Bulking Up Water Oxidation: Storing solar energy by water oxidation, in a process akin to photosynthesis, is a promising approach for building a renewable energy infrastructure. Unfortunately, many of the most active synthetic catalysts for this process fall prey to degradation by the generated oxygen. Yin et al. (p. 342 , published online 11 March; see the Perspective by Hurst ) used bulky polyoxometalate ligands to protect a catalytic cobalt center from this fate. The full complex was easily prepared by mixing proper ratios of inexpensive tungsten, cobalt, and phosphate salts in boiling water. After isolating and redissolving the catalyst in slightly basic aqueous solution, rapid oxygen generation was observed with a ruthenium-based oxidant.

Aromaticity is a concept invented to account for the unusual stability of an important class of organic molecules: the aromatic compounds. Here we report experimental and theoretical evidence of aromaticity in all-metal systems. A series of bimetallic clusters with chemical composition MAl ₄ ^– (M = Li, Na, or Cu), was created and studied with photoelectron spectroscopy and ab initio calculations. All the MAl ₄ ^– species possess a pyramidal structure containing an M ⁺ cation interacting with a square Al ₄ ^2– unit. Ab initio studies indicate that Al ₄ ^2– exhibits characteristics of aromaticity with two delocalized π electrons (thus following the 4 n + 2 electron counting rule) and a square planar structure and maintains its structural and electronic features in all the MAl ₄ ^– complexes. These findings expand the aromaticity concept into the arena of all-metal species.

We report the experimental and theoretical characterization of antiaromaticity in an all-metal system, Li ₃ Al ₄ ^– , which we produced by laser vaporization and studied with the use of photoelectron spectroscopy and ab initio calculations. The most stable structure of Li ₃ Al ₄ ^– found theoretically contained a rectangular Al ₄ ^4– tetraanion stabilized by the three Li ⁺ ions in a capped octahedral arrangement. Molecular orbital analyses reveal that the rectangular Al ₄ ^4– tetraanion has four π electrons, consistent with the 4 n Hückel rule for antiaromaticity.