We evaluate trends in our Fe and Ru catalysts by studying their activity for polyolefin functionalization via C-H hydroxylation. We assume that C-H activation in polyolefins occurs via the widely-recognized radical rebound mechanism. To balance computational cost and realism in our high-throughput DFT-based studies on transition metal catalysts, we first performed control DFT calculations to identify a suitable model compound for long-chain polymers using a representative catalyst (Supporting Information Figure and Text S1). Here, we investigated the influence of alkane chain length and metal-local steric interactions stemming from hydrocarbon branching on the radical rebound reaction energetics. We find that both long-range interactions arising from carbon atoms that are distant from the metal active site as well as steric interactions from nearby branched substituents have negligible influence on the reaction energetics (Supporting Information Figure and Text S1). Thus, we select propane as our model compound for polyolefins that undergo C-H activation at a secondary carbon, which in this case forms isopropanol. We calculate the reaction energetics for the radical rebound propane-to-isopropanol conversion over mononuclear Fe and Ru complexes in a single oxidation state (i.e., M(II)), excluding higher oxidation M(III) catalysts since they seldom have as favorable radical rebound energetics as M(II) catalysts. In the radical rebound mechanism catalytic cycle, the open metal site in the square pyramidal resting state structure (1) of the catalyst undergoes two-electron oxidation to form a high-valent terminal metal-oxo species (2), which we model using the common oxidant N2O as the oxygen atom source (Figure ). The reaction energy (see Sec. 3) for the metaloxo formation, DE(oxo) is computed as: