Polydentaatsetel

Polydentaatsetel is a term used in inorganic and organometallic chemistry to describe a class of chelating ligands that can coordinate to a central metal atom or ion through multiple donor atoms situated at different positions on the ligand framework. The word derives from the Latin roots polys (“many”) and dentatus (“toothed”), indicating that the ligand possesses several “tooth‑like” binding sites that allow it to wrap around the metal center. In a polydentaatsetel, the donor atoms may be of various types – nitrogen, oxygen, sulfur, or phosphorous – and can be arranged in either a rigid or flexible manner, thereby influencing the geometry and electronic properties of the resulting complex.

In practice, polydentaatsetel ligands form a wide range of coordination compounds, from simple octahedral chelates such as bis(ethylenediamine)cobalt(III) [1] to more elaborate macrocyclic complexes such as tetraphenylporphyrin binding to iron in heme [2]. The multidentate nature of these ligands imparts stability (the chelate effect) and can enforce specific stereochemical arrangements. Polydentaatsetel complexes are exploited in catalysis, for example in homogeneous hydrogenation reactions where bidentate diphosphine ligands provide both electronic tuning and conformational control [3]. They also find application in materials science for the synthesis of metal–organic frameworks (MOFs) and in biomedical fields where metal ions coordinated by polydentate ligands are used as diagnostic probes or drug delivery vehicles [4].

The field of polydentaatsetel research continues to expand as chemists design new ligands with tailored denticity and bite angles to achieve desired reactivities. Typical challenges involve controlling ligand flexibility, steric congestion, and competing monodentate coordination pathways. Future developments are anticipated to involve hybrid ligands that combine traditional chelating cores with responsive functional groups, enabling switchable coordination chemistry in adaptive molecular systems.