Tetrapodal pentadentate ligands: Single site reactivity and bond activation in iron(II) complexes

Abstract

Tetrapodal pentadentate ligands occupy five coordination positions in a coordination octahedron, thereby providing the metal ion with a square-pyramidal “coordination cap”: In such complexes, all reactivity is focused on a single coordination site. The review highlights recent advances in the coordination chemistry of iron. With a variety of NN₄ ligands, the concept is being used to model non-heme active sites in biomolecules. Tetraphosphane ligands (donor set: NP₄) undergo, depending on the solvent, remarkably specific P–C bond activation reactions, which may be reversed under suitable conditions.