Metal Surface Base Function. Adsorption of Boron Trifluoride and Boron Trichloride


In a continuing effort to characterize metal surfaces by their interaction with different classes of molecules, the base function of metal surfaces is examined via adsorption of BF3 and BCl3. Using infrared spectroscopy, the following information has been obtained about the adsorption of the pure Lewis acids BF3 and BCl3. BF3 chemisorbs without dissociation on vanadium, iron, nickel, copper, and palladium films. No chemisorption on aluminum films is detected. The BF3–metal surface complexes are quite stable with respect to air. CO replaces adsorbed BF3 on nickel and palladium. It replaces BF3 on iron to a much smaller extent. BF3 chemisorbed on vanadium and copper is not replaced by CO. Chemisorbed BF3 is electron withdrawing compared to chemisorbed CO. BCl3 adsorbs on Fe and Ni without dissociation. Basicity of the metal surface is demonstrated to be a useful concept by showing that the displacement of BF3 by CO correlates with the expected basicity of the surface as measured by valence-state ionization potentials. © 1972, American Chemical Society. All rights reserved.

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Journal of the American Chemical Society