Electrosorption of ‘hard’ and ‘soft’ aromatic derivatives on mercury

Abstract

An ‘intrinsic’ value of the adsorption Gibbs energy (ΔG^°_int)^∥, not directly proportional to the measured ΔG^∥_ads, has been evaluated for a set of 28 aromatic, heterocyclic and naphthalenic derivatives. The structural feature of (ΔG^°_int)^∥ is rationalised in terms of a ‘soft’ interaction with mercury at the point of zero charge, on the basis of the parr and Pearson concept, accounting on a quantitative basis for the different adsorbability of the compounds. Moreover, the partial charge-transfer coefficient, λ, has been related in a satisfactory way to ΔN(the fractional number of electrons transferred) calculated taking into account the absolute electronegativitiy, χ, and the hardness, η, both of the adsorbate and of mercury.