Many-Body Potentials for Aqueous Be²⁺ Derived from ab Initio Calculations

Abstract

An effective three-body potential for the aqueous Be ion has been constructed from a large number of high-level ab initio cluster calculations. The new potential was validated in subsequent molecular dynamics simulations of both gas phase ion-water clusters and bulk liquid. The structures of the first and second solvation shells were studied using radial distribution functions and angular distribution functions. The vibrational spectrum of Be and first shell waters was examined by computing power spectra from the molecular dynamics simulations. The observed bands showed reasonable agreement with experimental spectroscopic frequencies. The potential of mean force for water exchange between the first and second solvation shells was calculated and the energy barrier for exchange was found to have improved agreement with experiment relative to two-body force fields. Examination of the solvation structure near the transition state yielded results consistent with an associative mechanism.

Solvent-induced ion separation of a beryllium scorpionate complex

“…Spontaneous ion separation of the scorpionate beryllium complex TpBeI 1 (Tp = 1-trispyrazolylborate) occurs upon treatment with THF, yielding [TpBe(thf)]I 2, which was characterized by heteronuclear NMR spectroscopy ( 1 H, 9 Be, 13 C) and structurally characterized by single crystal X-ray diffraction. 2 represents a rare example of a structurally characterized monocationic beryllium complex and to the best of our knowledge, the synthesis of 2 by a solvent-induced ion separation has previously only been observed in reactions of beryllium dihalides with strong Lewis bases.…”

“…12 The reason for the solvent-induced ion separation might be that the bonding interaction between beryllium and iodine is rather covalent and highly polarized toward the metal center as is typical for small metal cations ("hard" Lewis acids) such as Li + and Be 2+ . 13,14 In addition, the bond dissociation energy (BDE) in TpBeI is expected to be lower compared to the lighter homologues TpBeX (X = F, Cl, Br), which is also expected due to the classical HSAB (Hard and Soft Acids and Bases) concept, since iodine is softer than the lighter halides. Crystals of 2 suitable for a single crystal X-ray analysis were formed upon storage of a solution of TpBeI in THF at 40 °C for 6h.…”

“…CHCHCH)N)3Be(THF)I) 13. C{ 1 H} NMR (75.5 MHz, 25 °C, THF-d8): δ = 105.0 HB(N(CHCHCH)N)3Be(THF)I), 133.7 HB(N(CHCHCH)N)3Be(THF)I).…”