Investigation of the role of hydrogen bonding in ionic liquid-like salts with both N- and S-soft donors. Issue 4 (5th December 2022)

• Record Type: Journal Article
• Authors: Renier, Olivier; Bousrez, Guillaume; Smetana, Volodymyr; Mudring, Anja-Verena; Rogers, Robin D.
• Is Part Of: CrystEngComm. Volume 25:Issue 4(2023)
• Page Start: 530
• Page End: 540
• Publication Date: 2022-12-05
• Subjects: Crystals -- Periodicals; Crystal growth -- Periodicals; Crystallography -- Periodicals; Cristaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Cristallographie -- Périodiques; 548
• DOI: 10.1039/d2ce00961g
• Languages: English
• ISSNs: 1466-8033

Abstract

Abstract : Ionic liquid or not: hydrogen bonds such as the relatively rare N–H⋯S hydrogen bond lead in ionic liquid forming ion combinations to higher melting temperatures and lower decomposition points. Abstract : In search of ionic liquids (ILs) with multiple types of soft donor atoms capable of preferentially complexing a range of soft metal ions over harder ions, we investigated structural clues to the role of hydrogen bonding in IL behavior through a series of salts with anions containing both N- and S-donor atoms based on azole thiolates. Reaction of equimolar amounts of triethylamine (Et3 N) or diisobutylamine (DBA) with 1-phenyl-1 H -tetrazole-5-thiol (PhTzSH), 1-methyl-1 H -tetrazole-5-thiol (MeTzSH), or 5-methyl-1, 3, 4-dithiazole-2-thiol (MeDiTSH) yielded [Et3 NH][MeTzS] (1 ), a yellow liquid, and the low melting yellow solids [DBAH][MeTzS] (2 ), [Et3 NH][PhTzS] (3 ), [DBAH][PhTzS] (4 ), [Et3 NH][MeDiTS] (5 ), and [DBAH][MeDiTS] (6 ). Thermal analysis revealed that all of them qualify as ILs with melting points below 100 °C. Single crystal X-ray structure analysis of 2–6 revealed the presence of an extensive H-bonding network that includes the rare N–H⋯S hydrogen bonds in 3, 4, and 6 . These weaker interactions appear to significantly influence thermal behavior, where strong bonding leads to higher melting temperatures and lower decomposition points.