Aromatic hydrocarbons as ligands. Recent advances in the synthesis, the reactivity and the applications of bis(eta(6)-arene) complexes

Synthetic procedures for bis(eta(6)-arene) metal derivatives and aspects of their reactivity are reviewed. Attention is focused on early transition metals (Groups 4-6) but, when necessary, reference will be made to arene derivatives of Groups 7-10, lanthanides and actinides. After a short historical presentation of bis(eta(6)-arene) derivatives, aimed at illustrating the relevance of this class of compounds to the origin and the evolution of organometallic chemistry, the synthetic procedures to bis(eta(6)-arenes) will be discussed in the light of the most recent results. As far as the reactivity of bis(eta(6)-arene) compounds is concerned, particular attention is given to the electron transfer reactions occurring with or without arene displacement; data are reported for the use of low-valent bis(eta(6)-arene) compounds as a useful entry into the inorganic and coordination chemistry of the corresponding metal in non aqueous systems. The use of bis(eta(6)-arene) derivatives of transition metals in low oxidation states (0, +1) as precursors to catalytic systems for the oligomerisation and polymerization of unsaturated monomers and as starting compounds for the preparation of molecule-based magnets, ordered crystals and new materials and Supports is described. (C) 2009 Elsevier B.V. All rights reserved.