Absorbance metal chloride complexes

The absorbance of metal chloride complexes in the ultraviolet spectrsil region has been used extensively to automatically detect metal ions in liquid chromatography [24-27], The absorption wavelength maxima of the metal chloride complexes are shown in Table 4.3. Metal EDTA complexes also absorb quite well. 

K bromide solns v si sol in w. It occurs in nature as the mineral born silver and is formed when a soln of a sol chloride is added to a soln of a Ag salt. Silver chloride in contact with metallic Na or K is exploded by percussion (Ref 3). Its ammoniacal soln absorbs acetylene, forming Silver Acetylide Chloride complexes which are expl (See Vol 1, p A80 l. Silver chloride is used in medicine as an antiseptic nerve sedative, in the manuf of pure Ag Ag salts, and in photography photometry(Refs... 

The metals form complex cyanides in which they are covalently bonded to the radical, e.g. KM(CN)2. All complex with ammonia to give the ion [M(NHg)2] and there are similar substituted ammonia and pyridine complexes. Copper(I) chloride dissolved in HCl absorbs CO, and the hydrated carbonyl derivative, Cu(CO)Cl.H20, has been recovered from the solution. A gold analogue is known. Copper(I) and silver solutions also absorb ethylene and substitued ethylenes. Manometric measurements (Vestin, 1954) have shown that two distinct complexes are formed by acetylene in HCl solution, C2H2(CuCl)g and C2H2(CuCl)2. 

Procedure. To 10.0 mL of the solution containing up to 200 fig of copper in a separatory funnel, add 5.0 mL of 10 per cent hydroxylammonium chloride solution to reduce Cu(II) to Cu(I), and 10 mL of a 30 per cent sodium citrate solution to complex any other metals which may be present. Add ammonia solution until the pH is about 4 (Congo red paper), followed by lOmL of a 0.1 per cent solution of neo-cuproin in absolute ethanol. Shake for about 30 seconds with 10 mL of chloroform and allow the layers to separate. Repeat the extraction with a further 5 mL of chloroform. Measure the absorbance at 457 nm against a blank on the reagents which have been treated similarly to the sample. 

Ln-Halides. The complexation/solvation criteria is just one reason why lanthanide halides are the most common precursors in organolanthanide chemistry. In this evaluation, lanthanide iodides are often preferred to bromides and chlorides, however the former are more difficult to synthesize and are much more expensive [96f. Waterfree, solid Ln-halides are ionic substances with high melting points which immediately absorb water when exposed to air, forming hydrates (I > Br > Cl ). Therefore, they have to be handled under an inert gas atmosphere. The main use of the halides is for the production of pure metals [96]. Some methods of preparing Ln(III)-chlorides are summarized in Scheme IV [96],... 

For metal-humic acids complexes solubilization, 5 g of finely powdered sediment dried at 45°C are shaken with 0.1 M acetic acid and the treatment is repeated until the carbonates are completely removed. After centrifugation and washing with water, 0.5 M NaOH (degassed with N2) is added and shaken for 24 hr in order to extract the complexes. The extraction is repeated with a fresh 0.5 M NaOH solution and the two extracts are combined. The resulting alkaline solution is filtered through a 0.45 pm Millipore filter and analyzed by ICP-AES. After purification of the extracted humic acids by precipitation and redissolution, they are extracted into chloroform by means of cetylpiridinium chloride and NaCl. The absorbance of the chloroform extract at 450 nm is then measured to determine the concentration of humic acids (51). 

The selectivity of spectrophotometric methods has been greatly increased by the development of derivative spectrophotometry (see Chapter 1.5). Derivative spectrophotometry enables one to single out, by means of various mathematical algorithms of data processing, a separate signal due to a selected component, from the sum of absorbances of the analysed mixture. This technique was successfully applied in determinations of a number of elements in mixtures such as Pd, Pt and Au [37], Pd and Pt in iodide solutions [38], Au, Pd and Pt in bromide solutions [39], Ru(IIl) and Rh(IIl) in the form of octadecyldithiocarbamate complexes [40], Ru and Os in chloride solutions [41], Cu, Hg and Pb as dithizonates [42], complexes of various metals with 4-(2-pyridylazo)resorcinol [43], Fe(IIl) with EDTA in the presence of Cr(III), A1 and Mn [44], Cr(III) and Cu(II) with EDTA [45], and Cu and Co in a flow system [46]. Derivative spectrophotometry was also used in the study of Sr- complexing reactions with various crown ethers [47]. 

It was later found that certain metal halides or ions other than Pt11, notably Cu1, Ag1, Hg11 and Pd11, formed complexes when treated with a variety of olefins. Thus cuprous chloride in aqueous suspension absorbs ethylene, both components dissolving well beyond their normal solubilities and in a 1 1 mole ratio. Solid cuprous halides also absorb some gaseous olefins, but the dissociation pressures of the complexes are quite high. The reaction of silver ions especially, with a variety of unsaturated substances, has been studied by physical measurements such as distribution equilibria between an aqueous and an organic solvent phase. The results can be accounted for in terms of equilibria of the type... 

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