Pyridine: A Useful Ligand in Transition Metal Complexes

Abstract

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 analog. The presence of nitrogen and its lone pair in an aromatic environment makes pyridine 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 derivative is presented in this chapter.

Cesium Ion‐Mediated Microporous Carbon for CO2 Capture and Lithium‐Ion Storage

“…This XPS result is particularly remarkable, as pyridine‐like nitrogen is well known to be unstable at high temperature compared with the other two configurations [34,36] . Pyridine‐like nitrogen is characterized as a Lewis base owing to its lone‐pair electrons and readily forms complexes with a metal ion [34,37,38] . On the basis of the XPS results, we thus speculate that the intercalated Cs ions are effectively bound with pyridine‐like nitrogen to form metal‐pyridinic nitrogen complexes, which contributes to the high portion of pyridine‐like nitrogen even after the activation process at high temperature of 700 °C.…”

Functional Microfiber Nonwoven Fabric with Copper Ion-Immobilized Polymer Brush for Detection and Adsorption of Acetone Gas

“…Since 4-AMP also possesses the characteristics of the amine group, it seemed that it would facilitate the immobilization of metal ions. In addition, it was expected to show high introduction capability in the GMA with an epoxy group-grafted MNWF because it has an amino group [ 37 ]. The method of introducing functional groups was determined based on research data on the bonding of metal ions with 4-AMP or 2-picolylamine, similar to 4-AMP’s molecular structure [ 33 , 34 , 38 , 39 ].…”

S2N2– A 6π‐Electron Ligand with Tunable σ‐ and π‐ Donor‐Acceptor Property

“…This interaction contributes only 8.2 % of the total orbital interaction energy. Hence, S 2 N 2 in 1Mo can act as a strong σ‐donor and weak π‐acceptor ligand, which is similar to N‐heterocyclic aromatics like pyridines . Furthermore, it can also act as σ‐acceptor at the S‐atom by the charge transfer of N lone pair to S 2 N 2 σ*‐MO.…”

“…N‐donor aromatic hydrocarbons, such as pyridine and its structural analogs represent a class of extremely valued ligands and ubiquitously have played important roles in the development of coordination chemistry . Interestingly, the heteroatom substitution in the aromatic hydrocarbons introduces Lewis basicity due to σ‐lone pair of nitrogen and Lewis acidity due to C−N π*‐orbitals . Moreover, the interactions of these classes of compounds with the transition metal fragments could be widely varied from the formation of σ‐type or π‐type complexes.…”