Structure and dynamics of the hydrated magnesium ion and of the solvated magnesium carbonates: insights from first principles simulations
Structure and dynamics of the hydrated magnesium ion and of the solvated magnesium carbonates: insights from first principles simulations
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DOI：
10.1039/b915329b
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发表时间：
2010-01-01
影响因子：
3.3
通讯作者：
de Leeuw, Nora H.
中科院分区：
文献类型：
--
作者：
Di Tommaso, Devis;de Leeuw, Nora H.
我们报告的第一性原理分子动力学模拟的基础上的密度泛函理论和Car-Parrinello方法研究的结构和动力学的水合Mg 2+离子和溶剂化MgHCO 3+和MgCO 3复合物在水溶液中。根据这些模拟，水合镁离子的第一水合壳层由六个水分子组成，而在溶剂化的碳酸氢镁和碳酸镁络合物中，Mg 2+主要是五配位的，这表明当与镁配位时，HCO 3-和CO 32-阴离子减少了其配位范围。我们的模拟结果表明，碳酸氢镁和碳酸镁在溶液中最稳定的单体结构是Mg[eta（1）-HCO 3]（H2O）（4）（+）和Mg[eta（1）-CO 3]（H2O）（4），即优选的水合数为4，而碳酸氢镁以单齿模式与镁配位。通过对Mg ~（2+）第一、二水合层中水分子交换过程的分析表明，HCO ~（3-）或CO ~（32-）配体通过使镁的水合层更“不稳定”而影响镁配位球的动力学.此外，分子动力学模拟的非相关的Mg 2 +/Cl-对在水中的建议，尽管可以忽略不计的差异，在Mg 2+的配位球，氯阴离子有显着的影响，在第二水合壳层的Mg 2+的水交换速率。
We report first principles molecular dynamics simulations based on the density functional theory and the Car-Parrinello method to study the structures and dynamics of the hydrated Mg2+ ion and of the solvated MgHCO3+ and MgCO3 complexes in aqueous solution. According to these simulations, the first hydration shell of the hydrated magnesium ion consists of six water molecules, whereas in the solvated magnesium bicarbonate and magnesium carbonate complexes the Mg2+ is mostly five-coordinated, which indicates that when coordinated to magnesium the HCO3- and CO32- anions reduce its the coordination sphere. Our simulations show that the structures of the most stable monomers of magnesium bi-carbonate and magnesium carbonate in solution are Mg[eta(1)-HCO3](H2O)(4)(+) and Mg[eta(1)-CO3](H2O)(4), i.e. the preferred hydration number is four, while the (bi-) carbonate is coordinated to the magnesium in a monodentate mode. The analysis of the exchange processes of the water molecules in the first and second hydration shell of Mg2+ shows that the HCO3- or CO32- ligands affect the dynamics of the magnesium coordination spheres by making its hydration shell more "labile''. Furthermore, molecular dynamics simulations of the non-associated Mg2+/Cl- pair in water suggest that, despite negligible differences in the coordination spheres of Mg2+, the chloride anion has a significant influence on the water exchange rates in the second hydration shell of Mg2+.