Gallium stability constants

Ar,A,-bis(2-hydroxybenzyl)-ethylenediamine-A,A, -diacetic acid (HBED) and IV-hydroxybenzyl-ethylenediam i ne- A-, A", N -iri acetic acid (HBET) are multidentate ligands investigated for coordination with gallium and indium (Figure l).78 HBED, with its two phenolate donor groups, led to increased stability constants over HBET. 

Accounts of gallium which include coordination chemistry are those of Greenwood,429 Sheka et a/.,430 and Wade and Banister.1 Early work on the adducts of gallium trihalides with Lewis bases was documented in 1963,4 and this area was thoroughly reviewed by Pidcock in 1972.431 Other aspects of gallium coordination chemistry were examined by Tuck.431 Stability constants have been tabulated for a number of Ga3+ complexes.7,8... 

Aqueous solution stability constants for the aryl substituted complexes have been determined. The ML3 complexes are highly stable at 25 °C the overall stability constant (/Ss) for the parent complex (17) R = H is 10 . At ligand to metal ratios > 1, the hgands prevent gallium hydrolysis even at millimolar concentrations and under slightly basic conditions the effective formation constant for ML3... 

There are other reported stability constants for the formation of GaOH that have not been listed in Table 13.19. These data suggest a stability that is often many orders of magnitude different from the accepted data listed in the table. The data from these studies have not been retained in this review (Fricke and Meyring, 1928 Wilson and Taube, 1952 Alimarin, Abdel Khamid and Puzdrenkova, 1965 Savostin, 1965 Nazarenko, Antonovich and Nevskaya, 1968 Biryuk and Nazarenko, 1973). Where available, data from these studies for the higher monomeric species of gallium(lll) are also not retained. 

Instability constants have been measured for molybdate and tungstate heteropolycomplexes of gallium. These complexes are very stable, with, however, decreasing stability in the series GaM,2>GaM<,>GaM6>GaM3. ... 

There is a paucity of available data for the solubility of indium oxide and hydroxide phases. As the first hydrolysis constant of indium has a stability that lies between those of aluminium and gallium, it is expected that the solid hydroxide phase would also exhibit this behaviour. However, a number of studies (Heyrovsky, 1925 Oka, 1938 Moeller, 1941 Lacroix, 1949) have indicated a solubility that was larger than that seen for aluminium(III). It is believed that this would be unlikely and, as such, these data are not retained. AkseTrud and Spivakovskii (1959) obtained a solubility that was nearly four orders of magnitude smaller than... 

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