Selective, homogeneous hydrogenation of cycloheptatriene to cycloheptene catalyzed by (η4-cycloocta-1,5-diene)(η6-cyclohepta-1,3,5-triene)ruthenium(0)

Homogeneous Hydrogenation of Alkynes and Dienes

“…Under the reaction conditions (7 bar H 2 , 218C) an average TOF of 16 000 (calculated from TON of 1600) can be reached, though hydrogen diffusion limitations prevent higher rates. The reaction rate is given by the equation: 65 . Thus, the reaction is first-order in palladium and dihydrogen, confirming that mononuclear species are involved in the catalysis.…”

“…Ruthenium(0) complexes containing cyclic polyenes such as Ru(cod)(g 6 -triene) (50) (cod = 1,5-cyclooctadiene; triene = 1,3,5-cyclooctatriene or 1,3,5-cycloheptatriene) have proven to be selective hydrogenation catalysts for the reduction of cycloheptatriene and cyclooctadiene to the corresponding cyclic monoenes [64,65]. The [Ru(cod)] fragment is maintained as the catalytic unit throughout the hydrogenation reaction and the g 6 -coordinated triene (e.g., cyclooctatriene) is hydrogenated to the monoene during the induction period.…”

“…Finally, other rhodium catalysts for the selective diene hydrogenation worth mentioning include [RhCl(PPh 3 ) 3 ] (64), [RhCl(nbd)] 2 (65), and the catalytic sys- [25,77]. Generally, these complexes show chemoselectivity that is similar to or lower than that of the cationic rhodium complexes [Rh(nbd)L n ] + A - (54), with comparable reaction rates.…”

Ruthenium and Osmium

“…The compounds [RuCl 2 (C 6 H 6 )] 2 [36] [38,39] are also very useful starting materials that are commercially available. The complex RuCl 2 (dmso) 4 [40] in Figure 3.4 c has relatively labile ligands.…”

“…3.6). The complex Ru(COD)(COT) is also a useful catalyst for the hydrogenation of trienes to monoenes (see Table 3.1, entry 4) [39].…”