Tripodal Triamidometallates of the Heavy Group 14 Elements: Inorganic Cages with Remarkable “Ligand Properties”

Anionic main group metal donors with potentially interesting ligand properties are obtained if ate complexes of the heavy p-block metals are formed by coordination between tripodal amides and divalent group 14 metal centres. The limitations of this approach, due to the potential oxidation by the central transition metal atom, may in part be suppressed by the presence of electronegative substituents at the MII centre, which makes the metallates less reducing. The considerable stability of the triamidostannates(II) towards AgI or AuI−III is testimony to the practical significance of this. The most characteristic structural consequence of the rigid amido cages is the well-defined orientation of the peripheral N-substituents, which gives rise to very large cone angles for the monodentate ligands in their transition metal complex derivatives. These angles considerably exceed those of “ordinary” metallate groups or of the isolobal neutral group 15 ligands, and so would be expected to favour low coordination numbers in transition metal complexes. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)