Dissociation kinetics study of Ce(III) complexes with H8dotp (H8dotp = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis (methylphosphonic acid))

The dissociation kinetics of cerium(III) complexes with H8dotp (I = 3.0 mol dm−3 (Na,H)ClO4, t = 25–60 °C) was studied by means of molecular absorption spectroscopy in the UV region. The mechanism of the proton-assisted reaction was proposed, and the activation parameters (Ea = 111 ± 20 kJ mol−1, ΔH≠ = 108 ± 20 kJ mol−1, ΔS≠ = 32 ± 62 J K−1 mol−1) for the rate-determining step were calculated.