Tripodal tetraamine ligands containing three pyridine units:: The other polypyridyl ligands

The chemistry of tripodal ligands containing three (2-pyridyl)-alkyl arms attached to an aliphatic N atom (tripyridyl tripodal ligands) is reviewed. An outline of the variety of such ligands is given and methods for their synthesis are detailed. The structures of metal complexes containing tripyridyl tripodal ligands are briefly discussed, with particular emphasis on the structures adopted by complexes containing metal ions of varying coordination number. A brief overview of the complexes of tpa, the most widely used tripyridyl tripodal ligand, and its derivatives, is given. The electronic properties of tripyridyl tripodal ligands are detailed, as determined from spectroscopic, NMR, magnetochemical, electrochemical and pKa measurements on their metal complexes. Some examples of the reactivity of complexes containing tripyidyl tripodal ligands are given which outline the importance of both steric and electronic effects of the ligands in determining the reactivity of the metal complexes. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008.