Charge transfer calculated in the studied ion–CO₂ and DIL–CO₂ complexes using CHELPG and NBO methods. Δϕ = 180 − ϕ angle deviation (ϕ is O–C–O angle in CO₂ molecule).

System		Charge transfer		Δϕ/deg
		CHELPG	NBO
Ion–CO 2 complexes
[Bis(mim)C5]2+–CO2		0.048	0.011	0.26
[N111-C5-mim]2+–CO2	Imidazolium head	0.050	0.012	0.18
	Ammonium head	0.053	0.014	0.04
[Bis(mim)C5-(C4)2]2+–CO2		0.030	0.011	0.19
[NTf2]−–CO2		−0.063	−0.018	4.77
DIL–CO 2 complexes
[Bis(mim)C5][NTf2]2–CO2		−0.033	−0.0039	2.88
[N111-C5-mim][NTf2]2–CO2	Imidazolium head	−0.019	−0.0023	2.3
	Ammonium head	−0.023	−0.0037	2.69
[Bis(mim)C5-(C4)2][NTf2]2–CO2		−0.038	−0.0039	3.13