While the theoretical model clearly highlighted the beneficial effect of a second Rh(II) center in close proximity to the active site, the computed reaction pathway was not yet consistent with a transformation that could take place at room temperature. Notably, however, the theoretical model does not account for the presence of Rh(III)-O-OH within the MOF pore. While the beneficial effect of the presence of these polar groups could be clearly established experimentally, their absolute concentration or spatial distribution is not known, which precluded inclusion in the theoretical model. Importantly, however, a number of experimentally testable hypotheses result from the lowest energy pathway provided by theoretical calculations: i) the involvement of ethylene in the highest energy transition state suggests that thermal hydrosilylation is associated with an ethylene order of at least 1, likely even 2 (if ethylene serves as the trans ligand on Rh(II) as depicted in Figure ), ii) a polar solvent environment would be expected to stabilize the partial charges created in the transition state of the thermal hydrosilylation reaction, and iii) the amount of dehydrosilylated side product obtained would be expected to be higher for the thermal pathway due to the possibility of facile proton loss from the zwitterionic transition structure. We had shown in our earlier work that thermal conditions led to a hydrosilylation selectivity of 92% whereas light-mediated conditions were associated with a selectivity of 99%. The light-mediated pathway, which proceeds via free silyl radicals, is substantially faster at room temperature than the thermal pathway, which proceeds by direct silyl transfer via a zwitterionic transition. The selectivity of a light-mediated reaction at room temperature is thus expected to be dominated by the selectivity associated with the silyl radical reaction pathway. When the photochemical reaction is carried out at 50 °C, the contribution of the thermal pathway becomes substantial and the selectivity for the formation of the hydrosilylated product drops to 93%. The formation of an increased amount of hydrosilylated product whenever the thermal reaction pathway is a dominant contributor to the reaction rate is consistent with the zwitterionic transition state depicted in Figure . We also investigated the origin of the substantially lower selectivity observed in light-mediated hydrosilylation with the molecular analogue of Rh(III)-3, the results of which are discussed in the Supporting Information (Figure ).