What Distinguishes the Strength and the Effect of a Lewis Acid: Analysis of the Gutmann–Beckett Method

IUPAC defines Lewis acidity as the thermodynamic tendency for pair formation. This strength property was recently specified global (gLA), and is gauged example by fluoride ion affinity. Experimentally, usually evaluated effect on a bound molecule, such induced 31P NMR shift of triethylphosphine oxide in Gutmann–Beckett (GB) method. type scaling called effective (eLA). Unfortunately, gLA eLA often correlate poorly, but reason this unknown. Hence, acid are two distinct properties, they granted interchangeably. The present work analyzes thermodynamic, specific, London dispersion effects GB numbers 130 acids theory experiment. deformation energy identified prime cause critical deviation between its correction allows unification first time.