The acid dissociation constant of the tris(ethylenediamine)cobalt(III) ion

Evidence is given for an acid-base dissociation reaction of tris (ethylenediamine) cobalt (III) ion in basic aqueous solutions. The evidence is based on the nmr chemical shifts of the methylene protons and on the u.v. absorption spectra of Co(en)₃³⁺ ion in basic solution. The equilibrium constant of the deprotonation reaction is estimated by each of the two methods.