Pyridine: A Useful Ligand in Transition Metal Complexes

Pyridine (C 5 H 5 N) is being the simplest six-membered heterocycles, closely resembles its structure to benzene. The “N” in benzene ring has its high electronegativity influence on resonance environment and produces markedly different chemistry from its carbon ana - log. The presence of nitrogen and its lone pair in an aromatic environment makes pyri dine a unique substance in chemistry. The sp 2 lone pair orbital of “N,” directed outward the ring skeleton, is well directed to have overlap with vacant metal orbital in producing an σ bonding interaction. This causes pyridine to be a ligand and has been utilized with all transition metals in producing the array of metal complexes. A rich literature of metal complexes is now available with pyridine and its derivatives. Innumerable complexes have been synthesized with academic as well as industrial importance. To shed a light on ligating capability of pyridine, transition metal complexes with pyridine, and its deriva tive is presented in this chapter.