Halide complexes, solvent extraction metals

This is the most common route to vinylidene complexes and occurs in reactions of the 1 -alkynes with metal complexes, preferably with labile neutral or anionic ligands, which give neutral or cationic complexes, respectively. In the latter case, halide is commonly extracted, either by spontaneous displacement by a polar solvent, or by using sodium, silver or thallium salts. 

P-Diketonates. Very strong actinide complexes with p-diketones [An(acac)4 and An02(acac)2] are used in solvent extraction and separation of actinides. They are prepared by direct interaction of the metal or actinyl halide with the appropriate p-diketone in the presence of a base. Only fluorinated An(IV) diketonates produce adducts with Lewis bases, whereas common An02(acac)2 (An = Np, Pu) are stabilized by adduct formation. Fluorinated U02(hfa)2 is a very strong Lewis acid and its adducts with H20 and ROH can be sublimed without decomposition [282],... 

A number of main group and transition metal dithiocarboxylates have been described. They are commonly prepared by metathesis between alkali metal dithiocarboxylates and metal halides. Heavy metal derivatives usually precipitate from aqueous solutions, but are soluble in organic solvents and can be solvent extracted. The alkali metal, ammonium, phosphonium, and arsonium salts are water soluble.300 The composition of metal complexes is sensitive to preparation conditions and is frequently pH dependent. 

Basic dyes (triphenylmethane, xanthene, azine, etc., dyes) form ion-association compounds (ion-pairs) with anionic halide complexes of metals and non-metals e.g., SbCl, AuBr4 , TaFe , BF4 ). The resulting compounds, that may be extracted into non-polar organic solvents, may serve as a basis for sensitive spectrophotometric methods [62-65]. 

This methodology enjoys the merits of other approaches and exhibits several additional advantages 1) it has proven applicable to a wide range of transition metal and main group oxides 2) the metal precursors studied so far are readily available, being either alkoxide or halide complexes 3) in many cases, syntheses can be run in alcoholic solvents in essentially nonhydrolytic conditions, which aids in controlling hydrolysis and condensation rates 4) the critical micelle concentrations required for polyethylene-oxide-polypropylene-oxide di- and triblock copolymers are usually much lower than the concentrations needed for ionic surfactants and 5) because of the neutral, nonaqueous conditions used in these preparations, control of pH is not required, and the surfactant can be removed from the mesostructured material by calcination or milder solvent extraction methods with nonpolar solvents. 

One field of using coordination chemistry approaches is the solvent extraction of halide complexes of metals. 

Zolotov,Yu.A. Iofa,B.Z. Chuchalin,L.K. Solvent Extraction of Metal Halide Complexes Nauka Publishing House Moscow, 1973 (in Russian). 

The above characterizations primarily concern the interactions between molecular solutes and ILs. However, ILs are also good solvents for ionic compounds, and have been studied extensively as media for transition metal catalysis [4, 38, 219] and for the extraction of heavy metals [23]. ILs are capable of solvating even simple salts, such as NaCl, to some degree [219], and in fact the removal of halide impurities resulting from synthesis can be a considerable challenge [68]. However, ionic complexes are generally far more soluble than simple salts [220], and we focus our attention on these systems as they have received greater study and are more relevant to the processes noted above. 

The allylmagnesium halide in ether is slowly added to a suspension or solution of the metal halide at 0°C or lower. Addition at low T improves yields and is essential for the synthesis of thermally unstable, homoleptic allyl complexes. The complexes are isolated by evaporation of the reaction mixture and extraction into an aromatic or alkane solvent. Purification is effected by crystallization or sublimation. When stable allyl compounds are prepared, an aqueous wash of the reaction mixture can be used to remove Mg salts and xs RMgX or -Li reagent the crude products can then be isolated from the resultant organic layer. 

The most generally applicable method of forming the transition- and inner transition-metal 7t-cyclopentadienyl bond involves the reaction of Na[Cp] with the appropriate anhydrous metal halide or complex halide in an ethereal solvent such as THF or glyme under a dry, inert atmosphere. The complexes are usually isolated by evaporation of the solvent and extraction into an aromatic or aliphatic hydrocarbon solvent. Purification is achieved by crystallization or sublimation. 

The oil sample (approximately 0.3 g) is dispersed in a hydrocarbon solvent and reacted with a mixture of metallic s um catalyzed with naphthalene and diglyme at ambient temperature. This process converts organic halogens to their respective sodium halides. Halides in the treated mixture, including those present prior to the reaction, are then extracted into an aqueous buffer, which is then titrated with mercuric nitrate using diphenyl carbazone as the indicator. The end point of the titration is the formation of the blue-violet mercury diphenylcarbazone complex. 

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