For a given ligand choice of the metal center, the ∆EH-L strongly depend on the strengths of the interaction between the metal and the molecule and to the amount of gas adsorbed. Two adsorbed molecules, as in bpac, are more effective that one in exerting the ligand field. Both for the pz and bpac Hofmann-clathrates with Mn and Fe open metal sites, the CO2-metal interaction is too weak to stabilize LS so that negative ∆EH-L are negative therefore precluding the implementation of the proposed spin-crossover mechanism for this gas. This applies to the materials studied here and more generally to frameworks where the open metal is coordinated to a molecule whose ligand field is weak (weaker than the ligands'). On the contrary, the strong CO binding results in a large stabilization of LS state and yields values of ∆EH-L that are positive but too high, with consistently higher values predicted when two gas molecules are adsorbed (bpac) rather than one (pz). An intermediate ligand field is exerted by one N2 molecule adsorbed on Fe(pz)Fe(CN)4 which results in a promising value of ∆EH-L=0.325 eV and a huge change in binding energy (from 1.439 eV to 0.140 eV). Similarly good values are observed for H2 in Fe(bpac)Fe(CN)4 with a ∆EH-L of 0.654 eV and a change in binding energy from 1.007 eV to 0.097 eV, and for H2 in and Fe(bpac)Mn(CN)4, with ∆EH-L of 0.267 eV and a change in binding energy from 1.047 eV and 0.087 eV.