Metal-ammines formation stability

Bjerrum, J. Metal Ammine Formation in Aqueous Solution (Haase, Copenhagen, 1941). Rossotti, F. J. C. and Rossotti, H. The Determination of Stability Constants (McGraw-Hm, New York, 1961)... 

Formation of Metal-ammines.—The compounds may be formed in several ways, such as treating the dry metal salts with ammonia gas until absorption is complete by treating the salts with liquid ammonia or from an aqueous solution of the salt and aqueous ammonia. The method of formation depends on the stability of the amminc. In some eases the aminine has not been isolated in the solid state, and its presence in solution is only indicated by the behaviour of the liquid. 

Williams 22) was the first to point out that decrease in enthalpy usually accounts for a considerable part of the stability increase associated with metal chelate formation. The thermodynamic data in Table III illustrate this effect for a series of ethylenediamine chelates relative to the corresponding metal ammines. The data show that in nearly all cases the increased stability of the metal diamine chelate over that of the amine is due largely to a more favorable heat of formation. This effect is considered due, at least in part, to a more positive heat of formation of the ligand... 

Section 19.5 deals with the development of novel metal ammine systems and focuses on the design of superior metal ammines by closely integrating experimental and calculational work. From a detailed understanding of structure and stability, porosity and particle size, desorption and diffusion, and alloy formation, it is possible to engineer these materials on the nano-, micro-, and macro-scales. 

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