On the condensed Fukui function

A critical comparison among recently proposed methods for evaluating the co ndensed Fukui function neglecting relaxation effects is presented. The sign of the condensed Fukui function is discussed and arguments for a positive definite condensed Fukui function are given. Our numerical calculations in two series of molecules show that: (i) the condensed Fukui function can giv e, in general, valuable information about the site selectivity in chemical reactions and systematization in a family of molecules. In particular, it h as been shown that the selectivity towards protonation in anilines and deri vatives molecules can be correctly assessed by the electrophilic Fukui func tion described in this paper. Within this approach non-negative values for the condensed Fukui function are obtained for the relevant protonation site s in these polyfunctional systems; and (ii) the solvent effects on the cond ensed Fukui function are negligible, confirming a recently presented theore tical prediction. (C) 2000 American Institute of Physics. [S0021-9606(00)30 331-2].