title: Evidence for sevenfold coordination in the first solvation shell of Hg(II) aqua ion.
abstract: A quite unexpected sevenfold coordination of the hydrated Hg(II) complex in aqueous solution is revealed by an extensive study combining X-ray absorption spectroscopy (XAS) and quantum mechanics/molecular dynamics (QM/MD) calculations. As a matter of fact, the generally accepted octahedral solvation of Hg(II) ion cannot be reconciled with XAS results. Next, refined QM computations point out the remarkable stability of a heptacoordinated structure with C2 symmetry, and long-time MD simulations by new interaction potentials including many-body effects reveal that the hydrated complex has a quite flexible structure, corresponding for most of the time to heptacoordinated species. This picture is fully consistent with X-ray absorption near-edge structure experimental data which unambiguously show the preference for a sevenfold instead of a sixfold coordination.
authors.affiliation: CASPUR, Consortium for Supercomputing. Applications,Via dei Tizii 6b, 00185 Rome, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Chillemi
authors.forename: Giordano
authors.initials: G
authors.lastname: Mancini
authors.forename: Nico
authors.initials: N
authors.lastname: Sanna
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Barone
authors.forename: Stefano
authors.initials: S
authors.lastname: Della Longa
authors.forename: Maurizio
authors.initials: M
authors.lastname: Benfatto
authors.forename: Nicolae V
authors.initials: NV
authors.lastname: Pavel
authors.forename: Paola
authors.initials: P
authors.lastname: D'Angelo
mesh_terms: D015502:Absorptiometry, Photon; D000465:Algorithms; D008628:Mercury / Q000737:chemistry*; D011789:Quantum Theory; D012996:Solutions; D014867:Water / Q000737:chemistry
chemical_list: D012996:Solutions; D014867:Water; D008628:Mercury