helical chirality. The ÃÂ- and ÃÂ-enantiomers slowly inter-convert via Bailar and RayâÂÂDutt twists. The rate of interconversion is sufficiently slow to allow its enantiomers to be partially resolved.
Fe(acac)<sub>3</sub> has been examined as a precatalyst and reagent in organic chemistry, although the active iron-containing species is usually unidentified in these processes. In one instance, Fe(acac)<sub>3</sub> was shown to promote cross-coupling a diene to an olefin. Fe(acac)<sub>3</sub> catalyzes the dimerization of isoprene to a mixture of 1,5-dimethyl-1,5-cyclooctadiene and 2,5-dimethyl-1,5-cyclooctadiene.
Fe(acac)<sub>3</sub> also catalyzes the ring-opening polymerization of 1,3-benzoxazine. Beyond the area of polymerization, Fe(acac)<sub>3</sub> has been found to catalyze the reaction of N-sulfonyl oxaziridines with olefins to form 1,3-oxazolidine products.