Ionic water-stable

Mary s University in Halifax, Nova Scotia. He was a visiting professor at the U.S. Air Force Academy in 1991, where he first prepared many of the water-stable ionic liquids popular today. 

Despite the utility of chloroaluminate systems as combinations of solvent and catalysts in electrophilic reactions, subsequent research on the development of newer ionic liquid compositions focused largely on the creation of liquid salts that were water-stable [4], To this end, new ionic liquids that incorporated tetrafiuoroborate, hexafiuorophosphate, and bis (trifiuoromethyl) sulfonamide anions were introduced. While these new anions generally imparted a high degree of water-stability to the ionic liquid, the functional capacity inherent in the IL due to the chloroaluminate anion was lost. Nevertheless, it is these water-stable ionic liquids that have become the de rigueur choices as solvents for contemporary studies of reactions and processes in these media [5],... 

We have also demonstrated that well-behaved quantized charging of gold MPCs is possible in air- and water-stable room-temperature ionic liquids, such as 1-hexyl-3-methylimidazolium tris(penta-fluoroethyl)-trifluorophosphate (HMImEEP), Fig. 30c, d [334, 335]. As ionic liquids have very attractive features, including nearzero vapor pressure, considerable thermal stability, and an electrochemical stability window that often exceeds 4 V, this demonstration is particularly significant from a technological point of view. 

Wilkes, J. S. Zaworotko, M. J. Air and water stable l-ethyl-3-methyhmidazolium based ionic liquids, J. Chem. Soc., Chem. Commun., 1992, 965-967. 

The typical liquid clathrate is characterized by (a) a low viscosity relative to that of a neat ionic liquid, (b) immiscibility with excess aromatic solvents, and (c) non-stoichiometric compositions. The formation of air- and water-stable liquid clath-rates has been reported for the compositions consisting of aromatic hydrocarbons (e.g., benzene, toluene, and xylenes) and common salts of [AMIM] cation with the anions PF, [Tf2N] , BFJ, and Cl 91). 

Endres, E and El Abedin, S.Z., Air and water stable ionic liquids in physical chemistry, Phys. Chem. Chem. Phys., 8,2101, 2006. 

Nikitenko, S.I., Moisy, Ph., Formation of higher chloride complexes of Np(IV) and Pu(IV) in water-stable room-temperature ionic liquid [BuMeIm][Tf2N], Inorg. Chem., 45,1235-1242,2006. 

Endres, R, El Abedin, S.Z., Borissenko, N., Probing lithium and alumina impurities in air- and water stable ionic liquids by cyclic voltammetry and in situ scanning tunneling microscopy, Zeits. Phys. Chem.—Int. ]. Res. Phys. Chem. Chem. Phys., 220, 1377-1394, 2006. 

The chloroaluminate ionic liquids are water sensitive. When you expose them to air, they produce HCl. The tetrafluoroborates and hexafluorophosphates, on the other hand, are air and water stable. They can be worked with in an open beaker. Because they are nonvolatile, there is no smell, and they can be used in high-vacuum systems. 

The reaction of l- -butyl-3-methylimidazolium chloride (BMIC) with sodium tet-rafluoroborate or sodium hexafluorophosphate produced the room temperature-, air-and water-stable molten salts (BMr)(BF4 ) and (BMTXPFg ), respectively in almost quantitative yield. The rhodium complexes RhCKPPhjls and (Rh(cod)2)(BF4 ) are completely soluble in these ionic liquids and they are able to catalyze the hydrogenation of cyclohexene at 10 atm and 25°C in a typical two-phase catalysis with turnovers up to 6000 (see fig. 6.10). 

Chauvin and Olivier-Bourbigou (123) classified ionic liquids according to the complexing ability of their anions because they influence the solvation and complexing ability of ionic liquids. One problem is the instability of several ionic liquids in water, which reduces their potential for application in catalytic reactions. This subject is under investigation, and a series of novel air- and water-stable low-melting salts has recently been prepared (124). 

