Disproportionation of neptunium(5) in perchloric acid solutions containing chromium(3) ions

The spectrophotometric method was used to study the disproportioning reaction of neptunium(5) ions bound in an inert cation-cation complex with chromium(3) ions in 9.08 M chloric acid at 22 deg C. The stochiometric nature of the reaction was found to correspond to the equation 2(NpOsub(2)sup(+))sub(Cr(3))=Np(4)+Np(6). The effective rate constant, K, is 1.81x10-4 min-1 and approaches in its value the dissociation rate constant of the (NpOsub(2)sup(+))sub(Cr(3)) complex. This seems to indicate that the reaction-controlling stage is represented by the inert complex dissociation reaction