Paramagnetic complexes of 9,10-anthraquinone and 9-fluorenone on the metal oxide surface

Paramagnetic complexes of 9,10-anthraquinone and 9-fluorenone adsorbed on the surface of calcium, magnesium, zinc, zirconium, and aluminum oxides and modified Al(2)O(3) as well as on mixed oxides were studied by ESR and electron-nuclear double resonance. Radical anions that do not interact with Lewis acid sites are generated on the surfaces of oxides with electron-donating properties (CaO, MgO). Paramagnetic complexes of the anthraquinone or fluorenone radical anion with Lewis acid sites (coordinatively unsaturated metal cations) are formed in other cases. Several types of similar complexes can be formed. Mechanisms of interaction of the probe molecules with the metal oxide surface were proposed.