Unique Evidence for a RhIII to RhI Reduction by Deoxygenation of a Carbonate Moiety to CO2 by an Out-of-Sphere Phosphane

Abstract

RhIII carbonate generated from either a peroxocarbonate complex [RhCl(CO4)(PR3)3] or [RhCl3(PR3)3] and Na2CO3, is reduced to RhI by deoxygenation of the carbonate moiety to CO2 by an out‐of‐sphere phosphane. The reaction takes place in mild conditions and is implied in the catalytic activity shown by RhI in the oxidation of styrene with O2/CO2 mixtures.

Hydrogenation of a Rhodium Peroxido Complex by Formate Derivatives: Mechanistic Studies and the Catalytic Formation of H2O2 from O2

“…These bands do not show any isotopic shift upon 13 C labeling and can tentatively be associated with vibrations which include the RhO moiety 20b. Based on the 17 O NMR and IR data, we suggest that CO 2 reacts with rhodium peroxido complexes by insertion into a metal–oxygen22 bond rather than by insertion into the OO bond, as was previously suggested 20b,c. A comparable reactivity was found in the reaction of boronic acids with 1 a , in which trans ‐[Rh{κ 2 ‐ O OB(C 6 R 5 ) O }(4‐C 5 F 4 N)(CN t Bu)(PEt 3 ) 2 ] (R=H, F) are formed by cleavage of the RhO bond of the peroxido moiety in 1 a 16a…”

Utilisation of CO2 as a chemical feedstock: opportunities and challenges

“…An early process reported in the patent literature used a complex catalytic mixture. 103a Recent studies have elucidated the reaction mechanism for both homogeneous 104 and heterogeneous 105 catalysts showing two concurrent processes, i.e. (Scheme 12) the "one oxygen" addition to the double bond (that affords the epoxide and its derivatives, i.e.…”

Conditions for the Use of CO2

“…[64][65][66] The reaction has been studied under homogeneous and heterogeneous conditions and the mechanism has been completely elucidated. [67] When a homogeneous catalyst is used the reaction has a short lifetime and low TON as the homogeneous catalysts (Rh-complexes) are converted into different species which are inactive. Under heterogeneous conditions, by using metal oxides [55][56][57][64][65][66][67] as catalysts, the process is characterized by a longer life and is able to reduce the radical oxidation of the olefin affording up to 50% conversion of the olefin into the carbonate.…”