Autocatalytic reduction of the cis-bis(2,2′-bipyridyl)dichlororhodium(III) ion in alkaline aqueous ethanol under a hydrogen atmosphere

Abstract

The ion cis-[Rh(bipy),CI,]+ (bipy = 2.2'-bipyridyl) is reduced in alkaline aqueous ethanol under hydrogen to the known [Rh(bipy),]+ ion. A detailed kinetic study of this reaction has been carried out and the rate equation governing the reaction is shown to be of the form dThe observed rate constant varies with hydroxide-ion concentration, but is independent of the concentration of added chloride ion. The variation of rate with temperature is also reported. A mechanism is postulated to account for the experimental results.

Homogeneous metal catalysis for conversion between aromatic and saturated compounds

“…Transfer hydrogenation In 2006, Frediani [82] demonstrated pre-activation of cis-[Rh(bipy) 2 Cl 2 ][Cl]•2H 2 O(47) with NaOH to generate an effective catalyst for transfer hydrogenation of quinoline and pyridine (Scheme 51). In accordance with a previous study by Miller[83], Frediani proposed alkaline treatment of 47 initially results in formation of the cationic species [Rh(bipy) 2 ] + (48; Scheme 52). Coordination of i PrOH and subsequent hydride migration then facilitates entry into the catalytic cycle as the monohydride 49.…”

Quinoline transfer hydrogenation by a rhodium bipyridine catalyst

“…These three complexes 4-6 are catalytically active in the hydrogenation of quinoline giving results comparable with those previously reported with other ruthenium systems like RuCl 2 (CO) 2 (PPh 3 ) 2 and Ru 4 H 4 (CO) 12 , but operating under milder conditions and with a lower catalyst/substrate ratio [6,7]. The complex 6 is also catalytically active in the hydrogenation of pyridine and methylpyridine although to a lesser extent than quinoline, confirming a strong influence of the bonding mode of nitrogen containing heterocycles to the metal center on the conversion and selectivity of these reactions 1 [5,6,8,9].…”

Asymmetric Catalysis by Architectural and Functional Molecular Engineering: Practical Chemo- and Stereoselective Hydrogenation of Ketones

“…Noyori and T. Ohkuma activity in the presence of methanolic NaOH (Scheme 4), [33] where the [Rh(bpy) 2 ] species (bpy bipyridine) was proposed as a catalyst. [34] [Rh 2 Cl 2 (OCOH) 2 (bpy) 2 ] [35] and a [RhClP(C 6 H 5 ) 3 (cod)]/NaBH 4 combined system [36] (cod cycloocta-1,5-diene) also effected hydrogenation under basic conditions. Some phosphane ± ruthenium complexes were known to hydrogenate simple ketones, [37,38] but their activities were normally lower than those of the rhodium complexes.…”