Ruthenium dihydrogen complex for C-H activation:: Catalytic H/D exchange under mild conditions

Calalytic H/D-exchange reactions were Studied with [Ru(dtbpmp)(eta(2)-H-2)(H)(2)] (1) as catalyst. Under mild reaction conditions (25-75 degrees C) a wide range of arenes and olefins undergo H/D exchange with [D-6]benzene. A preference for protons at sp(2) carbons was observed with conversions Lip to >90% and significant regioselectivity in certain cases, For more reaction insights NMR-based kinetic studies were performed with naphthalene as substrate, revealing an activation energy of 15.8 kcal mol(-1) for the H/D exchange at the beta-position. Furthermore, the key steps of the reaction mechanism were investigated by means of DFT calculations for both model complexes (PMe2 donor sites) and real catalysts (PtBu2 donor sites). The calculations resulted in Gibb's free activation energies in the range of 10-16 kcal mol(-1), indicating H/D exchange at the beta-position of naphthalene to he clearly favoured over the alpha-position, Much is in full accordance with the experimental observations. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).