Speaker: Jean Christophe Tremblay, Université de Lorraine

Matrix isolation spectroscopy has emerged as a powerful experimental tool to investigate polyfluoride anions and shed light on their peculiar bonding properties. The technique involves confining metastable species within a defective noble-gas crystal at low temperatures and characterizing their vibrational properties by IR spectroscopy. A central theoretical challenge is to explain why weakly bound polyfluoride anions show unexpected sensitivity to supposedly inert cryogenic matrices [1,2].

In this contribution, we present a theoretical framework for accurately investigating weakly interacting guest-host systems, enabling the subtle frequency shifts observed in different matrices to be rationalized in simple chemical terms [3-5]. Furthermore, it will be shown that confinement in a neon matrix leads to heavy-atom tunnelling in F₅^- [6], helping resolve a structure that had remained elusive for over a decade [2,7].

References:

1. L. Andrews and X. Wang, Phys. Chem. Chem. Phys., 2018, 20, 23378
2. S. Riedel, T. Köchner, X. Wang and L. Andrews, Inorg. Chem., 2010, 49, 7156
3. F. Bader, JC Tremblay, B. Paulus PCCP, 2021, 23, 886
4. F. Bader, JC Tremblay, B. Paulus PCCP, 2022, 24, 3555
5. F. Bader et al. J. Phys.Chem. A, 2021, 125, 6221
6. C. Müller et al. Nat. Commun. 2025, 16, 1-16.
7. T. Vent-Schmidt et al. Angew. Chem. Int. Ed. 2015, 54, 8279