Zeroing in on magnesium

Like most of the elements in the periodic table’s second column, magnesium eagerly gives away a couple of electrons to achieve a full outer shell and a +2 oxidation state. For the first time, chemists have maneuvered magnesium into a stable complex (shown) where it possesses all its electrons (Nature 2021, DOI: 10.1038/s41586-021-03401-w). Sjoerd Harder and colleagues at Friedrich Alexander University Erlangen-Nuremberg accomplished this feat with the help of bulky β-diketiminate ligands. To make the Mg(0) complex, the chemists reduced ligand-bound Mg²⁺ with fine sodium metal. As a result, the complex contains the first observed Mg–Na bonds. Although the complex is moderately stable at room temperature, it is highly reactive, readily reducing Na ions to Na metal and breaking H₂ as well as a C–F bond. When dissolved in benzene, the Mg(0) complex slowly decomposes to form a structure with a linear Mg₃ core. The researchers suggest that such Mg metal clusters might be fleeting intermediates in the formation of Grignard reagents, which have been synthetic tools for more than a century even though their formation remains something of a mystery.