Dataset Information

Dynamic ionic radius of alkali metal ions in aqueous solution: a pulsed-field gradient NMR study.

ABSTRACT: The dynamic behavior of alkali metal ions, Li⁺, Na⁺, K⁺, Rb⁺ and Cs⁺ in aqueous solutions is one of the most important topics in solution chemistry. Since these alkali metals contain nuclear magnetic resonance (NMR) active nuclei, it is possible to directly measure the diffusion constants of the alkali metal ions using the pulsed field gradient (PFG) NMR method. In this paper, the ⁷Li, ²³Na, ⁸⁷Rb, ¹³³Cs and ¹H resonances are observed for diffusion constants in aqueous solution and the solvent H₂O. Until now, the values of the diffusion constant have been lacking when discussing hydration effects around alkali metal ions. It is known that the static ionic radius (R _ion) increases with increasing the atomic number, and the experimental diffusion constants also increase with increasing the atomic number, which is opposite to the Stokes-Einstein (SE) relation. It suggests that alkali metal ions diffuse through a space of 10^-6 m accompanying the hydrated spheres with a time interval of 10^-3 s. For each alkali metal ion, the dynamic ionic radius is evaluated.

SUBMITTER: Hayamizu K

PROVIDER: S-EPMC9033755 | biostudies-literature | 2021 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Dynamic ionic radius of alkali metal ions in aqueous solution: a pulsed-field gradient NMR study.

Hayamizu Kikuko K Chiba Yusuke Y Haishi Tomoyuki T

RSC advances 20210607 33

The dynamic behavior of alkali metal ions, Li+, Na+, K+, Rb+ and Cs+ in aqueous solutions is one of the most important topics in solution chemistry. Since these alkali metals contain nuclear magnetic resonance (NMR) active nuclei, it is possible to directly measure the diffusion constants of the alkali metal ions using the pulsed field gradient (PFG) NMR method. In this paper, the 7Li, 23Na, 87Rb, 133</s ...[more]

PMID: 35479919

Similar Datasets

Project description:The hydration of the alkali metal ions in aqueous solution has been studied by large angle X-ray scattering (LAXS) and double difference infrared spectroscopy (DDIR). The structures of the dimethyl sulfoxide solvated alkali metal ions in solution have been determined to support the studies in aqueous solution. The results of the LAXS and DDIR measurements show that the sodium, potassium, rubidium and cesium ions all are weakly hydrated with only a single shell of water molecules. The smaller lithium ion is more strongly hydrated, most probably with a second hydration shell present. The influence of the rubidium and cesium ions on the water structure was found to be very weak, and it was not possible to quantify this effect in a reliable way due to insufficient separation of the O-D stretching bands of partially deuterated water bound to these metal ions and the O-D stretching bands of the bulk water. Aqueous solutions of sodium, potassium and cesium iodide and cesium and lithium hydroxide have been studied by LAXS and M-O bond distances have been determined fairly accurately except for lithium. However, the number of water molecules binding to the alkali metal ions is very difficult to determine from the LAXS measurements as the number of distances and the temperature factor are strongly correlated. A thorough analysis of M-O bond distances in solid alkali metal compounds with ligands binding through oxygen has been made from available structure databases. There is relatively strong correlation between M-O bond distances and coordination numbers also for the alkali metal ions even though the M-O interactions are weak and the number of complexes of potassium, rubidium and cesium with well-defined coordination geometry is very small. The mean M-O bond distance in the hydrated sodium, potassium, rubidium and cesium ions in aqueous solution have been determined to be 2.43(2), 2.81(1), 2.98(1) and 3.07(1) Å, which corresponds to six-, seven-, eight- and eight-coordination. These coordination numbers are supported by the linear relationship of the hydration enthalpies and the M-O bond distances. This correlation indicates that the hydrated lithium ion is four-coordinate in aqueous solution. New ionic radii are proposed for four- and six-coordinate lithium(I), 0.60 and 0.79 Å, respectively, as well as for five- and six-coordinate sodium(I), 1.02 and 1.07 Å, respectively. The ionic radii for six- and seven-coordinate K(+), 1.38 and 1.46 Å, respectively, and eight-coordinate Rb(+) and Cs(+), 1.64 and 1.73 Å, respectively, are confirmed from previous studies. The M-O bond distances in dimethyl sulfoxide solvated sodium, potassium, rubidium and cesium ions in solution are very similar to those observed in aqueous solution.

Dataset Information

Dynamic ionic radius of alkali metal ions in aqueous solution: a pulsed-field gradient NMR study.

Publications

Dynamic ionic radius of alkali metal ions in aqueous solution: a pulsed-field gradient NMR study.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets