Table 2. Comparison of Calculated and Experimental Thermodynamic and Geometric Parameters for the Metal Models Presented in This Work^a.

		calculatedc			experimentald
ions		ΔGhydr	metal–O	CN	ΔGhydr	metal–O	CN
Mg2+b	minC4	–454.2 ± 0.5	2.09 ± 0.01	6.0	–454.2	2.09	6.0
	midC4	–453.6 ± 0.3	2.09 ± 0.01	6.0
	maxC4	–454.6 ± 0.5	2.09 ± 0.01	6.0
Al3+		–1101.2 ± 0.8	1.89 ± 0.003	6.0	–1100.3	1.89	6.0
Fe3+		–1032.5 ± 0.4	2.03 ± 0.003	6.0	–1033.0	2.03	6.0
Cr3+		–1037.0 ± 0.3	1.98 ± 0.006	6.0	–1037.0	1.96	6.0

^aΔG_hydr, metal–O, and CN denote the hydration free energies (kcal mol^–1), metal–oxygen distances in aqueous solution (Å) and coordination numbers of each metal ion, respectively.

^bFor a definition of the parameter sets that describe the three Mg²⁺ models, see Table 1, and for the radial distribution functions see Figure S7.

^cThe calculated hydration free energies are a sum of ΔG_LJ126, ΔG_C4 and ΔG_elec, respectively, as listed in Table S1 for all the models.

^dAll the experimental hydration free energy values were obtained from Noyes,³⁶ as described in the main text, while the experimental metal–oxygen distances and the coordination numbers were taken from Marcus’ review.³⁷