Unraveling a Trifecta of Weak non-Covalent Interactions: The Dissociation Energy of the Anisole-Ammonia 1:1 Complex

The anisole-ammonia 1:1 complex is a challenge for both experiment and theory. Early studies supported a non-planar structure, involving a trifecta of weak non-covalent interactions: N-H/O, N-H/π, and C-H/N. The calculated structure and binding energy of the complex proved remarkably sensitive to the level of theory employed. Here, we report the first experimental measurement of the ground state dissociation energy of the complex, and derive an excited (S1) state dissociation energy that is in excellent agreement with the cutoff observed in the experimental excitation spectrum. Results are compared with previous predictions and new calculations based on benchmarked Density Functional Theory methods