Examination of Drago's E(B) and C-B parameters for phosphines through the quantitative analysis of ligand effects (QALE)

Comparison of pairs of physiochemical properties of phosphines and their complexes demonstrates that, in general, at least four independent stereoelectronic parameters are in general required to describe the variations in these properties. Consequently, any two-parameter model such as Drago's E/C model will have limited use in correlation analyses involving phosphines. The QALE analysis of E(B) and C-B shows that these parameters are linear combinations of the QALE parameters chi and theta, with a small contribution from E(ar). Thus, successful application of the E/C model will be restricted to the situation where the property being analyzed depends primarily on chi and theta.