Magnetic clusters and conducting molecular materials from polyoxometalates

The relevance of polyoxometalate chemistry in molecular magnetism and molecular materials is discussed. In the first part we show that these molecular metal-oxides provide remarkable examples of magnetic clusters fur which the nuclearity and the topology can be varied in a controlled manner. They provide ideal models for the study of magnetic interactions in clusters, and for the study of the interplay between electron delocalization and magnetic interactions. In the second part we illustrate the use of polyoxoanions as inorganic components of new hybrid molecular materials having conducting and/or magnetic properties. Two kinds of materials are presented namely, crystalline hybrid salts in which the electron donors are organic molecules of the TTF type or organometallic complexes as the decamethylferrocene, and films formed by polyoxometalates embedded in conducting polymers (of the polypyrrole type). (C) Academie des Sciences/Elsevier, Paris.