Control experiments and spectroscopy studies were carried out to investigate the reaction mechanism. The addition of BHT (butylated hydroxytoluene) to the reaction mixture lowers the yield of the dehydrogenated product 26b indicating the formation of radical intermediates in the reaction (Scheme 2a). When Ni (NO3)2(dtbbpy) and NiCl2(dtbbpy) were used instead of NiBr2(dtbbpy) as catalyst the yield of the desired product 26b dropped to 0% and 12%, respectively (Scheme 2b, c), proving the crucial role of bromide ions in the reaction system.