Speciation of Diaryliodonium Salts in Solution and Their Reactivity Towards \u3ci\u3eN\u3c/i\u3e-nucleophiles (Phthalimide and Amines) and \u3ci\u3eO\u3c/i\u3e-nucleophiles (Phenols and Phenoxide)

Benzenoid rings are prevalent in pharmaceutical drug molecules, agrochemical molecules and even in some polymers used in electronic device. Aryl rings are often installed using metal catalysis, however, metal free arylations are known but limited. Diaryliodonium salts are novel electrophilic arylating agents. Herein, metal free N-arylation of phthalimide and diarylether formation using aryl(TMP)iodonium salts is described. The structure of diaryliodonium salts has been primarily studied in either the solid state or in-silico. The structure and speciation of diaryliodonium salts in solution is not well explored. In this work evidence of dimer formation of aryl(Mes)iodonium salts in chloroform using mass spectrometry (ESI-MS) is described. However, the same dimers were not detected in more polar solvents such as MeCN and MeOH. Conductivity experiments were performed to measure the extent of ionization of iodonium salts. Association constant (KIX) of ion pairing for 64 different combinations of iodonium cations, counter anions and solvents were obtained. ESI-MS and conductivity experiments in chloroform suggested dimerization of aryl(Mes)iodonium salts. Dimerization constants (K(IX)2) of aryl(Mes)iodonium salts were measured using 1H NMR experiments. Twenty different K(IX)2 values were reported including various auxiliary and counter anion of diaryliodonium salts. Furthermore, Lewis acid-base interactions were measured between aryl(TMP)iodonium salts and aliphatic amines (both cyclic and acyclic) using 1H NMR titration. Binding constant (KIN) for over 25 different combinations of iodonium salts and amines were reported. Lewis basicity scale was then developed using various methods. Finally, a kinetic study of N-arylation of DABCO and formation of diaryl ether (using diphenyliodonium salt) was performed. Difference in observed order of these reactions, suggest that although these reactions might look similar, the product formation occurs through different mechanisms