Additionally, the ratio of cyclized product A to linear product B should demonstrate no dependence on Ni catalyst loading for an inner-sphere radical rebound mechanism, whereas free radical capture processes are known to show a directly proportional relationship between A:B and catalyst loading. From these experiments, a ratio of A:B = 1.75:1 under the non-stereoretentive conditions was found, a result which strongly contrasted with the ratio of A:B = 0.28:1 under the stereoretentive conditions (Figure ). The clear switch to prefer the linear product under the present conditions supports a fast, unimolecular radical production and rebound mechanism.