Die Kinetik typischer Hydrolysereaktionen von mehrwertigen Kationen

Abstract

This review summarizes kinetic investigations concerning the homogeneous hydrolysis reactions of multivalent metal cations in aqueous solution. - Three main types of reactions are discussed : 

a) Protolysis of aquated cations to form mononuclear metal-hydroxo-complexes. 

b) The formation and fission of binuclear μ-hydroxo-bridged or μ-oxo-bridged metal hydroxo complexes. 

c) The formation and acid degradation reactions of higher polynuclear metal hydroxo complexes. 

Whereas the protolysis reaction of aquo-metal cations is a simple and fundamental (acid-dissociation) reaction the formation of the binuclear complexes resembles in most cases closely the metal-anion-complex formation. The formation and degradation of the higher metal hydroxo complexes, however, mostly proceeds in two or more parallel reaction paths. — Both the successive addition of mononuclear metal-hydroxo-species to metal hydroxo complexes of lower molecular weight as well as the initial formation of discrete sub-complexes which finally combine to the stable complex are observed for the formation reaction.