Late-transition-metal catalysts for polymerization of olefins have drawn a significant amount of attention owing to their ability to tolerate and incorporate polar comonomers. However, a systematic way to experimentally quantify the electronic properties of the ligands used in these systems has not been developed. Quantified ligand parameters will allow for the rational design of tailored polymerization catalysts, which would target specific polymer properties. We report a series of platinum complexes bearing bisphosphinemonoxide ligands, which resemble those used in the polymerization catalysts of Nozaki and Chen. Their electronic properties are investigated experimentally, and trends are rationalized by using computed spectral properties. Benchmarking computational data with known experimental parameters further enhances the utility of both methods for determining optimal ligands for catalytic application.