Ruthenium(III) acetylacetonate

Ruthenium(III) acetylacetonate is a coordination complex with the formula Ru(O₂C₅H₇)₃. O₂C₅H₇⁻ is the ligand called acetylacetonate. This compound exists as a dark red solid that is soluble in most organic solvents.^[3] It is used as a precursor to other compounds of ruthenium.

Ruthenium(III) acetylacetonate

Names
IUPAC name Tris(acetylacetonato)ruthenium(III)
Other names Ru(acac)3; Ruthenium(III) 2,4-Pentanedionate; Ruthenium(III) acetylacetonato, 2,4-pentanedione ruthenium(III)
Identifiers
CAS Number	14284-93-6 Y
3D model (JSmol)	Interactive image
ECHA InfoCard	100.034.705
EC Number	238-193-0
PubChem CID	16057901
CompTox Dashboard (EPA)	DTXSID10904287
InChI InChI=1S/3C5H8O2.Ru/c3*1-4(6)3-5(2)7;/h3*3H2,1-2H3; Key: GNHBILLJFGEMKL-UHFFFAOYSA-N
SMILES CC(=O)CC(=O)C.CC(=O)CC(=O)C.CC(=O)CC(=O)C.[Ru]
Properties
Chemical formula	(C5H7O2)3Ru
Molar mass	398.39 g/mol
Appearance	Dark red solid
Density	1.54 g/cm3[1]
Melting point	260 °C (500 °F; 533 K)
Solubility in water	insoluble in water
Solubility	soluble in most organic solvents
Hazards[2]
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H302, H315, H319, H335, H413
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Preparation

In 1914 tris(acetylacetonato)ruthenium(III) was first prepared by the reaction of ruthenium(III) chloride and acetylacetone in the presence of potassium bicarbonate.^[4] Since then, alternative synthetic routes have been examined, but the original procedure remains useful with minor variations:^[5]

RuCl₃•3H₂O + MeCOCH₂COMe → Ru(acac)₃ + 3 HCl + 3 H₂O

Structure and properties

This compound has idealized D₃ symmetry. Six oxygen atoms surround the central ruthenium atom in an octahedral arrangement. The average Ru-O bond length in Ru(acac)₃ is 2.00 Å.^[1] Because Ru(acac)₃ is low spin, there is one unpaired d electron, causing this compound to be paramagnetic. Ru(acac)₃ has a magnetic susceptibility, χ_M, of 3.032×10⁻⁶ cm³/mol with an effective magnetic moment, μ_eff, of 1.66 μ_B.^[6] As a solution in dimethylformamide, the compound oxidizes at 0.593 and reduces at -1.223 V vs the ferrocene/ferrocenium couple.^[7]

Reduction of Ru(acac)₃ in the presence of alkenes affords the related diolefin complexes. Typically, such reactions are conducted with zinc amalgam in moist tetrahydrofuran:^[8]

2 Ru(acac)₃ + 4 alkene + Zn → 2 Ru(acac)₂(alkene)₂ + Zn(acac)₂

The resulting compounds are rare examples of metal-alkene complexes that reversibly sustain oxidation:

Ru(acac)₂(alkene)₂ ⇌ [Ru(acac)₂(alkene)₂]⁺ + e⁻

The complex has been resolved into individual enantiomers by separation of its adduct with dibenzoyltartaric acid.^[9]

References

1. Chao, G.; Sime, R. L.; Sime, R. J. (1973). "Crystal and molecular structure of tris(acetylacetonato)ruthenium(III)". Acta Crystallographica B. 29 (12): 2845. doi:10.1107/S0567740873007636.
2. "C&L Inventory". echa.europa.eu.
3. R. C. Mehrotra, R. Bohra, and D.P. Gaur "Metal β-Diketonates and Allied Derivatives", 1st ed.; Academic Press inc.: New York, 1978. ISBN 0-12-488150-5.
4. Barbieri, G. A. (1914). "Systematic chemical investigations: ruthenium, rhodium, palladium". Atti Accad, Lincei. 23 (1): 334–40.
5. Gupta, A. (2000). "Improved synthesis and reactivity of tris(acetylacetonato)ruthenium(III)". Indian Journal of Chemistry, Section A. 39A (4): 457. ISSN 0376-4710.
6. Grobelny, R. (1966). "The absorption spectra and magnetic properties of the chelated compounds of Ru(III) with β-diketones". Journal of Inorganic and Nuclear Chemistry. 28 (11): 2715–2718. doi:10.1016/0022-1902(66)80398-6.
7. Paul Sharpe; N. George Alameddin; David E. Richardson (1994). "Alkyl Substituent Effects in the Redox Thermochemistry of Coordination Compounds: Oxidation and Reduction Energetics for Ruthenium Tris(β-diketonate) Complexes in Solution and the Gas Phase". Journal of the American Chemical Society. 116 (24): 11098–11108. doi:10.1021/ja00103a027.
8. Bennett, M. A.; Byrnes, Matthew J.; Kováčik, Ivan (2004). "The fragment bis(acetylacetonato)ruthenium: a meeting-point of coordination and organometallic chemistry". Journal of Organometallic Chemistry. 689 (24): 4463. doi:10.1016/j.jorganchem.2004.07.027.
9. 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 (6): 537–538. doi:10.1016/S0277-5387(00)87108-9.