Water halides

Among the potential impurities in ionic liquids water, halide ions and organic starting material are of great importance for transition metal chemistry while the colour of an ionic liquid is not a critical parameter in most applications. 

Numerous d cobalt(III) complexes are known and have been studied extensively. Most of these complexes are octahedral in shape. Tetrahedral, planar and square antiprismatic complexes of cobalt(lII) are also known, but there are very few. The most common ligands are ammonia, ethylenediamine and water. Halide ions, nitro (NO2) groups, hydroxide (OH ), cyanide (CN ), and isothiocyanate (NCS ) ions also form Co(lII) complexes readily. Numerous complexes have been synthesized with several other ions and neutral molecular hgands, including carbonate, oxalate, trifluoroacetate and neutral ligands, such as pyridine, acetylacetone, ethylenediaminetetraacetic acid (EDTA), dimethylformamide, tetrahydrofuran, and trialkyl or arylphosphines. Also, several polynuclear bridging complexes of amido (NHO, imido (NH ), hydroxo (OH ), and peroxo (02 ) functional groups are known. Some typical Co(lll) complexes are tabulated below ... 

Table 6.2 shows the detachment energy of one water molecule from a hydrated halide ion cluster [41]. The strength of the water-halide interactions is reduced as the ionic radius increases in the order of Fspecific adsorption in an electrochemical environment. It is clear that the nonspecific adsorption behavior of F is due to its strongly bound solvation shell. Due to... 

Impurities, such as water, halides, unreacted organic salts, and organics, easily accumulate in ionic liquids [15] and may influence their solvent properties [3, 16] and/or interfere with the biocatalyst. For example, small amounts of chloride ion caused a severe deactivation of two lipases [17]. The irreproducibility of some early... 

Ether Hydrogen Two alkyl halides Water halide... 

When ILs were first commercially available, the quality of most samples was questionable as they contained numerous organic and inorganic impurities. More recently different quality levels have been introduced (for synthesis, high purity, ultrapurity). Ultrapure ionic liquids usually contain water, halide and metal ion impurities below 10 ppm and they are currently the best choice for fundamental physicochemical studies. 

Divided cells — Electrochemical cells divided by sintered glass, ceramics, or ion-exchange membrane (e.g., - Nafion) into two or three compartments. The semipermeable separators should avoid mixing of anolyte and - catholyte and/or to isolate the reference electrode from the studied solution, but simultaneously maintain the cell resistance as low as possible. The two- or three-compartment cells are typically used a) for preparative electrolytic experiments to prevent mixing of products and intermediates of anodic and cathodic reactions, respectively b) for experiments where different composition of the solution should be used for anodic and cathodic compartment c) when a component of the reference electrode (e.g., water, halide ions etc.) may interfere with the studied compounds or with the electrode. For very sensitive systems additional bridge compartments can be added. 

Ruthenium(III), d5 Ru111 is often associated with classical-type ligands, e.g. ammine, water, halides. They are octahedral low spin t2/ species with one unpaired electron and generally sub-stitutionally inert. The electronic structure of polynuclear carboxylates and mixed valence Ru" 1" complexes of the type [Ru(NH3)5]2L5+ has been the subject of much interest particularly with respect to the degree of unpaired electron delocalization within these molecules. 

The solubility of most alkyl halides in water is very low, unless some solubilizing group happens to be present (e.g., -OH, -CO2H). Hence, most reaction systems have involved three separate phases (water, halide, metal substrate), with all the accompanying complications. 

Granite magmas are often rich in volatile compounds (e.g., water, halides, carbonates, alkalis) that tend to accumulate as residual fluids as these magmas solidify. Some granites show steep increases in heaviest lanthanide abundances as a result of interactions with hydrothermal fluids, either associated with their formation or as a result of later interactions (e.g., Kazakhstan massif, Mineyev, 1963 Nigeria, Aleksiyev, 1970 and Bowden and Whitley, 1974). 

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