Fig. 1: Thermodynamic cycle of a dimerization model reaction, driven by strong binding of the product in a host ligand.

The overall reaction is spontaneous, if the sum of the (positive) free energy of dimerization ΔG1 is more than outmatched by the (negative) free energy of binding ΔG4. The dimerization reaction may either take place inside the ligand or the ligand traps small amounts of the product formed in equilibrium outside the ligand. The free energy change from the initial to the final stage is independent of the mechanism (Hess Law)