Table 2. Benchmarking of Ion–Ligand Interaction Energies^a.

ligand	ΔELa–Lint	ΔΔELa→Caint	diff B98	diff HSE06	diff M06-2x	diff M06
water	–99.2	34.2	+1.6	+1.9	+1.5	+2.4
acetate	–527.8	194.5	–2.4	–0.8	–1.7	–1.4
acetamide	–206.0	95.6	–2.5	–1.4	–2.1	–1.8
N-Me-methanimine	–146.4	68.3	+0.7	+1.5	+1.6	+2.0
MAE			–0.65	+0.30	–0.17	+0.30
MUE			1.80	1.40	1.72	1.90

^aΔE_La–L^int were calculated with CCSD(T)/CBS. ΔΔE_La→Ca values (see text) were used as references for DFT calculations. DFT calculations were performed with the def2-TZVP and different functionals. Geometry optimizations were performed using M06/def2-TZVP. All values are in kcal mol^–1. Values represented as diff are the differences with respect to ΔΔE_La→Ca^int calculated with CCSD(T)/CBS. MAE—mean absolute error. MUE—mean unsigned error.