To investigate the origin of rate enhancement and sequence selectivity, we turned to density functional theory (DFT, Figure ) at a meta-hybrid DFT level. This involved conformational searches and structure optimizations at the TPSSH/def-TZVP level (using the solvation model COSMO and assuming a dielectric constant of infinity), followed by M06-2X/def2-TZVPD single-point calculations. For the final Gibbs free energies, the solvation model COSMO-RS was employed assuming a solvent mixture of 5:1 PO and PTA at 30 °C. Statistical thermodynamic contributions to Gibbs free energies were also taken into account. The most favored structures were identified by assessing a multitude of species as exhaustively as possible, while also considering dimerization equilibria at catalyst concentrations during ROTERP. The reader is referred to the supporting information (ESI Section S6) for a summary of these species and their associated Gibbs free energies.