Solutions inorganic complexes

Heteropolyacids (HPA) are the unique class of inorganic complexes. They are widely used in different areas of science in biochemistry for the precipitation of albumens and alkaloids, in medicine as anticarcinogenic agents, in industry as catalysts. HPA are well known analytical reagents for determination of phosphoms, silica and arsenic, nitrogen-containing organic compounds, oxidants and reductants in solution etc. 

In addition to chemical reactions, the isokinetic relationship can be applied to various physical processes accompanied by enthalpy change. Correlations of this kind were found between enthalpies and entropies of solution (20, 83-92), vaporization (86, 91), sublimation (93, 94), desorption (95), and diffusion (96, 97) and between the two parameters characterizing the temperature dependence of thermochromic transitions (98). A kind of isokinetic relationship was claimed even for enthalpy and entropy of pure substances when relative values referred to those at 298° K are used (99). Enthalpies and entropies of intermolecular interaction were correlated for solutions, pure liquids, and crystals (6). Quite generally, for any temperature-dependent physical quantity, the activation parameters can be computed in a formal way, and correlations between them have been observed for dielectric absorption (100) and resistance of semiconductors (101-105) or fluidity (40, 106). On the other hand, the isokinetic relationship seems to hold in reactions of widely different kinds, starting from elementary processes in the gas phase (107) and including recombination reactions in the solid phase (108), polymerization reactions (109), and inorganic complex formation (110-112), up to such biochemical reactions as denaturation of proteins (113) and even such biological processes as hemolysis of erythrocytes (114). 

The aim in solution studies on metalloprotein is to be able to say more about intermolecular electron transfer processes, first of all by studying outer-sphere reactions with simple inorganic complexes as redox partners. With the information (and experience) gained it is then possible to turn to protein-protein reactions, where each reactant has its own complexities... 

Table 8.5 Effective ion diameters (A) for various ions and inorganic complexes in aqueous solution (after Kielland, 1937).

Enrique Moles, 1883-1953. Distinguished Spanish chemist and pharmacist. Professor of Inorganic and Physical Chemistry in the Faculty of Chemical Sciences at Madrid. His papers on non-aqueous solutions, molecular volumes and additivity, inorganic complexes, and atomifc weight determinations were published in the leading journals of Spain, England, France, Italy, and the Netherlands. See... 

J. R. Schoonover and G. P. Strouse, Time-Resolved Vibrational Spectroscopy of Electronically Excited Inorganic Complexes in Solution, Chem. Rev. 1998, 98, 1335. 

Inorganic Complexes in High-temperature Aqueous Solutions 854... 

Na2HP0 solution (NAP) (140 mg/L), to provide a solution containing an inorganic complexing agent to form anionic species with reduced technetium (9). This anion was used instead of carbonate, as the purification system of the anaerobic chamber removes CO from the atmosphere, and a bicarbonate-carbonate solution would not be stable. 

Figure 7.4 Effect of pH cycling on the dissolution of manganese from crustal aerosols under conditions likely both in the atmosphere and on mixing into seawater (Spokes and Jickells, 1996). Manganese shows high solubility at a typical cloud water pH of 2. Solubility decreases slightly at rainwater pH of 5.5 and rapidly at pH 8. Extensive solution phase removal is not seen at pH 8 under conditions designed to mimic seawater, perhaps due to the formation of soluble MnCI+ and MnSOl-. Low pH cycling and inorganic complexation under seawater conditions increase manganese solubility six times over that seen at pH 8 alone.

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