ligands

[EMurphy_2L]

is an atom with two lone pairs polydentate? or no because is cannot form a ring?

[Lara Kristine Bacasen 1L]

Polydentate Ligands are ligands that can attach at several bonding site (book definition). It has more than one donor atom. So that means they most likely have multiple lone pairs to bind to central atom. So yes if it has two lone pairs it is polydentate. The ring is formed with the ligands and the metal.

[Jainam Shah 4I]

Yes, if a ligand has two lone pairs that means there are two potential binding sites for the central atom to attach too. That is the transition metal can bind to that ligand at two places hence with two bonds. The ring structure has more to do with a chelate complex.