Kinetic studies of the [NpO(2)(CO(3))(3)](4-) ion at alkaline conditions using (13)C NMR.

摘要: Carbonate ligand-exchange rates on the [NpO2(CO3)3]4– ion were determined using a saturation-transfer 13C nuclear magnetic resonance (NMR) pulse sequence in pH range of 8.1 ≤ 10.5. Over 9.3 10.5, which compares most directly with previous work Stout et al.,1 we find an average rate, activation energy, enthalpy, and entropy kex298 = 40.6(±4.3) s–1, Ea =45.1(±3.8) kJ mol–1, ΔH‡ 42.6(±3.8) ΔS‡ −72(±13) J mol–1 K–1, respectively. These parameters are similar to al. results at 9.4. However, their room-temperature rate 9.4, 143(±1.0) is ∼3 times faster than what experimentally 9.3: 45.4(±5.3) s–1. Our for also by factor relative isoelectronic [UO2(CO3)3]4– as reported Brucher al.2 13(±3) Consistent ion, evidence proton-enhanced pathway carbonate exchange [...