Chinese Puzzle Molecule: A 15 Hydride, 28 Copper Atom Nanoball

The syntheses of the first rhombicuboctahedral copper polyhydride complexes Cu₂₈(H)₁₅(S₂CNR)₁₂]PF₆ (NR=NⁿPr₂ or aza‐15‐crown‐5) are reported. These complexes were analyzed by single‐crystal X‐ray and one by neutron diffraction. The core of each copper hydride nanoparticle comprises one central interstitial hydride and eight outer‐triangular‐face‐capping hydrides. A further six face‐truncating hydrides form an unprecedented bridge between the inner and outer copper atom arrays. The irregular inner Cu₄ tetrahedron is encapsulated within the Cu₂₄ rhombicuboctahedral cage, which is further enclosed by an array of twelve dithiocarbamate ligands that subtends the truncated octahedron of 24 sulfur atoms, which is concentric with the Cu₂₄ rhombicuboctahedron and Cu₄ tetrahedron about the innermost hydride. For these compounds, an intriguing, albeit limited, H₂ evolution was observed at room temperature, which is accompanied by formation of the known ion Cu₈(H)(S₂CNR)₆]⁺ upon exposure of solutions to sunlight, under mild thermolytic conditions, and on reaction with weak (or strong) acids.