Structures, properties and applications of heteropoly compounds

The present paper tries to give a survey of the field of heteropolyanion compounds the first of which were described as early as 1826 by Berzelius and of heteropolycation compounds which were prepared only recently. There is an obvious similarity between these two classes of compounds although the heteropolyanions are formed of transition metals of subgroups 6 and 5 (Mo, W, V, Nb, Ta) while in the heteropolycations the main group metal aluminium functions as the polyatom. The introductory chapter presents a short historical survey; the following chapters describe synthetic methods, structural interrelationships and applications of these two classes of compounds. The coordination number of the heteroatom with respect to oxygen was chosen as the principle of classification of the heteropolyanions. This allows to show the close structural relations existing between anionic and cationic complexes. (author)