L. Perrin et al., Computed ligand electronic parameters, from quantum chemistry and their relation to Tolman parameters, Lever parameters, and Hammett constants, INORG CHEM, 40(23), 2001, pp. 5806-5811
The calculated (DFT, B3PW91) A(1) v(CO) frequency in LNi(CO)(3) defines an
electronic parameter that reliably predicts the relative donor powers of a
wide variety of cationic, neutral, and negatively charged ligands. These ca
lculated parameters correlate Very well with the available Tolman and Lever
parameters, and also with Hammett's sigma (m), where available. The method
avoids any experimental limitations and, in particular, can be used for pr
oposed ligands not yet experimentally available.