Syntheses and Structures of the First Lanthanide–Thiosulfate Complexes and the Subsequent Formation of Mixed Thiosulfate–Sulfite Compounds

Abstract

The first rare-earth (RE) thiosulfate complexes, RE­(S2O3)6 9–, have been crystallized via room-temperature reactions and structurally characterized through single-crystal X-ray diffraction. The incorporation of KCl was essential to their successful crystallization. Then through the use of both solvent-layering and heating techniques, these complexes can undergo structural changes through breaking the thiosulfate S–S bond and forming the sulfite anion (SO3 2–). Using the former approach, two novel lanthanide mixed thiosulfate–sulfite compounds were synthesized; moreover, through the addition of low-temperature heating time, a new structure with a higher proportion of sulfite to thiosulfate was produced. These syntheses and techniques open the door to a new family of unexplored complexes containing hard lanthanide cations and soft thiosulfate anions. The 23 compounds discussed herein show how simple changes to the synthetic process illuminate manipulatable redox reactions able to produce unique rare-earth thiosulfate materials.

Crystal structure of sodium thiosulfate dihydrate and comparison to the pentahydrate

“…One of the most characteristic features of the thiosulfate anion is the enhanced reactivity including changes of the sulfur oxidation state, which hampered the preparation of pure compounds. For example, the synthesis of pure thiosulfuric acid succeeded just lately via the reaction of Na 2 S 2 O 3 and anhydrous HF (Hopfinger et al, 2018), and the first pure thiosulfate complexes of lanthanides were characterized very recently (Dalton et al, 2021).…”