Comment on “Understanding the infrared spectrum of the protic ionic liquid [DEMA][TfO] by atomistic simulations” by F. Parisi, Y. Chen, K. Wippermann, C. Korte, P. M. Kowalski, M. Eikerling and C. Rodenbücher, Phys. Chem. Chem. Phys., 2024, 26, 28037

Abstract

A recent article in this journal (F. Parisi et al., Phys. Chem. Chem. Phys., 2024, 26, 28037–28045) misassigned the infrared spectrum of liquid diethylmethylammonium triflate (DEMA TfO), a room-temperature ionic liquid. Results from a fresh simulation similar to theirs are shown here, to explain the error and probe the related question of the degree of hydrogen bonding (there does appear to be some). The two peaks in the NH stretch region are due to intensity borrowing (Fermi resonance) from the one NH stretch fundamental by overtone or combination state(s) involving the NH bend.