Chlorohydridotris(triphenylphosphine)rhodium(III) Chloride

[12124-48-0]  · C54H46Cl2P3Rh  · Chlorohydridotris(triphenylphosphine)rhodium(III) Chloride  · (MW 961.72)

(catalyst for carboxamide decomposition,2 chloroacetate carbonylation,3 hydrogen transfer,4 and hydrogenation5)

Physical Data: a-form mp (dec) 160 °C; b-form mp (dec) 100 °C.

Analysis of Reagent Purity: elemental analysis.

Preparative Method: prepared from Rhodium(III) Chloride and Triphenylphosphine.1

Carboxamide Decomposition.

The distillation of secondary carboxamides over this catalyst results in generation of nitriles (eq 1).2 Higher yields are reported when Chlorotris(triphenylphosphine)rhodium(I) is employed for production of nitriles from carboxamides. Use of various iridium complexes, palladium complexes, and ruthenium complexes results in a less efficient process.

The title reagent also catalyzes the transformation of malonamides into acetamides (eq 2).2 In this case, the activities of RhCl(PPh3)3 and HRhCl2(PPh3)3 do not mirror one another with respect to substrate selectivity and rate. This disparate reactivity is probably a reflection of the different mechanistic pathways followed by these two catalysts: RhCl(PPh3)3 requires oxygen to be catalytically active while HRhCl2(PPh3)3 does not.


The carbonylation of chloroacetates has been effected using HRhCl2(PPh3)3 adsorbed onto active carbon as a catalyst (eq 3).3 When carbon monoxide pressures were less than 20 bars, lower product selectivities were observed. Rhodium(III) Chloride and RhCl(PPh3)3 can also function as catalysts for the carbonylation of chloroacetates.

Alkene Isomerization.

Exposure of 1-pentene to HRhCl2(PPh3)3 results in isomerization of the alkene to an internal position (eq 4).4 Presumably this reaction occurs through the addition-elimination of a rhodium hydride species. Other catalysts that exhibit comparable activity in this type of isomerization are RhCl3(PPh3)3 and HRuCl(PPh3)3.


HRhCl2(PPh3)3 supported on silica can be used as a hydrogenation catalyst (eq 5).5 In a comparison with other rhodium-based catalysts the following reactivity order emerges: RhCl(PPh3)3 > H2RhCl(PPh3)3 > HRhCl2(PPh3)3.

1. Sacco, A.; Ugo, R.; Moles, A. JCS(A) 1966, 1670.
2. Blum, J.; Fisher, A.; Greener, E. T 1973, 29, 1073.
3. Hudson, B.; Taylor, P. C.; Webster, D. E.; Wells, P. B. Discuss. Faraday Soc. 1968, 37.
4. Gobolos, S.; Talas, E.; Margitfalvi, J. Stud. Surf. Sci. Catal. 1988, 41, 337.
5. Kochloefl, K.; Liebelt, W. CC 1977, 510.

Jeffrey A. McKinney

Zeneca Pharmaceuticals, Wilmington, DE, USA

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