Anion dependent ion pairing in concentrated ytterbium halide solutions

Area of Science:

• Solution chemistry
• Spectroscopy
• Coordination chemistry

Background:

• Understanding ion pairing in aqueous solutions is crucial for various chemical and biological processes.
• Ytterbium halides are relevant in diverse applications, necessitating detailed studies of their solution behavior.

Purpose of the Study:

• To investigate the ion pairing and hydration structures of ytterbium chloride (YbCl3) and ytterbium bromide (YbBr3) in aqueous solutions.
• To determine the influence of halide anions (Cl- vs. Br-) on the local hydration environment of ytterbium ions (Yb3+).

Main Methods:

• Terahertz (THz) spectroscopy (30-400 cm-1) was employed to probe the vibrational dynamics and hydration structures.
• Raman spectroscopy was used as a supplementary technique to confirm findings.

Main Results:

• THz spectra revealed fundamental differences in hydration structures between YbCl3 and YbBr3 at high salt concentrations.
• No evidence of altered local hydration environments was observed for YbBr3 within the studied concentration range.
• Spectra of YbCl3 indicated the formation of weak contact ion pairs, suggesting anion-specific interactions.

Conclusions:

• Anion specificity plays a significant role in the ion pairing of ytterbium halide solutions.
• The hydration structure around Yb3+ is influenced differently by chloride and bromide anions.
• Weak contact ion pair formation is characteristic of YbCl3 solutions under high concentration conditions.