The thermal decomposition of Samarium-Thiocyanate-Based ionic liquids

Tsion Ohaion-Raz, Smadar Attia, Natalie Kostyria, Yeshayahu Ben-Eliyahu

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


New lanthanide containing ionic liquids (ILs) based on thiocyanate complexes of the type [BMIM]x-3[Ln(NCS)x(H2O)y] (BMIM = 1-Butyl-3-Methylimidazolium; x = 6,7,8; y = 0–2, x + y < 10; Ln = Y, La-Yb) have been reported in recent studies. These complexes are highly efficient in dissolving lanthanide complexes within ILs. The present work includes a thermal decomposition study of the anhydrous ionic liquids of this type with Samarium cation as the lanthanide. The thermal decomposition of [BMIM][NCS], [BMIM]3[Sm(NCS)6], [BMIM]4[Sm(NCS)7] and [BMIM]5[Sm(NCS)8] was investigated by employing a combination of thermo-gravimetric analysis (TGA), and temperature programmed desorption (TPD) coupled with mass spectrometry. The decomposition temperature of the samarium-containing ILs were found to be higher than that measured for [BMIM][NCS], suggesting stabilization of the ILs by complexation to the samarium cation. Thermal gravimetric analysis of [BMIM]x-3[Sm(NCS)x] confirms that the thermal decomposition occurs in a stepwise fashion to give Sm(NCS)3 via a [BMIM]3[Sm(NCS)6] intermediate, whereby [BMIM][NCS] units are decomposed to give gaseous products. Additional experimental evidence obtained with TPD-MS supporting this decomposition route and reveal that each [BMIM][NCS] unit decomposes by the rapid nucleophilic attack of the thiocyanate anion at the C-N bond of the methyl- and butyl- imidazole groups, and their proposed reaction mechanism are introduced here.

Original languageEnglish
Article number117143
JournalJournal of Molecular Liquids
StatePublished - 15 Oct 2021
Externally publishedYes


  • Lanthanides
  • RTIL
  • Thermal decomposition

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Spectroscopy
  • Physical and Theoretical Chemistry
  • Materials Chemistry


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