A study on the species present in solutions of hypervalent iodine(III) reagents by electrospray ionization mass spectrometry

Solutions of iodobenzene diacetate in CH3CN, AcOH, MeOH/H2O and MeOH (with or without base) were analyzed by electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (ESI-MS/MS). The major species in CH3CN, AcOH and MeOH/H2O solutions are [PhI(OAc)2Na]+, [PhI(OAc)2K]+, [PhI]+, [PhIOAc]+, [PhIOH]+, [PhIO2Ac]+, [PhIO2H]+ and the dimer [Ph2I2O2Ac]+. On the other hand, MeOH solutions showed [PhIOMe]+ as the most abundant species. A similar result was observed adding 2, 3 or 4 equiv of KOH to MeOH solutions. However, in the presence of 10 equiv of KOH, probably occurs the formation of a polymeric material. Similarly, ESI-MS analysis of the MeOH solution of iodobenzene bis(trifluoroacetate) showed a pattern analogous to that observed for the corresponding solutions of PhI(OAc)2. However, ESI-MS spectral data of PhI(O2CCF3)2 of CH3CN suggests that the main species in solutions is iodosylbenzene, which contrasts with the results obtained for PhI(OAc)2.