Zero‐Valent Amino‐Olefin Cobalt Complexes as Catalysts for Oxygen Atom Transfer Reactions from Nitrous Oxide

Abstract

The synthesis and characterization of several zero-valent cobalt complexes with a bis(olefin)-amino ligand is presented. Some of these complexes proved to be efficient catalysts for the selective oxidation of secondary and allylic phosphanes, as well as diphosphanes, even with a direct P-P bond. With 5 mol % catalyst loadings the oxidations proceed under mild conditions (25-70 °C, 7-22 h, 2 bar N O) and afford good to excellent yields (65-98 %). In this process, the greenhouse gas N O is catalytically converted into benign N and added-value organophosphorus compounds, some of which are difficult to obtain otherwise.

CO Oxidation by N2O Homogeneously Catalyzed by Ruthenium Hydride Pincer Complexes Indicating a New Mechanism

“…9,12 This result encouraged us to explore a catalytic CO oxidation by N 2 O initiated by O-transfer into a M–H bond. 8,9 We propose that a H–M–CO complex may undergo O-transfer from N 2 O into the M–H bond to generate a HO–M–CO species, followed by intramolecular interaction between M–OH and CO ligand to form a M–COOH intermediate (Scheme 1). 10 CO 2 release in the presence of CO regenerates the H–M–CO complex, thus completing the catalytic cycle.…”

Tuning Iridium(I) PCcarbeneP Frameworks for Facile Cooperative N2O Reduction

“…[14--16] Gianetti and co--workers similarly propose "conventional" N 2 O activation in reactions that utilize nitrous oxide as a hydrogen acceptor or oxygen atom transfer agent. [17,18] In contrast, Milstein and co--workers have demonstrated the catalytic hydrogenation and hydrosilation of N 2 O proceeds via a MLC mechanism involving ligand aromatization/dearomatization using a ruthenium PNP complex. [19] In this context, we found that iridium PC carbene P pincer complexes interact with N 2 O via a distinct type of MLC.…”

Nitrous Oxide Promoted Pauson–Khand Cycloadditions

“…Moreover, nitrous oxide is inexpensive and widely available, yet there are few applications of the gas as a reagent in chemical synthesis . Most transition-metal-catalyzed or -mediated processes that currently utilize N 2 O involve direct transfer of the oxygen atom of N 2 O to the transition-metal center . However, we hypothesized that, if N 2 O could oxidize the CO ligand rather than cobalt, we could promote the PKR and avoid the need for large excesses of solid oxide promoters (Scheme B).…”