Four imidazole adsorption geometries and their electronic structures were studied on Ag (111) by EHMO tight-binding calcns. (representing the Ag surface as a monolayer slab). The most favored configuration is standing-up at bridge sites with imidazole bound to Ag via pyridine ring N lone pair electrons. This results in formation of a multi-center s bond between N p and adjacent Ag s orbitals. The electron d. change induced by adsorption indicates that some electrons flow from the Ag into a p antibonding MO of chemisorbed imidazole. The calcns. also indicate that the chemisorbed imidazole tends to undergo facile cleavage of the N-H bond (in agreement with experimental observations).

Key words: SILVER, IMIDAZOLE, ELECTRONIC STRUCTURE, MOLECULAR ORBITAL THEORY, SURFACES ADSORPTION