Diaryliodoniums as Hybrid Hydrogen- and Halogen-Bond-Donating Organocatalysts for the Groebke–Blackburn–Bienaymé Reaction

H nuclear magnetic resonance (NMR) titrations, in conjunction with those from DFT calculations, indicate that this could be explained in terms of the additional energy required for the rotation of the phenyl ring in the diphenyliodonium cation during ligation of the substrate.