Chelate and polydentate

[Gabriella Bates 2L]

Can someone explain what a chelating ligand is and why it's important? Also, how is this related to a ligand being polydentate?

[Harry Zhang 1B]

A chelating ligand is a special type of ligand that binds to the central transitional metal at more than one site, forming a ring-like structure. Chelates are especially important in biological systems(Cisplatin can prevent DNA replication; myoglobin carries oxygen...). This relates to a ligand being polydentate because the ligand in a chelate binds("bites down" on the) to the central atom at more than one site.

[Clarice Chui 2C]

Relating to the chelate part of your question, a chelate is a complex containing a ligand that forms a ring of atoms that includes the central metal atom. Chelating ligands bind cations tightly and are significant in nature especially. For example, the book discusses how chelating ligands lie behind the body's the surface to produce a fever if infected by bacteria. Polydentate ligands can occupy more than one binding site simultaneously. Polydentates can form chelates.