The formation of pentacyanohydridorhodate(III): kinetic and spectral evidence for the oxidative addition of hydrogen cyanide to the intermediate tetracyanorhodate(I)

Abstract

In the reaction of NaCN with [Rh(CO)₂Cl]₂ evidence has been found for the formation of a transient intermediate which is probably Rh(CN)₄^3–; the u.v.–visible spectrum of the intermediate is reported. The decay of the intermediate, studied by the stopped-flow method, has been identified as the oxidative addition of HCN to Rh(CN)₄^3– to form Rh(CN)₅H^3–; the pH dependence and isotope effect of D₂O on the rate constant have been examined. The oxidative addition of alkyl halides to Rh(CN)₄^3–, Rh(CN)₃CO^2–, and Rh(CN)₂(CO)₂^– is reported and the mechanism of formation of acyl rhodium(III) compounds Rh(CN)₅(COCH₃)^3– is discussed.