Towards a Stronger Halogen Bond Involving Astatine: Unexpected Adduct with Bu3PO Stabilized by Hydrogen Bonding

Lu Liu (1) , Ning Guo (1) , Julie Champion (1) , Jérôme Graton (2) , Gilles F Montavon (1) , Nicolas Galland (2) , Rémi Maurice (1)

1 SUBATECH - Laboratoire de physique subatomique et des technologies associées
2 CEISAM - Chimie Et Interdisciplinarité : Synthèse, Analyse, Modélisation

The halogen bond is a powerful tool for the molecular design and pushing the limits of its strength is of major interest. Bearing the most potent halogen-bond donor atom, astatine monoiodide (AtI) was recently successfully probed [Nat. Chem. 2018, 10, 428–434]. In this work, we continue the exploration of adducts between AtI and Lewis bases with the tributylphosphine oxide (Bu3PO) ligand, revealing the unexpected experimental occurrence of two distinct chemical species with 1:1 and 2:1 stoichiometries. The 1:1 Bu3PO⋅⋅⋅AtI complex is found to exhibit the strongest astatine-mediated halogen bond so far (with a formation constant of 10(4.24±0.35)). Quantum chemical calculations unveil the intriguing nature of the 2:1 2Bu3PO⋅⋅⋅AtI adduct, involving a halogen bond between AtI and one Bu3PO molecular unit plus CH⋅⋅⋅O hydrogen bonds chelating the second Bu3PO unit.

Domaines: Radiochimie

Lu Liu, Ning Guo, Julie Champion, Jérôme Graton, Gilles F Montavon, et al.. Towards a Stronger Halogen Bond Involving Astatine: Unexpected Adduct with Bu3PO Stabilized by Hydrogen Bonding. Chemistry - A European Journal, 2020, 26 (17), pp.3713-3717. ⟨10.1002/chem.201905389⟩. ⟨hal-03095955⟩