Rhodium(II) trifluoroacetate

Rhodium(II) trifluoroacetate
Names
	Other names Dirhodium tetrakis(trifluoroacetate); Dirhodium tetra(trifluoroacetate); Rhodium(II) trifluoroacetate dimer;
Identifiers
CAS Number	31126-95-1;
3D model (JSmol)	Interactive image;
ChemSpider	380904;
ECHA InfoCard	100.159.403
EC Number	631-136-4;
PubChem CID	10985187;
	InChI InChI=1S/4C2HF3O2.2Rh/c43-2(4,5)1(6)7;;/h4(H,6,7);; Key: SZQVMUPTZFMHQT-UHFFFAOYSA-N;
	SMILES C(=O)(C(F)(F)F)O.C(=O)(C(F)(F)F)O.C(=O)(C(F)(F)F)O.C(=O)(C(F)(F)F)O.[Rh].[Rh];
Properties
Chemical formula	C8F12O8Rh2
Molar mass	657.872 g·mol−1
Appearance	green solid
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Rhodium trifluoroacetate is the chemical compound with the formula Rh₂(O₂CCF₃)₄. It is used as a catalyst in the synthesis of some organic compounds.^[1] The compound and its derivatives have been extensively characterized by X-ray crystallography. It adopts the Chinese lantern structure seen for many dimetal carboxylate complexes. This structure accommodates a Rh-Rh bond, the existence of which explains the diamagnetism of this Rh(II) species. The Rh-Rh distance is 238 pm.^[2]

The anhydrous complex is a green volatile solid. It is prepared by dissolving rhodium(II) acetate in hot trifluoroacetic acid:^[3]

Rh₂(O₂CCH₃)₄ + 4 HO₂CCF₃ → Rh₂(O₂CCF₃)₄ + 4 HO₂CCH₃

This reaction expels acetic acid. The Rh-Rh bond is retained.

Reactions

Rhodium(II) trifluoroacetate forms adducts with a variety of Lewis bases. The structures typically have a 2:1 stoichiometry, with one base binding at the "axial" position on each of the two Rh(II) centers:

Rh₂(O₂CCF₃)₄ + 2 L → Rh₂(O₂CCF₃)₄L₂ (L = CO, RCN, R₂SO, R₃P, ...)

Rhodium(II) trifluoroacetate binds even very weak bases, moreso than does rhodium(II) acetate. It even forms adducts with hexamethylbenzene and with S₈.^[4]

Rhodium(II) trifluoroacetate catalyzes cyclopropanation of alkenes by diazo compounds:^[1] RCH=CR'H + CH₃CH₂O₂CCH(N₂) → cyclo−(RCH)(R'CH)(CH₃CH₂O₂CCH) + N₂

References

^ ^a ^b Doyle, Michael P.; Davies, Huw M. L.; Manning, James R.; Yu, Yang (2018). "Dirhodium(II) tetrakis(trifluoroacetate)". EEROS. doi:10.1002/047084289X.rd461.pub2. ISBN 978-0-471-93623-7.
^ Cotton, F. Albert; Dikarev, Evgeny V.; Feng, Xuejun (1995). "Unligated Dirhodium Tetra(trifluoroacetate): Preparation, Crystal Structure and Electronic Structure". Inorganica Chimica Acta. 237 (1–2): 19–26. doi:10.1016/0020-1693(95)04662-S.
^ 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.
^ Cotton, F. Albert; Dikarev, Evgeny V.; Petrukhina, Marina A. (2001). "Neutral Cyclooctasulfur as a Polydentate Ligand: Supramolecular Structures of [Rh₂(O₂CCF₃)₄]_n(S₈)_m (n:m=1:1, 3:2)". Angewandte Chemie International Edition. 40 (8): 1521–1523. doi:10.1002/1521-3773(20010417)40:8<1521::AID-ANIE1521>3.0.CO;2-M.

[Huw-1] Doyle, Michael P.; Davies, Huw M. L.; Manning, James R.; Yu, Yang (2018). "Dirhodium(II) tetrakis(trifluoroacetate)". EEROS. doi:10.1002/047084289X.rd461.pub2. ISBN 978-0-471-93623-7.

[2] Cotton, F. Albert; Dikarev, Evgeny V.; Feng, Xuejun (1995). "Unligated Dirhodium Tetra(trifluoroacetate): Preparation, Crystal Structure and Electronic Structure". Inorganica Chimica Acta. 237 (1–2): 19–26. doi:10.1016/0020-1693(95)04662-S.

[3] 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.

[4] Cotton, F. Albert; Dikarev, Evgeny V.; Petrukhina, Marina A. (2001). "Neutral Cyclooctasulfur as a Polydentate Ligand: Supramolecular Structures of [Rh₂(O₂CCF₃)₄]_n(S₈)_m (n:m=1:1, 3:2)". Angewandte Chemie International Edition. 40 (8): 1521–1523. doi:10.1002/1521-3773(20010417)40:8<1521::AID-ANIE1521>3.0.CO;2-M.

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