In the solid state, 2 crystallises in a tetragonal space group (Figure ). The core of 2 is made up of a distorted tetrahedra of magnesium sites that bridge a central m4 oxide ligand, formally derived from oxygen atom abstraction from CO. Each -diketiminate ligand is dinucleating and coordinates two adjacent Mg atoms along opposite edges of the tetrahedra. The rigid structure of the ligand is perfectly suited to align with the Mg---Mg separation of 3.256(2) Å. Of the remaining edges of the Mg4 tetrahedra one is bridged by a hydride ligand, another the C2 ligand from coupling and deoxygenation of CO, the rest remain open. The C 1 -C 2 and C 1 -O bond lengths take values of 1.29(3) and 1.353 (17) Å respectively and are consistent with the proposed formulation as an acetaldehyde enolate. The hydride and enolate sites are symmetry related, and there is positional disorder between these positions. Nevertheless, the structure is unambiguous and consistent with the solution characterization of 2.