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Rhodium(II) acetate

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Rhodium (II) Acetate
Rhodium(II) acetate
Names
IUPAC name Rhodium (II) acetate
Other names Dirhodium tetraacetate,
Tetrakis(acetato)dirhodium(II),
Rhodium diacetate dimer,
Tetrakis-(mu-acetato)dirhodium
Identifiers
CAS Number
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.036.425 Edit this at Wikidata
PubChem CID
RTECS number
  • VI9361000
CompTox Dashboard (EPA)
InChI
  • InChI=1S/2C2H4O2.Rh/c2*1-2(3)4;/h2*1H3,(H,3,4);/q;;+2/p-2Key: ITDJKCJYYAQMRO-UHFFFAOYSA-L
  • InChI=1/2C2H4O2.Rh/c2*1-2(3)4;/h2*1H3,(H,3,4);/q;;+2/p-2Key: ITDJKCJYYAQMRO-NUQVWONBAE
SMILES
  • .C(=O)C.C(=O)C
Properties
Chemical formula C8H12O8Rh2
Molar mass 441.99 g/mol
Appearance Emerald green powder
Density 1.126 g/cm
Melting point >100 °C
Boiling point decomposes
Solubility in water soluble
Solubility in other solvents polar organic solvents
Structure
Crystal structure monoclinic
Coordination geometry octahedral
Dipole moment 0 D
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
3 0 0
Flash point low flammability
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). checkverify (what is  ?) Infobox references
Chemical compound

Rhodium(II) acetate is the chemical compound with the formula Rh2(AcO)4, where AcO is the acetate ion (CH3CO2). This emerald green powder is a catalyst for cyclopropanation of alkenes. It is also used as catalyst for insertion into C-H and X-H bonds (X = N/S/O) and for ylide formation for organic syntheses.

Preparation

Rhodium(II) acetate is usually prepared by the heating hydrated rhodium(III) chloride in acetic acid (CH3COOH): Rhodium(II) acetate dimer undergoes ligand exchange, the replacement of the acetate group by other carboxylates and related groups.

Rh2(OAc)4 + 4 HO2Y → Rh2(O2Y)4 + 4 HOAc

Structure and Properties

The dinuclear structure of hydrated rhodium(II) acetate

The structure of rhodium(II) acetate features a pair of rhodium atoms, each with octahedral molecular geometry, defined by four acetate oxygen atoms, a water ligand, and a Rh-Rh bond (2.39 Å.. Copper(II) acetate and chromium(II) acetate adopt similar structures.

Chemical Properties

The application of dirhodium tetraacetate to organic synthesis was pioneered by Teyssie and co-workers. A extensive library of successful transformations rapidly evolved, ranging from Rh(II)-catalyzed OH and NH insertions to cyclopropanation of olefins and aromatic systems. Nowadays, it is used mainly as a catalyst. It can help distinguish between ribonucleosides and deoxynucleosides by binding selectively to ribonucleosides at their 2' and 3' OH groups. Rhodium(II) acetate dimer, compared to copper(II) acetate, is more reactive and useful in differentiating ribonucleosides and deoxynucleosides because it is soluble in aqueous solution like water whereas copper(II) acetate only dissolves in non-aqueous solution.

Selected catalytic reactions

1. Cyclopropanation

cyclopropanation
through the decomposition of diazocarbonyl compounds, the intra- and intermolecular cyclopropanation reactions occurs.

2. Aromatic cycloaddition

Aromatic cycloadditon
Rhodium acetate is a very efficient catalyst for two-component cycloaddition as well as three-component 1,3-dipolar cycloaddition reactions.

3. C-H insertion

C-H insertion
Rh(II)-catalyzed regioselective intramolecular and regiospecific intermolecular C-H insertion into aliphatic and aromatic C-H bonds is a useful method for the synthesis of a diverse range of organic compounds.

4. Oxidation of alcohols

oxidation of alcohols
Allylic and benzylic alcohols were oxidized to the corresponding carbonyl compounds using tert-butyl hydroperoxide in stoichiometric amounts and Rh2(OAc)4 as catalyst in dichloromethane at ambient temperature.

5. X-H insertion (X = N/S/O)

N-H insertion
Rh(II) carbenoid reacts with amines, alcohols or thiols to yield the product of a formal intra- or intermolecular X-H bond (X = N/O/S) insertion via the formation of an ylide intermediate.

References

  1. Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1002/9780470132449.ch16, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1002/9780470132449.ch16 instead.
  2. Doyle, M.P. (2000). "Asymmetric Addition and Insertion Reactions of Catalytically-Generated Metal Carbenes". In Ojima, Iwao (ed.). Catalytic Asymmetric Synthesis (2nd ed.). New York: Wiley. ISBN 0471298050. {{cite book}}: Cite has empty unknown parameter: |1= (help)
  3. Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1107/S0567740871004527, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1107/S0567740871004527 instead.
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  7. Template:Broken doi
Rhodium compounds
Rh(0)
Organorhodium(0) compounds
Rh(I)
Organorhodium(I) compounds
Rh(II)
Organorhodium(II) compunds
Rh(III)
Organorhodium(III) compunds
  • ((CH3)5C5RhCl2)2
  • Rh(O2C5H7)3
  • Rh(IV)
    Rh(V)
    Rh(VI)
    Categories: