- The development of structure-reactivity relationships has been a long-standing goal of surface science studies. Ironically, though they have been considered much less often than metals, metal oxides appear to offer some of the best opportunities for developing such relationships. The localized electronic structure of oxides permits connections to be drawn from reactivity to the discrete coordination environments and oxidation states of surface cations, and thence to coordination chemistry of metal complexes in solution. Reactions of carboxylic acids on different oxide single crystal surfaces illustrate the roles of surface coordinative unsaturation, oxidation state, and redox properties in determining the surface reactivity of metal oxides. 1993, American Vacuum Society. All rights reserved.