Zintl phases contain polyanions, such as [P₇]^3–. There is some research involving catalytic uses of Zintl-derived clusters, and clusters based on a [P₇] framework have shown some interesting reactivities. John E. McGrady, University of Oxford, UK, Meera Mehta, University of Manchester, UK, and colleagues have found that [P₇]-derived clusters can be used as catalysts for the hydroboration of carbonyl compounds

The team synthesized the boron-functionalized heptaphosphide Zintl cluster [(BBN)P₇]^2– from a [P₇]^3– salt, which was first converted to a [HP₇]^2– salt. The [HP₇]^2– salt was reacted with the 9-borabicyclo[3.3.1]nonane dimer (HBBN)₂ in tetrahydrofuran (THF) under elimination of H₂ to give the desired boron-functionalized heptaphosphide. According to the researchers, this dehydrocoupling approach is an unprecedented reaction pathway for the functionalization of Zintl clusters.

The sodium salt [Na(18-Crown-6)]₂[(BBN)P₇] was then used as a catalyst in the hydroboration of aldehydes, ketones, carbodiimides, isocyanates, and CO₂. Reductions of carbonyls are widely used, e.g., in the chemical industry, and the reduction of CO₂ to give useful products is important for sustainable chemistry. The team found that the cluster can promote these reactions under mild conditions and serve as a transition-metal-free catalyst. CO₂, for example, was selectively and efficiently reduced to methoxyborane.

• A Zintl Cluster for Transition Metal-Free Catalysis: C=O Bond Reductions,
  Bono van IJzendoorn, Saad F. Albawardi, Inigo J. Vitorica-Yrezabal, George F. S. Whitehead, John E. McGrady, Meera Mehta,
  J. Am. Chem. Soc. 2022.
  https://doi.org/10.1021/jacs.2c08559