CoO-metalloxocubes: a new class of perovskite-like neutral clusters with cubic aromaticity.

Exploring stable clusters to understand structural evolution from atoms to macroscopic matter and to construct new materials is interesting yet challenging in chemistry. Utilizing our newly developed deep-ultraviolet laser ionization mass spectrometry technique, here we observe the reactions of neutral cobalt clusters with oxygen and find a very stable cluster species of CoO that dominates the mass distribution in the presence of a large flow rate of oxygen gas. The results of global-minimum structural search reveal a unique cubic structure and distinctive stability of the neutral CoO cluster that forms a new class of metal oxides that we named as 'metalloxocubes'. Thermodynamics and kinetics calculations illustrate the structural evolution from icosahedral Co to the metalloxocube CoO with decreased energy, enhanced stability and aromaticity. This class of neutral oxygen-passivated metal clusters may be an ideal candidate for genetic materials because of the cubic nature of the building blocks and the stability due to cubic aromaticity.