Parameters to Predict kp. Matson and coworkers have proposed that the DFT-calculated HOMO energy levels of exo-NB monomers correlate well with their kp values in G3-initiated ROMP. To determine if TCNs and TCNDs follow this trend, the HOMO energies for each monomer shown in Figure were calculated using the M06-2X functional and dev2-TZVP basis set (with a conductor-like polarizable continuum model for chloroform) and plotted against the measured ln(kp) values (Figure ). The HOMO energies ranged from -183 kcal/mol to -194 kcal/mol, which falls within the range reported for other ROMP monomers (-174 kcal/mol to -197 kcal/mol) calculated with the same functional and basis set. In agreement with Matson and coworkers, a positive correlation between kp values and HOMO energies was observed; however, NB-CO2Me stands out as having a much larger kp value than its HOMO energy would predict. Notably, NB-CO2Me is the only monosubstituted norbornene (only one of the two exo positions is substituted) of the monomers studied here.