Table 3.

Proton assisted dissociation rates for Ce³⁺ complexes of DOTA and selected DOTA-tetraamides.

Ligand	k0 (s−1)	k1 (M−1s−1)
DTMAa	1.1 × 10−5	2.6 × 10−5
L4	(7.8 ± 0.4) × 10−5	(1.26 ± 0.02) × 10−4
L8	(9.6 ± 0.4) × 10−5	(1.08 ± 0.02) × 10−4
L12	—b	(3.1 ± 0.1) × 10−3
DOTAc	n.d.	8 × 10−4

^a)from reference [5];

^b)the large negative value may be explained by a different mechanism accessible for dissociation at lower acid concentrations;

^c)from reference [19].