Electric conductivity of nanocluster polyoxomolybdates in the solid state and solutions

The electric conductivity of nanocluster polyoxomolybdates (POMs) Mo₁₃₂ and Mo₇₂Fe₃₀ with a keplerate structure in aqueous solutions, of these POMs in the solid state, and of Mo₁₃₈ with a toroidal structure was studied. Data on the concentration dependence of the equivalent electric conductivity in solutions and on the specific conductivity of the solid samples were obtained. Solid Mo₁₃₂ showed predominantly electron type of conductivity at nearly room temperatures due to the presence of molybdenum at different oxidation levels; Mo₇₂Fe₃₀, which has metal components at the highest oxidation levels, was found to be poor electric conductor; Mo₁₃₈, which has a lower content of low-valence molybdenum than Mo₁₃₂, showed intermediate conductivity and a reversible transition between the proton and electron types of conductivity.