Adsorption of 2,2′-bipyridyl on magnesium oxide and calcium oxide. Infrared spectra of neutral and anionic surface species

Abstract

Infrared spectra show that 2,2′-bypiridyl interacts with highly dispersed MgO and CaO forming three different types of surface species: physisorbed neutral molecules, chemisorbed neutral molecules and chemisorbed monoanions. The concentration of organic anions is small, but unusually high absorptivity allows intense infrared spectra to be recorded; in contrast to their behaviour in solution, the organic anions are very stable on surfaces. Both the neutral and the charged chemisorbed species are thought to form chelates with the surface cations, the frequencies of the ring modes being dependent on the radii of the adsorbing ions.