Oxidation of phenyl and hydride ligands of bis(pentamethylcyclopentadienyl)hafnium derivatives by nitrous oxide via selective oxygen atom transfer reactions: insights from quantum chemistry calculations

Nitrous oxide activation by picoline-derived Ni-CNP hydrides

Oxygen atom transfer (OAT) from N2O to the Ni-H bond of proton-responsive picoline-derived CNP nickel complexes has been investigated both experimentally and theoretically. These Ni-CNP complexes efficiently catalyse the reduction of N2O with pinacolborane (HBpin) under mild conditions.

Non-innocent PNN ligand is important for CO oxidation by N2O catalyzed by a (PNN)Ru-H pincer complex: insights from DFT calculations

Milstein et al. developed an efficient and mild method for CO oxidation by N₂O to give CO₂ and N₂ catalyzed by a (PNN)Ru-H pincer complex. To gain mechanistic information on this catalytic transformation, the reaction mechanism has been studied using density functional theory (DFT) calculations. It was found that the catalytic cycle for CO oxidation by N₂O proceeds in three stages: N₂O activation to form a (PNN)Ru-OH intermediate, CO insertion into the Ru-OH bond to form a (PNN)Ru-COOH intermediate and CO₂ release from (PNN)Ru-COOH. In the CO₂ release stage, CO₂ is not released via a β-H elimination mechanism as proposed in experiments, instead it is released via a deprotonation mechanism. The calculations demonstrated that the Ru-H bond of the catalyst plays an important role in facilitating the activation of N₂O, which is the rate-determining step for the whole catalytic cycle, and the non-innocent PNN ligand is very important for CO oxidation by N₂O. Our theoretical results are consistent with the experimental observations and could help design highly efficient catalysts for N₂O activation.

A substrate-dependent mechanism for the reactions of a hydrido(hydrosilylene)ruthenium complex with carbonyl compounds: insights from quantum chemical calculations

The reactivity difference between ketones and aldehydes towards the ruthenium silylene hydride complex is dependent on the substituents of the carbonyl substrates.

Dehydrogenation of benzyl alcohol with N2O as the hydrogen acceptor catalyzed by the rhodium(i) carbene complex: insights from quantum chemistry calculations

The detailed mechanisms of the dehydrogenation of benzyl alcohol with N₂O as the hydrogen acceptor catalyzed by the rhodium(i) carbene complex for the formation of the corresponding carboxylic acid or ester have been investigated via density functional theory (DFT) calculations at the M06 level of theory. Three cycles were considered for the formation of benzaldehyde, benzyl benzoate and benzoic acid. On the basis of the calculations, the rate-determining step for these three cycles is involved in N₂O activation by the rhodium ammine hydride complex with an activation barrier of only 22.6 kcal mol^-1, which is different from the previous mechanism proposed by Gianetti and co-workers, where the hydride is transferred from the Rh atom to the oxygen atom of N₂O with a barrier of 30.5 kcal mol^-1. In addition, the calculations also demonstrated that one more N₂O is necessary to give benzoic acid, and the reaction can only take place under anhydrous conditions. Present calculations are in good agreement with the experimental observations and provide new insights into the dehydrogenation of benzyl alcohol with N₂O as the hydrogen acceptor.