Carbonylhydrido-tris(triphenylphosphine)rhodium(I), carbonyl-tris(triphenylphosphine)rhodium(I) hydride, forms yellow crystals that are stable in
air, mp 172 – 174℃ in a closed nitrogen-filled
capillary. It is readily soluble in benzene, chloroform, and dichloromethane. In solution, one
phosphine ligand is readily lost by dissociation to
give a 16-electron complex that is an active
catalyst for the hydrogenation of alkenes and for
hydroformylation.
Hydrogenation, hydrosilation, isomerization, carbonylation, hydroformylation, oxidation
Carbonylhydrido-tris(triphenylphosphine)rhodium(I) is used in industry for the hydroformylation of alkenes by the low pressure oxo (LPO) process developed by Union Carbide, Davy Power Gas, and Johnson Matthey. The reaction takes place rapidly at 25℃ giving a product in which the ratio of n- to iso-aldehydes is very favorable (ca. 20 : 1), a much higher ratio than can be obtained with cobalt catalysts.
Carbonyltris(triphenylphosphine)rhodium(I) hydride is obtained by the reaction of a solution of RhCl3.3 H2O in alcoholic alkali with aqueous formaldehyde (the carbon monoxide source) and an excess of triphenyl phosphine. The commercial product is a microcrystalline powder with a purity of 97 % (Degussa).
