ELECTROSORPTION OF HARD AND SOFT AROMATIC DERIVATIVES ON MERCURY

An 'intrinsic' value of the adsorption Gibbs energy (DELTA-G(int)-degrees) parallel-to, not directly proportional to the measured DELTA-G(ads) parallel-to, has been evaluated for a set of 28 aromatic, heterocyclic and naphthalenic derivatives. The structural feature of (DELTA-G(int)-degrees) parallel-to is rationalised in terms of a 'soft' interaction with mercury at the point of zero change, 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, lambda, has been related in a satisfactory way to DELTA-N (the fractional number of electrons transferred) calculated taking into account the absolute electronegativity, chi, and the hardness, eta, both of the adsorbate and of mercury.