An Efficient and Selective Monohydrido Rhodium(I) Homogeneous Hydrogenation Catalyst Containing a Cyclic Phosphine

Abstract

The preparation of the complex RhH(DBP)4 (where DBP is a drbenzophosphole derivative) is described. It is a very effective and selective catalyst for the homogeneous hydrogenation of terminal olefins. Kinetic and mechanistic data for the hydrogenation of 1-hexene are presented.On dCcrit la prtparation du complexe RhH(DBP)4 dans lequel DBP est un dtrivt dibenzophosphole. Ce complexe est un catalyseur trbs efficace et tres selectif pour hydrogenation homogene des olefines terminales. On presente des donnCes c~netiques et mechanistiques pour I'hydrogCnation de I'hexbne-1.[Traduit par le journal]Can. J. Chem., 52,775 (1974)

Reaction of Dinuclear Rhodium 4,5-Diazafluorenyl-9-Carboxylate Complexes with H2 and CO2

“…The heterolytic cleavage of H 2 is likely across the Rh–O bond, producing complex 2 , which is always observed initially, and what we speculate to be a highly dynamic {Rh(PPh 3 ) 2 H x } n species which is invisible by NMR at 25 °C. Coordinatively unsaturated rhodium monohydride bis-monodentate phosphine complexes of the form “{Rh(PR 3 ) 2 H}” are often proposed as the active species in hydrogenation reactions. − If sufficiently bulky phosphines are used, the coordinatively unsaturated Rh species, or N 2 adducts, can be isolated or observed. , NMR studies at −80 °C were carried out next in the absence and presence of added triphenylphosphine in an attempt to observe or trap any coordinatively unsaturated species.…”

Phosphole-based ligands in catalysis

“…In early studies, hydrido-rhodium complex [RhH( Ph-DBP ) 4 ] was found to be superior to [RhH(PPh 3 ) 4 ] in the hydrogenation of 1-hexene 1b (Scheme 8). 62 On the other hand, [RuCl 2 ( Ph-DBP ) 4 ] showed its ability to catalyze the hydrogenation of allylbenzene 14b into 33 , rather than the isomerisation into methylstyrene 6b , with higher efficiency and selectivity than [RuCl 2 (PPh 3 ) 4 ] (Scheme 25). 63 Note that [RuCl 2 ( Ph-DBP ) 3 ] is also an efficient catalyst for this hydrogenation reaction.…”

Reactions of Sodium Tetrahydroborate and Cyanotrihydroborate with Rhodium(I), (II), and (III) Systems in the Presence of Tertiary Phosphines

“…NaBH,CN in the Presence of DBP Addition of DBP in a 3: 1 ratio to [RhCI-(CO),], (18) in ethanolic solution followed by an excess of NaBH, produces the hydrido complex RhH(CO)(DBP), , which cannot be made by the general method of adding NaBH, to RhCl(CO),(DBP) in the presence of an excess of DBP in boiling ethanol (9). The n.m.r.…”