Tetrahalidometallate(II) Ionic Liquids with More than One Metal: The Effect of Bromide versus Chloride

Abstract

Fifteen N-butylpyridinium salts -five monometallic [C 4 Py] 2 [MBr 4 ] and ten bimetallic [C 4 Py] 2 [M 0.5 a M 0.5 bBr 4 ] (M=Co, Cu, Mn, Ni, Zn) -were synthesized, and their structures and thermal and electrochemical properties were studied. All the compounds are ionic liquids (ILs) with melting points between 64 and 101 °C. Powder and single-crystal X-ray diffraction show that all ILs are isostructural. The electrochemical stability windows of the ILs are between 2 and 3 V.The conductivities at room temperature are between 10 À 5 and 10 À 6 S cm À 1 . At elevated temperatures, the conductivities reach up to 10 À 4 S cm À 1 at 70 °C. The structures and properties of the current bromide-based ILs were also compared with those of previous examples using chloride ligands, which illustrated differences and similarities between the two groups of ILs.

Mixed chloridometallate(ii) ionic liquids with tunable color and optical response for potential ammonia sensors

“…The crystal structures are closely related to the existing examples 23,28,33,42 and these data clearly show that the process and approach towards these ILs is highly reproducible, exible, and adaptable. Moreover, like on the previous examples, all structures of the single crystals (Fig.…”

“…Indeed, Balischewski et al have recently shown that the combination of two or three metal ions in MX 4 2− -based ILs leads to ILs with a range of colors from blue to green to yellow and orange, although no tests on their sensing capabilities have been made so far. 23,28 The current article extends the previous work in two directions: (1) it expands the pool of mixed d-metal-based ILs to new bimetallic ILs built around Ni(II) and Zn(II) and (2) the article also demonstrates that the compounds can be used as the active component in an optical setup for the detection of ammonia gas using a ber optic probe and a simple IL-coated glass slide.…”

“…[17][18][19] Moreover, also the exchange of the X − anion directly affects the properties of the resulting IL. [20][21][22][23] One of the striking features of these tetrahalidometallate compounds (both their complexes and their ILs) is their intense color and color change upon exchange of a cation or ligand in the MX 4 2− unit. MX 4 2− based compounds also show a strong solvato-or vapochromism, 24,25 suggesting applications in gas or solvent sensing.…”

“…17–19 Moreover, also the exchange of the X − anion directly affects the properties of the resulting IL. 20–23…”

“…Indeed, Balischewski et al have recently shown that the combination of two or three metal ions in MX 4 2− -based ILs leads to ILs with a range of colors from blue to green to yellow and orange, although no tests on their sensing capabilities have been made so far. 23,28…”