title: Structural, dynamical, and transport properties of the hydrated halides: How do At(-) bulk properties compare with those of the other halides, from F(-) to I(-)?
abstract: The properties of halides from the lightest, fluoride (F(-)), to the heaviest, astatide (At(-)), have been studied in water using a polarizable force-field approach based on molecular dynamics (MD) simulations at the 10 ns scale. The selected force-field explicitly treats the cooperativity within the halide-water hydrogen bond networks. The force-field parameters have been adjusted to ab initio data on anion/water clusters computed at the relativistic Möller-Plesset second-order perturbation theory level of theory. The anion static polarizabilities of the two heaviest halides, I(-) and At(-), were computed in the gas phase using large and diffuse atomic basis sets, and taking into account both electron correlation and spin-orbit coupling within a four-component framework. Our MD simulation results show the solvation properties of I(-) and At(-) in aqueous phase to be very close. For instance, their first hydration shells are structured and encompass 9.2 and 9.1 water molecules at about 3.70 ± 0.05 Å, respectively. These values have to be compared to the F(-), Cl(-), and Br(-) ones, i.e., 6.3, 8.4, and 9.0 water molecules at 2.74, 3.38, and 3.55 Å, respectively. Moreover our computations predict the solvation free energy of At(-) in liquid water at ambient conditions to be 68 kcal mol(-1), a value also close the I(-) one, about 70 kcal mol(-1). In all, our simulation results for I(-) are in excellent agreement with the latest neutron- and X-ray diffraction studies. Those for the At(-) ion are predictive, as no theoretical or experimental data are available to date.
authors.affiliation: Université de Lille, CNRS, UMR 8523-PhLAM-Physique des Lasers Atomes et Molécules, F-59000 Lille, France.
authors.forename: Florent
authors.initials: F
authors.lastname: Réal
authors.affiliation: Université de Lille, CNRS, UMR 8523-PhLAM-Physique des Lasers Atomes et Molécules, F-59000 Lille, France.
authors.forename: André Severo Pereira
authors.initials: AS
authors.lastname: Gomes
authors.affiliation: Université de Lille, CNRS, UMR 8523-PhLAM-Physique des Lasers Atomes et Molécules, F-59000 Lille, France.
authors.forename: Yansel Omar
authors.initials: YO
authors.lastname: Guerrero Martínez
authors.affiliation: CEISAM UMR CNRS 6230, Université de Nantes, 2 Rue de la Houssinière, BP 92208 F-44322 Nantes Cedex 3, France.
authors.forename: Tahra
authors.initials: T
authors.lastname: Ayed
authors.affiliation: CEISAM UMR CNRS 6230, Université de Nantes, 2 Rue de la Houssinière, BP 92208 F-44322 Nantes Cedex 3, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Galland
authors.affiliation: Laboratoire de Biologie Structurale et Radiobiologie, Service de Bioénergétique, Biologie Structurale et Mécanismes, Institut de Biologie et de Technologies de Saclay, CEA Saclay, F-91191 Gif sur Yvette Cedex, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Masella
authors.affiliation: Université de Lille, CNRS, UMR 8523-PhLAM-Physique des Lasers Atomes et Molécules, F-59000 Lille, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Vallet