The oxidation state in low-valent beryllium and magnesium compounds

Low-valent group 2 (E = Be and Mg) stabilized compounds have been long synthetically pursued. Here we discuss the electronic structure of a series of Lewis base-stabilized Be and Mg compounds. Despite the accepted zero(0) oxidation state nature of the group 2 elements of some recent experimentally accomplished species, the analysis of multireference wavefunctions provides compelling evidence for a strong diradical character with an oxidation state of +2. Thus, we elaborate on the distinction between a description as a donor-acceptor interaction L(0) ⇆ E(0) reversible arrow L(0) and the internally oxidized situation, better interpreted as a diradical L(-1) -> E(+2) <- L(-1) species. The experimentally accomplished examples rely on the strengthened bonds by increasing the pi-acidity of the ligand; avoiding this interaction could lead to an unprecedented low-oxidation state.

Automated summary

This article discusses the electronic structure of Lewis base-stabilized Be and Mg compounds and provides an explanation for their proposed oxidation states. The experimentally accomplished compounds rely on increasing the π-acidity of the ligand to strengthen the chemical bonds, and it is suggested that avoiding this interaction could lead to the presence of low-oxidation states.