Table 3.

Relaxation parameters calculated from the simultaneous fitting of the temperature dependence of the water ¹⁷O transverse relaxation rate and the NMRD profiles of Gd(3) and Gd(6).

	Gd(3)	Gd(6)	Gd(8)[a]
r1p298 [mm−1s−1]	6.38 ± 0.04	5.05 ± 0.02	5.0
q	1	1	1
Δ2 [s−2 × 1019]	1.9 ± 0.1[b]	1.0 ± 0.1[b]	1.4
τv298 [ps]	58 ± 7[b]	34 ± 4[b]	40
τR298 [ps]	141 ± 3[b]	86 ± 2[b]	70
τM298 [ps]	0.71 ± 0.09[c]	0.66 ± 0.05[c]	1.3
ΔHM [kJ×mol−1]	28 ± 4[c]	40 ± 3[c]	19
ΔHV [kJ×mol−1]	25 ± 10[c]	28 ± 10[c]	40

^[a]Ref.^[41].

^[b]Best-fit parameters obtained from the analysis of the NMRD profile using the standard value for the average distance between the metal and protons of the inner-sphere water molecule (a = 3.8 Å), and 2.24×10⁻⁵ cm² s⁻¹ for the self-diffusion coefficient of water (D).^[43,50]

^[c]Best-fit parameters obtained from the analysis of the temperature dependence of ¹⁷O NMR transverse relaxation rate in 21 and 19 mm solutions of Gd(3) and Gd(6), respectively, assuming a Gd³⁺ – ¹⁷O scalar coupling constant of −3.8×10⁶ rad s⁻¹ and a Gd^III – ¹⁷O distance of 2.5 Å.^[44,51]