Table 3.

Calculated relative binding energies of the ligands with the post-transition state minimum (kcal/mol, using eq. 6)

Ligand	ΔH	ΔG
urea	−5.6	−3.8
thiourea	−5.3	−4.7
guanidine	−5.4	−3.7
cyanoguanidine	−5.8	−4.3