1. Laboratoire SESNAB, UMR MD-1, Faculté des Sciences et Techniques de St Jérôme, Université Paul Cézanne, Aix-Marseille, Avenue Escadrille Normandie Niémen, 13397 Marseille Cedex 20, FranceThis is a Chemical Reviews Perennial Review. The root paper of this title was published in Chem. Rev. 2005, 105, 857, and an Addition and Correction was published in Chem. Rev. 2005, 105, 4233. Updates appear in red.