Investigation of the Jahn–Teller effect in the ${\rm C}_{60}^{{-} } $ monoanion under high pressure

We report the Jahn–Teller (JT) dynamics of the ${\rm C}_{60}^{{-} } $ monoanion under pressure in (Ph 4 P) 2 IC 60 . (Ph 4 P) 2 IC 60 was synthesized by electrochemical crystallization and investigated by infrared transmission measurements up to 5 GPa. The behavior of two T 1 u vibrational modes of ${\rm C}_{60}^{{-} } $ , which exhibit signatures of the dynamic JT effect at ambient conditions, was followed under pressure. The pressure‐induced transition from the dynamic to the static JT state was observed at ∼2 GPa. Due to symmetry lowering related to the dynamic JT effect, the G 1 u mode is activated and shows a splitting at the pressure‐induced dynamic‐to‐static JT distortion.