Parr's index to describe both electrophilicity and nucleophilicity

We have disclosed a new aspect of Parr's omega value (omega = mu(2)/2 eta), which was originally proposed as an electrophilicity index, and reformed the omega value as a useful single scale from electrophilicity to nucleophilicity by introducing the corresponding epsilon values (epsilon = mu eta). The plot of the to values against the 8 values (omega-epsilon correlation) presented a fine parabola for 65 chemical species: the order of the electrophilicity is seen at negative epsilon values and the order of nucleophilicity is seen at positive a values. (C) 2012 Elsevier Ltd. All rights reserved.