The experiments show that the bromide ion is oxidized by the excited photocatalyst, and no oxidation of the nickel complex occurs. Light "on-off" experiments suggest that continuous light irradiation is required for the reaction to proceed (Fig. ). The quantum yield of the reaction was determined as 1.4%. Hence, a radical chain process is not expected for this transformation. The evolution of hydrogen gas was confirmed by headspace GC (Fig. ). A two-pot transfer hydrogenation experiment, connecting the reaction headspace of the dehydrogenation reaction to a rhodium-catalyzed hydrogenation reaction of cyclododecene in another vessel (Scheme 2d), confirmed the evolution of 1 molar equivalent of H2.