. 2024 Mar 12;15(15):5694–5710. doi: 10.1039/d3sc04493a

The six [Co(Xdiox)(Me_ntpa)]⁺ model complexes, the experimentally observed valence tautomer, respective solvent, transition temperature (T_1/2), and the experimental enthalpy changes (ΔH) for each complex, the individually quantified corrections for solvent (ΔE_S), relativistic (ΔE_R) and thermal effects (ΔE_T) calculated with BP86-D3(BJ)/def2-TZVP and the resulting quasi-experimental energies (ΔQ_E).

Model complex	Reported valence tautomer	Experimental		Ref.	Calcd. correction/kJ mol⁻¹			ΔQ_E/kJ mol⁻¹
Model complex	Reported valence tautomer	Solvent (T_1/2/K)	ΔH^a/kJ mol⁻¹	Ref.	ΔE_S	ΔE_R	ΔE_T	ΔQ_E/kJ mol⁻¹
1	LS-Co^III-cat	MeCN	61	85	32.7	11.8	−3.7	20.2
2	LS-Co^III-cat	MeCN	34	85	32.8	11.1	−5.4	−4.5
3	VT	MeCN^b	6	85	29.5	10.8	−3.5	−30.8
4	HS-Co^II-sq	MeCN	−25	85	29.9	9.8	−3.0	−61.7
5	VT	DCM/250	31	86	32.3	10.2	−5.7	−5.8
6	VT	DCM (291)	35	33	32.7	9.4	−5.3	−5.7^c
		DCE (295)	32	33	33.3	9.4	−5.2
		MeCN (359)	32	33	37.1	9.4	−4.6

Experimental ΔH for complexes 1–4 in ref. 85 were derived from Gibbs free energy changes acquired through voltametric measurements in MeCN at 298 K, with an added component of entropy changes estimated from Fe-analogues. For complex 5, ΔH was determined using electronic absorption spectroscopy in DCM and for complex 6, Evans NMR method was employed in DCM, DCE and MeCN.

T _1/2 not reported.

Average of ΔQ_E of three experimental conditions are used for complex 6.