Abstract
The phases, ion crystal packing and thermal properties of the N-alkyl-N-methylpyrrolidinium and piperidinium bis(trifluoromethanesulfonyl) imide (PYR1RTFSI and PIP1RTFSI (subscript R ≤ 1 for methyl and = 2 for ethyl), respectively) salts are compared using powder and single-crystal x-ray diffraction (XRD) and differential scanning calorimetry (DSC). The crystal structure of PIP12TFSI has been determined at 123 K. The salt crystallizes in the triclinic space group with Z ≤ 8. Structural data are also reported for PYR11TFSI at 153 K and PIP 12TFSI at 223 K. PIP11TFSI has identical ion crystal packing to the analogous pyrrolidinium salt PYR11TFSI. Since increasing the cation alkyl chain length to propyl or butyl (R ≤ 3 or 4) reduces the melting point of the salts below room temperature, this study may provide valuable insight into why these pyrrolidinium and piperidinium salts form room-temperature ionic liquids.
Original language | English (US) |
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Article number | 006 |
Pages (from-to) | 10377-10390 |
Number of pages | 14 |
Journal | Journal of Physics Condensed Matter |
Volume | 18 |
Issue number | 46 |
DOIs | |
State | Published - Nov 22 2006 |