O-Abstraction Reactions of Nitrous Oxide with Cp2Ti(II) and Other Middle Transition Metal Complexes

Mechanistic Insights into Activation of Carbon Monoxide, Carbon Dioxide, and Nitrous Oxide by Acyclic Silylene

Owing to an empty p orbital and a lone pair of electrons on the Si center, silylene exhibits reactivity similar to a transition-metal system capable of activating H₂/C-H bonds and small molecules. In this work, with the aid of density functional theory calculations, we systematically investigated the reactions of an acyclic silylene with CO, CO₂, and N₂O. The detailed mechanisms obtained lead to an in-depth understanding of the silylene single-site ambiphilic reactivity.

Rhodium(I) Pincer Complexes of Nitrous Oxide

The synthesis of two well-defined rhodium(I) complexes of nitrous oxide (N2 O) is reported. These normally elusive adducts are stable in the solid state and persist in solution at ambient temperature, enabling comprehensive structural interrogation by 15 N NMR and IR spectroscopy, and single-crystal X-ray diffraction. These methods evidence coordination of N2 O through the terminal nitrogen atom in a linear fashion and are supplemented by a computational energy decomposition analysis, which provides further insights into the nature of the Rh-N2 O interaction.

A Multifunctional Pincer Ligand for Cobalt-Promoted Oxidation by N2 O

The divalent cobalt complex of the diprotic pincer ligand bis-pyrazolylpyridine, (H₂ L)CoCl₂ , is dehydrohalogenated twice by LiN(SiMe₃ )₂ in the presence of PEt₃ to give monomeric S=1/2 LCo(PEt₃ )₂ (1), fully characterized in the solid-state and solution as a square pyramidal monomer with a long axial Co-P bond. This 17-electron species reacts in time of mixing with N₂ O to form L₂ Co₂ (μ-OPEt₃ ) (2)+3 OPEt₃ , the former the first example of phosphine oxide bridging two transition metals. The same products are formed from O₂ , and divalent cobalt persists even in the presence of excess oxidant. Species (2) catalyzes oxygen atom transfer (OAT) for generation of O=PEt₃ from PEt₃ from either N₂ O or O₂ . Bridging and terminal cobalt oxo intermediates are suggested, and the electron donor power, and potential redox activity of the dianionic pincer ligand is emphasized.

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

The mechanisms for the oxidation of phenyl and hydride ligands of bis(pentamethylcyclopentadienyl)hafnium derivatives (Cp* = η(5)-C5Me5) by nitrous oxide via selective oxygen atom transfer reactions have been systematically studied by means of density functional theory (DFT) calculations. On the basis of the calculations, we investigated the original mechanism proposed by Hillhouse and co-workers for the activation of N2O. The calculations showed that the complex with an initial O-coordination of N2O to the coordinatively unsaturated Hf center is not a local minimum. Then we proposed a new reaction mechanism to investigate how N2O is activated and why N2O selectively oxidize phenyl and hydride ligands of . Frontier molecular orbital theory analysis indicates that N2O is activated by nucleophilic attack by the phenyl or hydride ligand. Present calculations provide new insights into the activation of N2O involving the direct oxygen atom transfer from nitrous oxide to metal-ligand bonds instead of the generally observed oxygen abstraction reaction to generate metal-oxo species.

Binding and activation of N2O at transition-metal centers: recent mechanistic insights

No laughing matter, nitrous oxide's role in stratospheric ozone depletion and as a greenhouse gas has stimulated great interest in developing and understanding its decomposition, particularly through the use of transition-metal promoters. Recent advances in our understanding of the reaction pathways for N(2)O reduction by metal ions in the gas phase and in heterogeneous, homogeneous, and biological catalytic systems have provided provocative ideas about the structure and properties of metal N(2)O adducts and derived intermediates. These ideas are likely to inform efforts to design more effective catalysts for N(2)O remediation.