Indium complexes hydroxides

A study of the species present in these solutions and the mechanism of the deposition has been presented [71]. Under the conditions of the depositions, the main solution indium species (in the absence of thioacetamide) are In-Cl (mainly [InCU] ) complex species. Only ca. 1% of the total In content is present as free In. No ln(OH)3 or hydroxy-complexes were calculated to be present if acetic acid was present (in the absence of acetic acid, the hydroxide could form). From a kinetic analysis of the deposition reaction, it was concluded that the deposition occurred by direct reaction between the thioacetamide and the chloro-indium complexes. It was noted that thioacetic acid was the main by-product and that no acetamide was detected (see 8ec. 3.2.1.3 for a description of the possible mechanisms and by-products of thioacetamide hydrolysis). Acetonitrile (CH3CN), a less common by-product, was also detected at the higher pH values (these depositions took place between a pH of 2 and 3) but not at the lower ones. 

In the report that described the synthesis of 108 (777), Whitmire also observed that the reaction between NaBi03 and methanolic [Fe(CO)s] in the presence of hydroxide afforded the trianionic species [Bi Fe(CO)4 4]3, 110, which was subsequently characterized by X-ray crystallography (775). Cluster 110 contains a central bismuth atom tetrahedrally coordinated by four Fe(CO)4 fragments and is isoelectronic with the anionic tetracobalt-indium complex, 27, and the neutral tetracobalt-germanium, - tin, and -lead complexes, 68, 71, and 72. Oxidation of 110 affords 108 (777), while acidification (772) yields the hydride-containing cluster [BiFe3(CO)9(/i-H)3], 111, which also contains a tetrahedral BiFe3 core. Johnson and Lewis (114) have... 

The kinetics in the basic media are summarised in the table. Since the rate is not affected by the buffer under due conditions, the reaction mechanism seems to involve essentially that of hydroxo complexes except for thallium, and the attack of hydroxide ions upon the complex appears to play an important role. The fact that the rate of the indium complex is proportional to the square of the hydroxide ion concentration tells that indium is the most inert among the three. Such an inertness of indium complexes may be reflected in the small value of its apparent dissociation constant of the coordinated water molecule, K. ... 

Porphyrin, octaethyl-, indium hydroxide complex cyclic voltammetry, 4, 399 <73JA5140)... 

Several other examples of porphycene complexes with trivalent metals have also appeared in the literature.3.4.12,29,29-32 These include the aluminum(III) complexes 3.75a-d and 3.76, as well at the manganese(III), cobalt(III) iron(III), indium(III), and gallium(III) complexes 3.77-3.81 (Figure 3.1.16). Interestingly, a p-oxo-dialuminum(III)porphycenate 3.85 analogous to the p-oxo-diiron(III)porphycenates 3.72 and 3.73 has also been prepared. This was accomplished by heating the aluminum(III)porphycenato hydroxide complex 3.76 to 350 °C under reduced pressure (Scheme 3.1.12). 

The similarities between Ga, In and Fe " are manifest in vivo by the binding of all three ions to the serum protein transferrin, Tf, normally used for iron transpQit. The formation constant for the Ga -Tf complex has been found to be and Welch has calculated values for the equilibrium constants for the exchange of trivalent metal ions between EDTA or DTPA and Tf as shown in Table 19. These figures show that only the DTPA complex of Ga is stable with respect to metal exchange with Tf. Table 19 also shows values for the equilibrium exchange reaction between Tf and hydroxide ion. These indicate that, while the indium-Tf complex should be stable to hydrolysis in vivo, in the long term the insoluble Ga(OH)3 should form from the... 

Indium (In, at. mass 114.82) is similar to gallium in its chemical properties. It occurs in aqueous solution exclusively in the III oxidation state. The hydroxide, In(OH)3, precipitates above pH 3-4 but, when freshly precipitated, redissolves in fairly concentrated alkali, thereby displaying weakly amphoteric properties. Yellow 10283 is precipitated at pH 2-3. Indium forms halide, oxalate, tartrate, and EDTA complexes. 

To determine indium in mineral concentrates (containing -0.1% of In), the following procedure has been recommended A weighed sample (0.1-1 g) is decomposed in a mixture of HCl and HNO3, tin is expelled as SnBr4, and Pb is precipitated as PbS04. The hydroxides of metals which, like indium, form sparingly soluble hydroxides, are then twice precipitated with an excess of ammonia. After the precipitated hydroxides have been dissolved in hydrochloric acid, potassium iodide is added, indium is extracted as the iodide complex into diethyl ether, and then stripped into aqueous solution and determined spectrophotometrically with PAR [23],... 

Hamada, S., Kudo, Y, and Kobayashi, T., Precipitation of uniform indium hydroxide particles from indium 2-aminobutyrato complex solutions. Colloids Surf. A, 79, 227, 1993. 

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