1-Ethyl-3-methylimidazolium Based Ionic Liquids Containing Cyano Groups:  Synthesis, Characterization, and Crystal Structure

Abstract

New 1-ethyl-3-methylimidazolium (EMI) salts [EMI][C(CN)3] and [EMI][Ag(CN)2] were prepared and characterized. The C(CN)3 salt has a melting point at -11 degrees C and shows a low viscosity (18 cP) and a high ionic conductivity (1.8 x 10(-2) S cm(-1)) at room temperature. This conductivity is less than that of [EMI][N(CN)2] salt (2.7 x 10(-2) S cm(-1)), possibly due to the larger molecular weight of the anion. The first EMI salt containing Ag(I) complexes [EMI][Ag(CN)2] has a higher melting point of 73 degrees C. In the crystal, the C-H...pi interionic interactions between cations construct zigzag chains in the cationic two-dimensional layer. Close Ag..Ag interionic contacts of 3.226(1) A were observed in the one-dimensional anionic chain, and the relatively high melting point among the EMI salts with a monoanion appears to be governed essentially by these direct Ag...Ag interactions.

Application of Ionic Liquids Containing Tricyanomethanide [C(CN)3]− or Tetracyanoborate [B(CN)4]− Anions in Dye-Sensitized Solar Cells

“…There are only a limited numbers of ILs that contain [C(CN) 3 ] − and [B(CN) 4 ] − anions and their applications have been scarcely explored, despite the high stability and interesting electrochemical and physicochemical properties of the [B- (CN) 4 ] − anion. 10 Indeed, in nearly all of the applications, including electrolytes, 11−13 as well as others, 14,15 studies are almost exclusively on the [EMI] + -based systems.…”

“…Sodium tricyanomethanide Na[C(CN) 3 ] and potassium tetracyanoborate K[B(CN) 4 ] were received as a gift from Lonza AG and from Merck KGaA, respectively. IR spectra were recorded on a Perkin-Elmer FT-IR 2000 system.…”

“…IR spectra were recorded on a Perkin-Elmer FT-IR 2000 system. NMR spectra were measured on a Bruker DMX 400, using Me 4 Si as an external standard. Electrospray ionization mass spectra (ESI-MS) were recorded on a ThermoFinnigan LCQ Deca XP Plus quadrupole ion trap instrument using a literature method.…”

“…3 In contrast, ILs based on nonfluorous anions, i.e., tricyanomethanide ([C-(CN) 3 3 ] (where EMI = 1-ethyl-3-methylimidazolium cation) has a viscosity of 18 cP at 22°C and a melting point of 11°C, 4 4 ] has a viscosity of 19 cP at 21°C, 8 both being lower than that of [EMI][Tf 2 N], 27 cP at 20°C.…”

“…The appropriate imidazolium, pyridinium, pyrrolidinium, or ammonium halide was mixed with Na[C(CN) 3 ] or K[B(CN) 4 ] in a molar ratio of 1:1 in water (5 mL). After stirring at room temperature for 24 h, the reaction mixture was extracted with dichloromethane (3 × 10 mL).…”