Polydentate and Chelating Ligands

[Jason Nguyen_1B]

Hi! I understand that ligands can be polydentate if they are able to form two or more bonds to the transition metal cation and thus be a chelating ligand. However, for a ligand to be polydentate and chelating, does the ligand have to follow the lonepair-spacer-spacer-lonepair model? If so, are there any exceptions?

[Faaizah Arshad 1H]

Yes the ligand must follow the lone pair spacer spacer lone pair model in order to be a chelating ligand because that is the only formation that allows the ligand to "wrap around" a transitional metal cation

[shevanti_kumar_1E]

Professor Lavelle mentioned in lecture that a chelate is defined as a complex containing a ligand that forms a ring of atoms that includes the central metal atom. In order for that to happen the lone pair- spacer-lone pair condition needs to be met.