Table 1.

Relative energies with respect to free CO₂ and free cobalt(III)–salen complex of the precursor, transition and product state of the CO₂ insertion reaction as shown in Figure 4.

Salen ligand	trans-Ligand	Precursor statea (preS)	Transition statea (TS)	Product statea (PS)	Activation barrier	Reaction energy
		[kJ·mol−1]	[kJ·mol−1]	[kJ·mol−1]	[kJ·mol−1]	[kJ·mol−1]
1	chloride	−14	31	−47	45	−33
1	CH3C(O)O−	−14	45	−30	59	−16
1ab	CH3C(O)O−	−12	41	−31	53	−19
1bc	CH3C(O)O−	−11	39	−37	50	−26
1	p-methoxyphenolate	−14	41	−33	55	−19
1	CCl3C(O)O−	−21	34	−30	55	−9
1	2,4-dinitrophenolate	−22	68	−29	90	−7
1	2,4,6-trinitrophenolate	−11	79	−16	90	−5
1	TBDd	−14	65	−29	79	−15
1	none	−13	58	−6	71	7
1	ethylene oxide	−17	100	−8	117	9

^aPotential energies relative to free CO₂ and the free cobalt(III)–salen complex, i.e., the reactant state was set to zero for each trans-ligand L.

^bSalen with cyclohexyl backbone, = -C₄H₈-, R^3–6 = H

^cSalen with cyclohexyl backbone, = -C₄H₈-, R^3–6 = t-Bu

^dTBD = 1,5,7-triazabicyclo[4.4.0]dec-5-ene.