Photocatalysis of RhCl(PCy3)2 for Cyclohexane Dehydrogenation: Thermal Dissociation of C - H Bond and Photoelimination of H2

Article abstract of DOI:10.1246/bcsj.67.1254

Catalytic cyclohexane dehydrogenation, yielding cyclohexane and dihydrogen, proceeded under photoirradiation on either a three-coordinated complex, RhCl(PCy3)2 (Cy = cyclohexyl), or a dihydride complex, RhClH2(PCy3)2, with almost the same turnover frequencies (8.4 or 8.6, respectively) attained by use of a cut-filter (UV-27) under refluxing conditions (354 K).RhCl(PCy3)2 in cyclohexane gave stoichiometric amounts of cyclohexene and RhClH2(PCy3)2 at 354 K; the latter complex yielded little H2 even at 373 K in toluene.A photocatalysis cycle for cyclohexane dehydrogenation with RhCl(PCy3)2 is proposed, where cyclohexene is yielded by thermal C - H bond dissociation and dihydrogen is photoeliminated from RhClH2(PCy3)2, regenerating the original complex.