Methane activation by [LnO]+: The 4f orbital matters

As the “holy grail” in the field of chemistry, the catalytic activation of methane has actually been a subject of fantastic interest in the field of heterogeneous catalysis. Gas-phase experiments supply a perfect platform for checking out catalytic response systems and acquiring extensive understanding of electronic structures.

Over the previous couple of years, a great deal of compounds efficient in triggering methane in the gas stage have actually been found, and even total catalytic cycles for methane conversion have actually been developed. The system of preliminary C-H bond activation in methane can be divided into hydrogen atom transfer (HAT), proton-coupled electron transfer (PCET), and hydride transfer (HT), and the building and construction of low-energy activation websites has actually ended up being a current research study hotspot.

Just recently, the research study group led by Professor Shao-Dong Zhou reported on the response of [LnO]⁺ ions (Ln = Sm-Lu) with methane, and speculative outcomes revealed that [LnO]⁺ ions can draw out a hydrogen atom from methane, with [EuO]⁺ and [YbO]⁺ displaying the greatest reactivity.

Quantum chemical estimations exposed that [LnO]⁺ ions are triply bonded ions with unpaired electrons inhabiting the 4f orbitals. In the responses of [EuO]⁺/[YbO]⁺ with methane, among the Ln-O bonds goes through homolytic cleavage, forming an oxygen radical, therefore triggering methane through the HAT system.

In other systems, methane activation happens by means of the PCET system through heterolytic cleavage of Ln-O bonds. It deserves keeping in mind that upon development of the shift statethe tenancy of the 4f orbitals in [EuO]⁺/[YbO]⁺ modifications from 4f⁶/ 4f¹³ to 4f⁷/ 4f¹⁴leading to a half-filled or fully-filled state of the 4f orbitals, supporting the shift state and reducing the response barrier.

This varies from previous research studies, where the interaction in between lanthanide metals and oxygen ligands caused the degeneracy of the 4f orbitals, decreasing the response barrier instead of the 5d-4f electron shift. This paper’s speculative and computational outcomes suggest that reasonable modulation of the tenancy of the 4f orbitals might be helpful for the style of extreme responses.

The findings are released in the journal Science China Chemistry

More details:
Bowei Yuan et al, Methane activation by [LnO]+: the 4f orbital matters, Science China Chemistry (2023 ). DOI: 10.1007/ s11426-023-1801-4