Advances in molecular uranium chemistry

The synthesis of molecular compounds of uranium which have an unusual oxidation state or configuration, or exhibit specific reactivity or physico-chemical properties, was possible by using ligands which were so far neglected in f elements chemistry and the design of new reactions. The number and variety of precursors were extended, allowing the preparation of metallo-organic derivatives, with the cationic amide and thiolate compounds being of special interest. The development of organo-uranium chemistry involved an enlargement of the classical families, in particular with the introduction of the thiolate and hydride ligands, and the creation of novel classes of compounds, where the linear and bent 'sandwich', 'semi-sandwich', 'mixed sandwich' and 'inverse sandwich' compounds occupy a prominent position. Some of the generally accepted ideas on the chemistry of uranyl complexes have been modified. The molecular magnetism of hetero-polynuclear compounds containing an actinide ion was first explored with Schiff base complexes of the Cu2U type. The factors favouring the differentiation of trivalent lanthanide and actinide ions were brought to light. The potential of uranium compounds in organic synthesis and catalysis was confirmed. (author)