Rhodium(II) acetate

Rhodium(II) acetate
Names
IUPAC name
Rhodium(II) acetate
Other names
Dirhodium tetraacetate,
Tetrakis(acetato)dirhodium(II),
Rhodium diacetate dimer,
Tetrakis(μ-acetato)dirhodium
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.036.425 Edit this at Wikidata
EC Number
  • 240-084-8
RTECS number
  • VI9361000
UNII
  • InChI=1S/2C2H4O2.Rh/c2*1-2(3)4;/h2*1H3,(H,3,4);/q;;+2/p-2 checkY
    Key: ITDJKCJYYAQMRO-UHFFFAOYSA-L checkY
  • InChI=1S/4C2H4O2.2Rh/c4*1-2(3)4;;/h4*1H3,(H,3,4);;/q;;;;2*+2/p-4
    Key: : SYBXSZMNKDOUCA-UHFFFAOYSA-J
  • [OH2][Rh+3]1234#[Rh+3]([OH2])(O[C-](C)O1)(O[C-](C)O2)(O[C-](C)O3)O[C-](C)O4
Properties
C8H12O8Rh2
Molar mass 441.99 g/mol
Appearance Emerald green powder
Density 1.126 g/cm3
Melting point >100 °C
Boiling point decomposes
soluble
Solubility in other solvents polar organic solvents
Structure
monoclinic
octahedral
0 D
Hazards
GHS labelling:[1]
GHS07: Exclamation mark
Warning
H315, H319
P264, P280, P302+P352, P305+P351+P338, P321, P332+P313, P337+P313, P362
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
Safety data sheet (SDS) Coleparmer MSDS
Related compounds
Related compounds
 Copper(II) acetate
Chromium(II) acetate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Rhodium(II) acetate is the coordination compound with the formula Rh2(AcO)4, where AcO− is the acetate ion (CH
3CO−
2). This dark green powder is slightly soluble in polar solvents, including water. It is used as a catalyst for cyclopropanation of alkenes. It is a widely studied example of a transition metal carboxylate complex.[2]

Preparation

Rhodium(II) acetate is usually prepared by the heating of hydrated rhodium(III) chloride in a methanol-acetic acid mixture. The crude product is the bis(methanol) complex, but it is easily desolvated.[2][3]

Structure and properties

The structure of rhodium(II) acetate features a pair of rhodium atoms, each with octahedral molecular geometry, defined by four acetate oxygen atoms, water, and a Rh–Rh bond of length 2.39 Å. The water adduct is exchangeable, and a variety of other Lewis bases bind to the axial positions.[4] Copper(II) acetate and chromium(II) acetate adopt similar structures.

Chemical properties

The dimer binds a number of classical Lewis bases to form 2:1 adducts:

Its Lewis acidity is eclipsed by the enhanced reactivity of rhodium(II) trifluoroacetate, which even binds arenes and alkenes.

The acetate group can be replaced by other carboxylates of strong acids. The yields are nearly quantitative.

Like almost all rhodium complexes, rhodium(II) acetate catalyzes many reactions such as hydrogenation and hydrosilylation. No evidence exists for mechanisms and the behavior has not motivated further work. The important observation that rhodium(II) acetate catalyzes reactions of diazo compounds has led to considerable research, but mostly focused on the trifluoroacetate or chiral derivatives.

References

  1. ^ "Dirhodium tetraacetate". pubchem.ncbi.nlm.nih.gov. Retrieved 14 December 2021.
  2. ^ a b Felthouse, Timothy R. (1982). "The Chemistry, Structure, and Metal-Metal Bonding in Compounds of Rhodium(II)". Progress in Inorganic Chemistry. Vol. 29. pp. 73–166. doi:10.1002/9780470166307.ch2. ISBN 978-0-471-09370-1.
  3. ^ Rempel, G. A.; Legzdins, P.; Smith, H.; Wilkinson, G. (1972). "Tetrakis(acetato)dirhodium(II) and Similar Carboxylato Compounds". Inorganic Syntheses. Vol. 13. pp. 90–91. doi:10.1002/9780470132449.ch16. ISBN 9780470132449. {{cite book}}: |journal= ignored (help)
  4. ^ Cotton, F. A.; Deboer, B. G.; Laprade, M. D.; Pipal, J. R.; Ucko, D. A. (1971). "The crystal and molecular structures of dichromium tetraacetate dihydrate and dirhodium tetraacetate dihydrate". Acta Crystallogr B. 27 (8): 1664. doi:10.1107/S0567740871004527.