Table 4. Rate and Equilibrium Constants Characterizing the Dissociation of the CHXOCTAPA^4– Complexes and Related Systems (25 °C).

	[LuCHXOCTAPA]−	[GdCHXOCTAPA]−a	[GdOCTAPA]−b	[GdDTPA]2–c	[GdDO3A]d
k1/M–1 s–1	3.74 ± 0.06 × 10–2	1.60 × 10–2	11.8	0.58	0.023
k2/M–2 s–2			2.5 × 104	9.7 × 104
k3Cu/M–1 s–1	6.3 ± 0.3 × 10–4	6.8 × 10–4	22.5	0.93
k6Cu/M–2 s–1	5.1 ± 0.3 × 105		5.0 × 109
KH		737	2.6	100
KCu	12.1 ± 1.6	48		13
t1/2/he	876	1.49 × 105	0.15	202	2.10 × 105

^aData from ref (38).

^bData from ref (26).

^cData from ref (25).

^dData from ref (48).

^eHalf-lives determined at pH 7.4 and [Cu²⁺] = 1 μM.