One can subject the reaction sequence in Scheme 1 to a reasonableness check based on bond dissociation energies (BDEs). A more quantitative assessment is available through higher level quantum mechanics. The authors themselves have not commented 2 on this aspect in their current article, which is based on purely experimental aspects. Addressing firstly the thermodynamics of the core equilibrium; -C≡C-I + -Ph ⇄ C⩸C + I-Ph Estimates of the experimentally derived BDE of the C-I bond in C≡C-I + -Ar iodonium salts are in the region of 70-80 kcal/mol. When the iodonium C-I bond cleaves, it is directly replaced by a fourth bond as represented by C⩸C, the BDE of which is experimentally estimated at the much lower value of ~17 kcal/mol. When allowance is made for a gain of ~10 kcal/mol of free energy resulting from increase in entropy, this implies that around 43-53 kcal/mol of bond energy must be recovered by the formation and trapping at ambient temperatures of C2 itself.