Nitrogen-based ligands can be classified into several types, including:
1. Amines: Simple compounds like [ethylamine]() and more complex structures like diethylenetriamine. 2. Imines: Formed by the condensation of aldehydes or ketones with amines, such as [Schiff bases](). 3. Pyridines: Aromatic nitrogen-containing ligands like pyridine and its derivatives. 4. Azoles: Five-membered nitrogen-containing heterocycles like [imidazole]() and triazole.
