Lower Oxidation States of f Elements: I. Preparation and Identification of Actinides and Lanthanides in Lower Oxidation States

About low oxidation states, hydration and covalence properties of f elements

“…The usual logarithmic transform of the waves corresponds to 30 mV and, therefore, since diffusion process is observed, two electrons are involved in the electrochemical reaction. But a more definitive argument was drawn which is not taking into account in the cited recent review [1]. By comparing the waves with complexing agent (citrate) and non complexing solution (lithium perchlorate as well as chloride supporting electrolyte) it has been shown that the waves are shifted, after addition of citrate ions with the same amplitude: 80-100 mV as observed for divalent species: Ba 2+ , Eu 2+ , Mn 2+ [22,27].…”

“…By using simple reaction of lithium amalgam on citric actinide solutions [9], it is true that pH of the solution and potential amalgam/solution is changing during the experiment and possibility of hydrolysis of actinide ions was not excluded as discussed [1]. However, when experiments were realized using electrochemical method [11,12] it was shown that experimental parameters (pH, potential of the electrode) were maintained essentially constant during the electrolysis.…”

“…We can also remark that the test used to elucidate the mendelevium adsorption mechanism is to consider the dependence of the distribution D between the liquid and solid phases with the concentrations of the macro component anion [A − ] [1]. It was postulated that D should be constant vs. [A − ] for monovalent ions and proportional to [A − ] for divalent ions.…”

“…It has been often discussed in the literature. For instance the question of appearance of oxidation states lower than three have been again recently discussed by Mikheev et al in three papers [1][2][3]. Since many researches have been devoted to these questions, sometimes showing discrepancies, it is necessary to consider these reduction properties even if data have been reported several decades ago.…”

Microemulsion approach to neodymium, europium, and ytterbium oxide/hydroxide colloids—Effects of precursors and preparation parameters on particle size and crystallinity

“…Although the initial oxidation state of +III is the preferred state for the investigated elements, it is known that especially Eu and Yb can form relatively stable solutions in their bivalent forms [25]. In order to study the metal ion oxidation state, the samples of the "ClSDS" series were subjected to XANES measurements.…”