Adsorption of nitrobenzene and some simple derivatives on the Cu(110) surface

Abstract The chemistry of nitro- and amine-substituted aromatic molecules on a Cu(110) surface has been studied using Fourier transform infrared spectroscopy, by comparison of the adsorption of nitrobenzene (NB), p -dinitrobenzene ( p DNB) and p -nitroaniline (pNA). When nitrobenzene was adsorbed on a clean Cu(110) surface at room temperature, it decomposed to form a phenyl species with the C 2 axis nearer the surface normal than parallel. At 83 K, multilayer nitrobenzene formed with a vibrational spectrum, in good agreement with gas-phase data; upon warming, a phenyl species remained, which was stable to about 350 K. AES of the species present following dosing at 300 K showed carbon and oxygen but no nitrogen. When p -dinitrobenzene was adsorbed it decomposed, losing one NO 2 , to form a stable nitrophenyl species on Cu(110) orientated with the C 2 axis closer to the surface normal than the phenyl species derived from nitrobenzene. In contrast, p -nitroaniline does not decompose on the Cu(110) surface at room temperature. Multilayer and monolayer p -nitroaniline are distinguished by frequency shifts of NO 2 and NH 2 modes, attributed to intermolecular hydrogen bonding. In the monolayer, the amine group appears to stabilise the ring-nitro group bond, allowing bonding to the surface via the NO 2 group in an orientation perpendicular to the surface.