DIHYDROGEN COMPLEXES IN CATALYSIS - ISOTOPE EXCHANGE-REACTIONS

Dihydrogen complexes [CpRu(CO)(PR3)(eta-2-H-2)]X (R = Ph (1), Cy (2); X = BF4-, CF3SO3-), [Ru(dppe)H-2(eta-2-H-2)]BF4 (3), and [Ir(bq)(PPh3)H-2(eta-2-H-2)]SbF6 (5) were tested as catalysts for H/D exchange between ROH and D2. Complex 5 is the most efficient, while 3 is moderately active and 1 and 2 are essentially inactive. Maximum activity arises when an M-H group is cis to a coordination site capable of binding both H-2 and ROH. The relevance of these results to the mechanism of H/D exchange in hydrogenase is also discussed.