Hydration of Oxometallate Ions in Aqueous Solution

Abstract

The strength of hydrogen bonding to and structure of hydrated oxometallate ions in aqueous solution have been studied by double difference infrared (DDIR) spectroscopy and large-angle X-ray scattering (LAXS), respectively. Anions are hydrated by accepting hydrogen bonds from the hydrating water molecules. The oxygen atom of the permanganate and perrhenate ions form weaker and longer hydrogen bonds to water than the hydrogen bonds in bulk water (i.e., they act as structure breakers), while the oxygen atoms of the chromate, dichromate, molybdate, tungstate, and hydrogenvanadate ions form hydrogen bonds stronger than those in bulk water (i.e., they act as structure makers). The oxometallate ions form one hydration shell distinguishable from bulk water as determined by DDIR spectroscopy and LAXS. The hydration of oxoanions results in X–O bond distances ca. 0.02 Å longer than those in unsolvated ions in the solid state not involved in strong bonding to counterions. The oxygens of oxoanions with a central atom from the second and third series in the periodic table and the hydrogenvanadate ion hydrogen bind three hydrating water molecules, while oxygens of oxoanions with a heavier central atom only form hydrogen bonds to two water molecules.

Pair distribution function and 71Ga NMR study of aqueous Ga3+ complexes

“…As the pH is measured to be approximately 0 for the R = 0 solutions (except for the Ga 2 (SO 4 ) 3 solution due the base properties of the anion) hydrolysis must occur as of the solvent or breaking of the dimer in the octahedral region. Additional ions are known to affect the bulk water structure, 2,43 and they would likely results in a less ordered structure around Ga 3+ .…”

“…2 However, one should remember that the ion concentration increases with increasing R-values. As ions are known to affect the bulk water structure 2,43 this may affect the solvent ordering around the Ga 3+ ions, and thereby partly explain the observed differences between aqueous octahedral an tetrahedral Ga 3+ species.…”

Guanidinium-Based Ionic Covalent-Organic Nanosheets for Sequestration of Cr(VI) and As(V) Oxoanions in Water

“…The impacts of steric and electrostatic modulations on the ability of iCONs to selectively adsorb chromate and arsenate were briefly examined in the presence of an interfering oxoanion. Sulfate and phosphate were selected as two representative interfering oxoanions for chromate and arsenate, respectively, due to the similarity in size, hydration energy, and p K a values. − The equilibrium Cr­(VI) and As­(V) uptakes ( Q e ′) were measured in the binary solutions of chromate–sulfate (CrO 4 -SO 4 ) and arsenate–phosphate (AsO 4 -PO 4 ), respectively, which contain the same concentration of both the target and interfering oxoanions. The effectiveness of selective uptake was evaluated with the ratio ( Q e ′/ Q e ) of the equilibrium uptake values in the dual oxoanion systems versus the single oxoanion system under the same conditions (see the Experimental Section for details).…”

Fusion-Based Neutron Generator Production of Tc-99m and Tc-101: A Prospective Avenue to Technetium Theranostics

“…This behaviour is particularly apparent in acidic pHs where an assortment of anionic polymolydates with varying degrees of hydration and charge densities, and even cationic or neutral species, can (co)exist [53][54][55]. In solution, polyanionic Mo species, such as [MoO 4 ] 2− , are known to form hydrogen bonds stronger than in the surrounding bulk water, classifying them as cosmotropic in nature [56]. It has been shown that Mo adsorption on AC under static conditions is pH dependent, and once again is dictated by the surface charge of AC and the dominant species of Mo in solution [57][58][59][60] ), the interaction of Mo with AC is electrostatically favoured; AC surface functionalities described in the previous paragraph also apply here.…”