Title: Wilkinson's Catalyst
CAS Registry Number: 14694-95-2
CAS Name: (SP-4-2)-Chlorotris(triphenylphosphine)rhodium
Molecular Formula: C54H45ClP3Rh
Molecular Weight: 925.21
Percent Composition: C 70.10%, H 4.90%, Cl 3.83%, P 10.04%, Rh 11.12%
Literature References: Dimorphic compd exists in two forms, red and orange, both possess the same chemical properties. Prepn: J. F. Young et al., Chem. Commun. 1965, 131; J. A. Osborn, G. Wilkinson, Inorg. Synth. 10, 67 (1967); eidem, ibid. 28, 77 (1990). Crystal structure: M. J. Bennett, P. B. Donaldson, Inorg. Chem. 16, 655 (1977). Structure and properties: Y. Nishihara et al., Organometallics 21, 825 (2002). Mechanistic study: S. B. Duckett et al., J. Am. Chem. Soc. 116, 10548 (1994). Reduction of nitrobenzenes: H. R. Brinkman et al., Synth. Commun. 26, 973 (1996); selective hydrogenation of olefins: A. Jourdant et al., J. Org. Chem. 67, 3163 (2002). Comprehensive review of properties and reactions: F. H. Jardine, Prog. Inorg. Chem. 28, 63-202 (1981); of hydrogenations: F. Joo, Acc. Chem. Res. 35, 738-745 (2002).
Properties: Dark, burgundy-red crystals from hot ethanol. Orange crystals from < 200 ml ethanol soln refluxed for five minutes; converted to red form on further refluxing. mp 157°. Soly in chloroform, dichloromethane (25°): ~20 g/l; in benzene, toluene (25°): ~2 g/l; much less sol in acetic acid, acetone and other ketones, methanol, lower aliphatic alcohols. Virtually insol in alkanes and cyclohexane. Donor solvents such as pyridine, dimethyl sulfoxide, acetonitrile dissolve the complex with reaction. Solns are air sensitive. Orange form d 1.363; red form d 1.379.
Melting point: mp 157°
Density: d 1.363; d 1.379
Use: Homogeneous hydrogenation catalyst. |