Phosphines represent a ubiquitous and extremely important class of ligands in organometallic chemistry, and their σ-donor properties greatly affect the coordination, thermodynamic stability, and reactivity of transition metal complexes. Phosphines have been shown to significantly modulate the reactivity of many organometallic catalyzed reactions, such as hydroformylation, cross-coupling, and hydrogenation. To develop new organometallic catalytic reactions where stability and reactivity is modulated by phosphines it would be desirable to have extremely fast methods to calculate and explore phosphine properties. In this general effort, Gensch, Sigman, and Aspuru-Guzik recently reported the Kraken database that consists of over 300,000 mostly hypothetical phosphine ligands created based on a combination of experimentally known phosphines. Along with structures, Kraken contains several calculated steric and electronic descriptors. Fey has demonstrated and popularized the utility of ligand descriptors and properties to evaluate possible catalytic activity. One major chemical descriptor that has been used for several decades to compare the σ-donor capacity of phosphines is the Tolman electronic parameter (TEP). The TEP is a very sensitive measure of a ligand's electron donating or electron withdrawing capacity with only minor influence from steric and dispersion type effects. Typically, a Tolman electronic parameter is measured by the A1 symmetric carbonyl stretching frequency for an L-Ni 0 (CO)3 complex, where L is the ligand of interest. Figure displays a 3-dimensional representation of (CH3)3P-Ni 0 (CO)3 with a depiction of the A1 symmetric carbonyl stretch. If the L-type ligand is electron donating to the Ni metal center then there will be a propagated effect for donation to the CO ligands through π-backbonding, which results in weakening the CO bond strength and decreasing the TEP value. Conversely, if the L-type ligand is electron withdrawing to the Ni metal center then there will be less donation to the CO ligands through π-backbonding resulting in a larger TEP value.