Recently, the air- and water-stable combinations of l-n-butyl-3-methyl-imidazolium chloride with sodium tetrafluoroborate or sodium hexafluoro-phosphate have been prepared. The rhodium complexes [RhCl(PPh3)3] and [Rh(COD)2](BF4) are completely soluble in these ionic liquids and catalyze the hydrogenation of cyclohexene in a typical two-phase reaction with numbers of turnovers of up to 6000 (131). 

In the 1990s John Wilkes and coworkers introduced air- and water-stable ionic liquids (see Chapter 2.2) which have attractive electrochemical windows (up to 3 V vs. NHE) and extremely low vapor pressures. Furthermore, they are free from any aluminum species per se. Nevertheless, it took a while until the first electrodeposition experiments were published. The main reason might have been that purity was a concern in the beginning, making reproducible results a challenge. Water and halide were prominent impurities interfering with the dissolved metal salts and/or the deposits. Today about 300 different ionic liquids with different qualities are commercially available from several companies. Section 4.2 summarizes the state-of-the-art of electrodeposition in air- and water-stable ionic liquids. These liquids are for example well suited to the electrodeposition of reactive elements such as Ge, Si, Ta, Nb, Li and others. 

Electrodeposition of Metals in Air- and Water-stable Ionic Liquids... 

Chloroaluminate ionic liquids are regarded as the first generation of ionic liquids. However, their hygroscopic nature has delayed progress in many applications since they must be prepared and handled under an inert gas atmosphere. Thus, the synthesis of air- and water-stable ionic liquids, which are considered as the second and third generations of ionic liquids, has attracted further interest in the use of ionic liquids in various fields. Unlike the chloroaluminate ionic liquids, these ionic liquids can be prepared and safely stored outside an inert atmosphere. Generally, they are water insensitive. However, water-containing [BMIM]PF< can... 

The electrodeposition of silver from chloroaluminate ionic liquids has been studied by several authors [45-47], Katayama et al. [48] reported that the room-temperature ionic liquid l-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM]BF4) is applicable as an alternative electroplating bath for silver. The ionic liquid [EMIM]BF4 is superior to the chloroaluminate systems since the electrodeposition of silver can be performed without contamination of aluminum. Electrodeposition of silver in the ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) and l-butyl-3-methylimidazoliumhexafluorophosphate was also reported [49], Recently we showed that isolated silver nanoparticles can be deposited on the surface of the ionic liquid Tbutyl-3-methylimidazolium trifluoromethylsulfonate ([BMIMJTfO) by electrochemical reduction with free electrons from low-temperature plasma [50] (see Chapter 10). This unusual reaction represents a novel electrochemical process, leading to the reproducible growth of nanoscale materials. In our experience silver is quite easy to deposit in many air- and water-stable ionic liquids. 

Antimony is a brittle silvery-white metal. Although the unalloyed form of antimony is not often used in industry, alloys of antimony have found wide commercial applications. The integration of antimony gives certain desirable properties, such as increased corrosion resistance and hardness. Moreover, antimony is also the component of some semiconductors such as InSb and InAsi %Sb%. Sb electrodeposits with good adherence were obtained in a water-stable l-ethyl-3-methylimidazolium chloride-tetrafluoroborate ([EMIM]C1-BF4) room-temperature ionicliquid [53]. Furthermore, it was stated that a crystalline InSb compound can be obtained through direct electrodeposition in the ionic liquid [EMIM]C1-BF4 containing In(III) and Sb(III) at 120 °C [54]. It is just a question of time until antimony electrodeposition is reported in the third generation of ionic liquids. 

In this section we will show that air- and water-stable ionic liquids can be used for the electrodeposition of highly reactive elements which cannot be obtained from aqueous solutions, such as aluminum, magnesium and lithium, and also refractory metals such as tantalum and titanium. Although these liquids are no longer air-and water-stable when AICI3, TaFs, TiCU and others are dissolved, quite interesting results can be obtained in these liquids. 

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