Chillemi Giovanni, Mancini Giordano, Sanna Nico, Barone Vincenzo, Della Longa Stefano, Benfatto Maurizio, Pavel Nicolae V, D'Angelo Paola
CASPUR, Consortium for Supercomputing. Applications,Via dei Tizii 6b, 00185 Rome, Italy.
J Am Chem Soc. 2007 May 2;129(17):5430-6. doi: 10.1021/ja066943z. Epub 2007 Apr 6.
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.
通过结合X射线吸收光谱（XAS）和量子力学/分子动力学（QM/MD）计算的广泛研究，揭示了水溶液中汞（II）水合络合物出人意料的七重配位情况。事实上，汞（II）离子普遍接受的八面体溶剂化与XAS结果不一致。接下来，精确的QM计算指出了具有C2对称性的七配位结构的显著稳定性，并且通过包含多体效应的新相互作用势进行的长时间MD模拟表明，水合络合物具有相当灵活的结构，在大多数时间对应于七配位物种。这一情况与X射线吸收近边结构实验数据完全一致，该数据明确显示出对七重而非六重配位的偏好。
