A variety of data (spectral, kinetic, and polarographic) is presented for a series of pyridinium iodides in order to establish evidence for the nature of the charge-transfer (CT) interactions of these salts. Two CT bands are normally observed in the absorption spectra of pyridinium iodides. The experimental evidence corroborates assignment of these bands to electronic transitions from the highest occupied molecular orbital of iodide ion to two closely located vacant molecular orbitals in the pyridinium ion. Support was not obtained for an alternate explanation involving formation of iodine atoms in the 2Pi/2 and 2Py2 states upon electronic excitation of the pyridinium iodide. It is further affirmed that the CT contribution to the ground state of the pyridinium iodide ion pair is quite small. The ground-state stabilization of the CT complex is thus primarily electrostatic.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.